Unit Converters: Temperature, Length, Mass and More

Convert measurements for everyday tasks, study, and technical work. These tools cover length, area, volume, mass, temperature, speed, pressure, energy, and electrical units. Start with Meters to Feet, Acres to Square Meters, or Fahrenheit to Celsius, Kelvin & More for common conversions.Students, engineers, cooks, and shoppers can also use specialized tools such as the Viscosity Converter, Cooking Measurement, Ring Size, Shoe Size, and Digital Storage. Choose a calculator below to compare units or sizes without working through conversion formulas by hand.

Physics units 56

Viscosity Converter

Convert between dynamic viscosity units (Pa·s, mPa·s, Poise, cP) and kinematic viscosity units (m²/s, mm²/s, Stokes, cSt). Enter a value, pick a unit, and add the density to switch between the two families.

mAh to Wh

Convert a battery's capacity from mAh (or Ah) to watt-hours by entering the charge rating and the nominal voltage. Useful for comparing batteries, estimating runtime, and checking airline lithium-battery limits.

Pressure Altitude

Enter a barometric pressure reading and a reference (sea-level) pressure to find the corresponding pressure altitude in feet, metres, and flight levels, based on the international standard atmosphere.

Electrical Resistivity

Convert electrical resistivity between Ω·m, Ω·cm, μΩ·cm, Ω·mm²/m, and statΩ·cm. Enter a resistivity value, then select the units to convert from and to.

Henry’s Law

Convert a Henry’s law constant between mol/(L·atm), atm·L/mol, mol/(m³·Pa), mole-fraction forms, atm·m³/mol and cm³/cm³. Enter the value, pick the From and To units, and add a temperature when cm³/cm³ is involved.

Calorific Value

Convert a calorific value between MJ/kg, kcal/kg, BTU/lb, and kJ/kg by entering a value and choosing the source and target units. Note: the calculator currently reverses conversions between different units.

Sound

Convert sound pressure levels between dB SPL, Pa, and µPa, or sound intensity between dB IL and W/m². Enter a Sound value and choose the From unit and To unit.

Beaufort Wind Scale

Convert any wind speed (m/s, km/h, mph or knots) to its Beaufort force number and description, or enter a force from 0 to 12 to see the matching speed range.

Pressure

Convert a pressure value between Pa, kPa, MPa, bar, atm, mmHg, cmHg, inHg, psi, and torr. Enter the value and select the starting and target units.

Air Density

Calculate the density of air in kg/m³, lb/ft³ and other units from temperature, pressure and relative humidity. Enter the values and get partial pressures, molar mass and virtual temperature too.

Power Units

Convert power values between watts, kilowatts, megawatts, milliwatts, horsepower (hp and PS), BTU per hour, foot-pounds per second, and kilocalories per hour. Enter a value, pick the units, and get an instant result.

Insulation R-Value

Convert insulation R-values between US imperial units (ft²·°F·h/BTU) and SI metric units (m²·K/W), and get the corresponding U-values in both systems. Just pick the unit system and enter the R-value.

Luminous Intensity

Convert luminous intensity between candela, millicandela, spherical candela, Hefner candle, and Violle. Enter a value and select the units to convert from and to.

Magnetic Flux Density

Convert magnetic flux density between tesla, millitesla, microtesla, nanotesla, gauss, and kilogauss. Enter a value, then choose the From unit and To unit.

Radiation Absorbed Dose

Convert an absorbed radiation dose between grays, milligrays, micrograys, rads, and millirads. Enter a value and choose the units to convert from and to.

Thermal Expansion

Convert a coefficient of linear thermal expansion between 1/°C, 1/K, µm/m·°C, and in/in·°F. Enter a value and select the From unit and To unit. Note: the current calculator gives incorrect results for some unit pairs.

Electric Field

Convert electric field strength between V/m, kV/m, N/C, V/cm, and statV/cm. Enter a value, then choose the From unit and To unit.

Heat Transfer

Convert a heat transfer rate between watts, kilowatts, megawatts, calories per second, and BTU-based units. Enter a rate, then select the From unit and To unit.

Inductance

Convert inductance between henries, millihenries, microhenries, nanohenries, abhenries, and stathenries. Enter a value, then choose the units to convert from and to.

Permeability

Convert a magnetic permeability value between H/m, N/A², G·cm/Oe, and μ₀ using the calculator’s stated factors. Enter a value, then choose the From unit and To unit; see the notes below before using the μ₀ or G·cm/Oe results.

Wind Chill

Enter the air temperature and wind speed to find the wind chill temperature — how cold it really feels on exposed skin — plus a frostbite risk estimate. Supports °C/°F and km/h, mph or m/s.

Electrical Capacitance

Convert capacitance between farads, millifarads, microfarads, nanofarads, picofarads, statfarads, and abfarads. Enter a value, then select the From unit and To unit.

Resistance Units

Convert electrical resistance between milliohms (mΩ), ohms (Ω), kilohms (kΩ), megohms (MΩ) and gigohms (GΩ). Enter a value, pick the source and target units, and get an instant, step-by-step conversion.

Angular Velocity

Convert angular velocity between RPM, rad/s, deg/s, rad/min and more. Enter a value in any unit and instantly get the equivalent in all other common angular speed units.

Conductance Units

Convert electrical conductance between siemens, millisiemens, microsiemens, and nanosiemens. Enter a value, then choose the From unit and To unit.

Frequency

Convert a frequency between Hz, kHz, MHz, GHz, THz, rpm, rad/s, and deg/s. Enter a Frequency value, then choose the From unit and To unit.

Mass Flow Rate

Convert a mass flow rate between kg/s, g/s, kg/min, kg/h, lb/s, lb/min, lb/h, and metric tons per hour. Enter a value and choose the units to convert from and to.

Dew Point

Enter the air temperature and relative humidity to find the dew point — the temperature at which moisture starts to condense. Results include dew point in °C, °F and K, vapour pressures and a condensation risk assessment.

Heat Index

Enter air temperature (°F or °C) and relative humidity to find the heat index — how hot it actually feels — with the matching NWS heat risk level.

Magnetic Flux

Convert magnetic flux between webers, milliwebers, microwebers, nanowebers, and maxwells. Enter a value, then choose the From unit and To unit.

Magnetomotive Force

Convert magnetomotive force between ampere-turns, kiloampere-turns, milliampere-turns, and gilberts. Enter an MMF value, then choose the units to convert from and to.

Radiation Exposure

Convert radiation exposure between C/kg, mC/kg, μC/kg, and roentgens (R). Enter an exposure value, then select the units to convert from and to.

Radioactivity

Convert radioactive activity between Bq, kBq, MBq, GBq, Ci, mCi, and µCi. Enter an activity value, then choose the starting and target units.

Light Luminance

Convert luminance between cd/m², nits, foot-lamberts, stilbs, and other units. Enter a luminance value, then choose the From unit and To unit.

Lumens to Watts

Estimate a light source’s power consumption from its brightness in lumens. Enter the luminous flux and select a luminous efficacy to convert lumens to watts.

Electric Charge

Convert electric charge between coulombs, millicoulombs, microcoulombs, nanocoulombs, and ampere-hours. Enter a value, then select the From unit and To unit.

Electric Current

Convert electric field strength between V/m, kV/m, N/C, V/cm, and statV/cm. Enter an electric field value, then select the units to convert from and to.

Moment of Inertia

Convert a moment of inertia between kg·m², g·cm², lb·ft², lb·in², and oz·in². Enter a value, then choose the From unit and To unit.

Linear Acceleration

Convert linear acceleration between m/s², cm/s², ft/s², in/s², Gal, and standard gravity (g). Enter a value, then choose the units to convert from and to.

Surface Tension

Convert surface tension between N/m, dyne/cm, mN/m, and kg/s². Enter a value, then choose the units to convert from and to.

Torque

Convert torque between N·m, kN·m, N·cm, kgf·m, lbf·ft, and lbf·in. Enter a torque value, then choose the units to convert from and to.

Molar Flow Rate

Convert a molar flow rate between mol/s, mmol/s, mol/min, mol/h, kmol/h, and mol/day. Enter a value, then select the starting and target units.

Specific Heat

Convert specific heat capacity between J/g·°C, J/kg·K, kJ/kg·K, cal/g·°C, and BTU/lb·°F. Enter a value and choose the From unit and To unit.

Acceleration Units

Convert an acceleration value between m/s², ft/s², standard gravity (g), and Gal. Enter the value, then choose the From unit and To unit.

Density Converter

Convert density values between kg/m³, g/cm³, g/mL, lb/ft³, lb/in³ and more. Enter a value, pick a unit, and get the equivalent density in all common units at once.

Thermal Conductivity

Convert thermal conductivity between W/m·K, kW/m·K, W/cm·K, cal/s·cm·K, and BTU-based units. Enter a value, then choose the From unit and To unit.

Energy

Convert an energy value between joules, calories, kilowatt-hours, BTUs, and other units. Enter a value, then choose the From unit and To unit.

Mass Flux Density

Convert mass flux density between kg/m²·s, g/cm²·s, kg/m²·h, lb/ft²·s, and lb/ft²·h. Enter a value, then choose the units to convert from and to.

Note Frequency

Convert any musical note (C0–B9) to its frequency in Hz, or find the nearest note for any frequency, including the detune in cents. Uses equal temperament with an adjustable A4 reference pitch.

Force

Convert a force between newtons, kilonewtons, dynes, pound-force, kilogram-force, ounce-force, gram-force, and kips. Enter a Force value and choose the From unit and To unit.

Surface Charge Density

Convert surface charge density between C/m², µC/m², nC/m², pC/m², and esu/cm². Enter a nonnegative value and select the starting and target units.

Electric Static Potential

Convert electric potential between volts, kilovolts, millivolts, microvolts, and statvolts. Enter a nonnegative value, then choose the units to convert from and to.

Heat Flux Density

Convert heat flux density between W/m², kW/m², cal/s·cm², BTU/h·ft², and BTU/s·ft². Enter a value, then choose the starting and target units.

Light Illumination

Convert light levels between lux, foot-candles, phot, and lumen-based units. Enter an Illumination value, then choose the From unit and To unit.

Linear Current Density

Convert linear current density between A/m, kA/m, A/cm, mA/mm, and µA/µm. Enter a value and select its original and target units.

Surface Current Density

Convert surface current density between A/m, kA/m, mA/m, A/cm, and the listed electrostatic CGS unit. Enter a value and select the units to convert from and to.

Chemistry units 21

mg to mL

Convert milligrams to milliliters (or the reverse) for liquid medicines and pure substances. Enter the concentration from the label or use a preset density, and get an instant, step-by-step result.

Blood Sugar Converter

Convert blood glucose readings between mg/dL and mmol/L instantly, and see how your fasting value compares to normal, prediabetes and diabetes reference ranges.

Gas PPM to mg/m³

Convert gas concentrations between ppm (volume) and mg/m³ (mass) using the ideal gas law. Enter the concentration, the gas molar mass, temperature and pressure to get instant results in mg/m³, ppm and µg/m³.

Brix to SG

Convert a refractometer or hydrometer reading between Brix, Plato and specific gravity. Enter your measured value, pick the unit, set the wort correction factor if needed, and get SG, °Bx, °P and estimated alcohol potential.

Cholesterol Converter

Convert cholesterol values between mg/dL and mmol/L for total cholesterol, LDL, HDL, and triglycerides. Enter your lab reading and instantly see the converted value with its interpretation category.

EC to TDS

Convert an electrical conductivity (EC) reading in µS/cm, mS/cm or S/m into an estimated TDS value in ppm. Choose the conversion factor your meter uses (0.5, 0.64 or 0.7) and get an instant result.

Fahrenheit to Celsius, Kelvin & More

Enter a temperature in Fahrenheit to see its equivalent in Celsius, Kelvin, Rankine, Newton, Delisle, Réaumur, and Rømer.

Creatinine Units

Convert a serum creatinine value between mg/dL and µmol/L instantly, and see how your result compares with typical reference ranges for men and women.

Cortisol Units

Convert a serum cortisol result between µg/dL and nmol/L instantly. Enter your lab value, pick the unit and sampling time, and see the equivalent result with typical reference ranges.

PPM Converter

Convert a concentration between ppm, percent, per mille, ppb and mg/L. Enter a value, pick its unit and the solution density to see all equivalent units at once.

Bilirubin Units

Convert a serum bilirubin result between mg/dL and µmol/L instantly, and see how your value compares with typical adult reference ranges for total and direct bilirubin.

Entropy Conversions

Convert an entropy value between the units offered by the calculator. Enter a Value, then choose the From unit and To unit; check the notes before comparing molar with total entropy or using the BTU and eV results.

Molar Concentration

Convert molar concentration between mol/L, mmol/L, kmol/m³, and other supported units. Enter a value, then choose the starting and target units.

Rankine to Celsius, Fahrenheit & more

Enter a temperature in degrees Rankine to convert it to Celsius, Fahrenheit, Kelvin, Newton, Delisle, Réaumur, and Rømer.

Vitamin D Units

Convert your 25-hydroxyvitamin D blood test result between ng/mL and nmol/L instantly. Enter your value and unit to get both measurements plus a plain-language interpretation.

Celsius to Fahrenheit, Kelvin & More

Enter a temperature in Celsius to convert it to Fahrenheit, Kelvin, Rankine, Newton, Delisle, Réaumur, and Rømer.

Reaumur to Celsius, Fahrenheit & More

Enter a temperature in degrees Reaumur to convert it to Celsius, Fahrenheit, Kelvin, Rankine, Newton, Delisle, and Rømer.

Delisle to Celsius, Fahrenheit, Kelvin & More

Enter a temperature in degrees Delisle to convert it to Celsius, Fahrenheit, Kelvin, Rankine, Newton, Réaumur, and Rømer.

Kelvin to Celsius, Fahrenheit & More

Enter a temperature in kelvin to convert it to Celsius, Fahrenheit, Rankine, Newton, Delisle, Réaumur, and Rømer.

Testosterone Units

Convert testosterone levels between ng/dL and nmol/L instantly. Enter your lab result, pick the unit, and see the equivalent value compared with typical male and female reference ranges.

Moles and Grams

Convert a substance’s mass in grams to moles. Enter the Mass of substance and its Molar mass to calculate the Amount of substance.

Other units 19

Download Time Estimator

Enter a file size in KB, MB, or GB to estimate its download time at four preset connection speeds, from 56 kbps to 100 Mbps.

Clothing Size

Convert clothing sizes between US, UK, EU and international letter sizes (XS–XXL) for women's and men's tops, dresses, skirts and pants. Enter your size, pick the system and garment type, and get all equivalents plus the key body measurement in inches and centimeters.

Knitted Fabric GSM

Enter courses per inch, stitch length in centimeters, and yarn tex to calculate the value returned by this knitted fabric GSM formula. Check the limitations before treating it as a measured fabric weight.

Gold Purity

Convert gold karats to purity percentage, fineness and hallmark stamp — or enter a percentage or fineness value to get the karat equivalent. Just pick your input type and enter the number.

Image DPI & Pixel

Find an image’s print width and height from its pixel dimensions and chosen resolution. Enter the width and height in pixels, set the DPI, and select inches or centimeters.

Alcohol Proof

Convert between alcohol by volume (ABV), US proof and UK proof instantly. Enter any strength value and see all three equivalent units plus a context for how strong that drink is.

Astronomical Distance

Convert a value between astronomical units, light-years, parsecs, kilometers, and miles. Enter a distance, then choose the From unit and To unit. Note that this calculator currently gives incorrect results for some light-year and parsec conversions.

Metric Prefix

Convert a value between metric prefixes, from nano to tera. Enter the value, then choose its current prefix and the prefix you want to convert to.

HbA1c

Convert HbA1c between percent (DCCT) and mmol/mol (IFCC) units, and see the estimated average glucose (eAG) it represents. Enter your lab result and choose its unit.

Brewing ABV

Estimate the alcohol content of your homebrew from two hydrometer readings. Enter the original gravity (OG) and final gravity (FG) to get ABV, apparent attenuation and alcohol by weight.

Aspect Ratio

Enter the width and height of an image, screen or video to find its aspect ratio, its common name (like 16:9), and the matching dimension for any proportional resize.

Data Transfer Rate

Convert data transfer rates between bits and bytes per second instantly. Enter a value in Mbps, kbps, Gbps, MB/s or any other unit and see all equivalents at once.

Digital Storage

Convert a value between bits, bytes, KB, MB, GB, and TB using 1024-based storage units. Enter an amount, then select the From unit and To unit.

CSS Units

Convert a CSS length between px, rem, em, vw, vh, pt and percent. Enter the value, pick its unit, set the root and parent font sizes plus viewport dimensions, and get all equivalents at once.

Roman Numerals

Convert any whole number from 1 to 3999 into its Roman numeral, or translate a Roman numeral back into an Arabic number. Just pick the direction, type your value, and get the result instantly.

Fuel Economy Converter

Convert fuel economy between MPG (US), MPG (UK), liters per 100 km and km/L. Enter any value, choose its unit, and get all four equivalents at once.

Ring Size

Convert between US, UK and EU ring sizes, or enter your finger circumference or a ring's inner diameter in millimetres to find your size in all systems at once.

Cooking Measurement

Convert cooking volumes between teaspoons, tablespoons, cups, US fluid ounces, milliliters, and liters. Enter a value, then choose the units to convert from and to.

Shoe Size

Convert between US men's, US women's, UK and EU shoe sizes, or enter your measured foot length in cm or inches to see your size in every system at once.

Length units 10

mm to Inches

Convert millimeters to inches and back in one step, with the exact decimal result plus the nearest fractional inch (down to 1/64 in) and the rounding error. Just type your value in either field.

Feet and Inches

Add, subtract, multiply, or divide lengths in feet and fractional inches, or convert decimal feet or centimeters. Enter your measurements and choose how precisely to display the inch fraction.

Paper Sizes

Look up the exact dimensions of any ISO A, B or C series paper size or North American size (Letter, Legal, Tabloid, ANSI) in millimetres, centimetres or inches, together with area and aspect ratio.

Yarn Count

Calculate yarn count from the number of bundles, the length of each bundle in meters, and the total yarn weight in grams. The result is meters per gram, numerically equal to metric yarn count (Nm).

Map Scale

Convert between map distance, real-world distance and map scale (representative fraction 1:N). Enter what you know — for example, a measured map distance and the scale — and get the missing value instantly.

cm to Inches

Convert centimeters to inches (or inches back to centimeters) instantly. Enter a value in either field and get the result plus feet + inches and fractional inches to the nearest 1/16.

Length Universal Converter

Convert a length or distance between meters, centimeters, millimeters, kilometers, inches, feet, yards, miles, and nautical miles. Enter a value, then choose the From unit and To unit.

Meters to Feet

Convert a length from meters to feet. Enter a nonnegative value in the Length in meters field to see the equivalent in feet.

Miles to km

Convert miles to kilometers and kilometers back to miles, plus mph to km/h and running pace (min/mi to min/km). Type a value into either field of a pair and the converter updates the rest instantly.

Linear Feet

Add up linear feet for boards, trim, moldings, fencing and decking — enter piece lengths with quantities, or convert an area in ft² to linear feet from the board width, and get total cost per linear or board foot.

Volume units 9

Cubic Feet per Minute (CFM)

Calculate airflow in cubic feet per minute (CFM) from air velocity in feet per minute (FPM) and cross-sectional area in square feet.

Volumetric Weight

Calculate a package’s volumetric weight in kilograms. Enter its length, width, and height in centimeters, then select the DIM Factor used for your shipment.

Rainfall Volume

Calculate how much water a rainfall event delivers onto any roof or surface. Enter the rainfall depth, collection area and an optional roof efficiency to get the volume in liters, US gallons and cubic meters.

Tank Volume

Calculate the total and filled volume of cylindrical, capsule, oval, rectangular and cone-bottom tanks. Enter the tank dimensions and the measured liquid depth to get the volume in liters, gallons, ft³ and m³, plus the fill percentage.

Volume Unit Universal

Convert a volume between liters, milliliters, cubic units, and US customary units. Enter a Value, then choose the From Unit and To Unit.

Cubic Yards

Calculate cubic yards for soil, gravel, mulch or concrete. Enter the area dimensions and depth, and get volume, weight, bag count and cost.

Cubic Feet

Calculate the volume in cubic feet of a box or room, cylinder, sphere, or a whole list of moving boxes. Enter dimensions in feet, inches, cm or m and get instant conversions to in³, m³, liters and gallons.

ml to oz

Convert milliliters to fluid ounces and back in one click — US customary, US nutrition-labeling or UK imperial ounces. Type a value in either field and get cups, tablespoons and teaspoons too.

Volume Table

Use this volume table to compare units such as cubic meters, liters, and gallons. Find your starting unit and the unit you want to convert to.

Basic units 9

Feet Per Minute to CFM

Convert air velocity in feet per minute to airflow in cubic feet per minute. Enter the velocity and cross-sectional area, then select the area unit.

Permille to Decimal and Meter

Convert a permille (‰) value to a decimal, or find its equivalent distance in meters over 1 km. Enter the value and choose a result under Convert to.

Water Weight

Convert a quantity of water between volume and mass units. Enter a value, then choose the From and To units to see the equivalent at an assumed density of 1 kg/L.

Weight / Mass

Convert a mass value between grams, kilograms, pounds, ounces, tons, and other units. Enter the value, then choose the From Unit and To Unit.

Grams to Ounces

Convert grams to ounces and ounces back to grams instantly. Choose avoirdupois ounces for everyday weights or troy ounces for gold and silver, and get the exact formula, a pounds-plus-ounces breakdown, and full conversion tables.

kg to lbs

Convert kilograms to pounds and pounds to kilograms using the exact 1959 definition 1 lb = 0.45359237 kg. Enter a weight in either field and also get ounces, grams, and stone.

Circle to Angle Units

Convert an angle between degrees, radians, gradians, sextants, arcminutes, and arcseconds. Enter an angle value, then select the source and target units.

Speed Converter

Convert a speed between km/h, mph, m/s, ft/s, knots and Mach instantly. Enter any value, pick the unit, and see the equivalent in all other common speed units.

Time Converter

Convert a time value between nanoseconds, milliseconds, seconds, minutes, hours, days, weeks, months and years. Enter any value, pick the source unit, and see the result in every other unit at once.

Land area units 5

Hectares to Square Kilometers

Convert an area from hectares to square kilometers. Enter a nonnegative value in the Hectares field to see the result in km².

Land Area Unit

Convert land area between square meters, square feet, acres, hectares, and six other units. Enter an area, then choose the units to convert from and to.

Acres to Square Meters

Convert land area from acres to square meters. Enter a nonnegative value in the Acres field to see the result in m².

Square Feet to Acres

Convert an area from square feet to acres. Enter the area in the Square Feet field to see the equivalent in acres, rounded to six decimal places.

Acreage

Calculate lot or field area in acres from a rectangle, three-sided triangle, circle, or irregular quadrilateral. Enter the dimensions and units; add a price per acre for an optional value estimate.