Weight / Mass Converter
Convert a mass value between grams, kilograms, pounds, ounces, tons, and other units. Enter the value, then choose the From Unit and To Unit.
Convert Weight or Mass Between All Units
Weight/Mass Conversion Formula
Where:
- \(V_{\mathrm{from}}\) — the number entered in Weight/Mass Value
- \(V_{\mathrm{to}}\) — the Converted Value
- \(F_{\mathrm{from}}\) — grams per From Unit
- \(F_{\mathrm{to}}\) — grams per To Unit
The converter first expresses the entered mass in grams, then divides by the number of grams in one target unit. Using the same reference unit for both factors makes it possible to convert directly between any two units in the menus.
Weight/Mass – Calculation Example
Example: enter 100 for Weight/Mass Value, select Gram as the From Unit, and select Kilogram as the To Unit.
One gram is 1 gram, and one kilogram is 1,000 grams, so:
\[100\times\frac{1}{1000}=0.1\]
Result: 100 grams = 0.1 kilograms.
How to use the calculator
- Enter a nonnegative number in Weight/Mass Value. Decimals are accepted.
- Choose the unit of that number from From Unit.
- Choose the unit you need from To Unit.
- Read the Converted Value in your selected To Unit. To reverse the conversion, exchange the two unit selections.
The initial settings are 100, Gram, and Kilogram, producing 0.1. The result is for one selected target unit at a time; it is not a list of conversions into every available unit.
Understanding weight and mass conversions
Mass describes how much matter an object contains. In everyday use, people also say “weight” when giving a value in grams, kilograms, or pounds. This converter follows that common usage: it converts between mass units, not between mass and a force such as newtons. An object's mass stays the same in different gravitational fields, while its weight as a force changes.
Conversion changes the unit and the numerical value, but not the quantity represented. For example, 1 kilogram and 1,000 grams describe the same mass. When converting to a smaller unit, the number usually grows; when converting to a larger unit, it usually shrinks. This distinction helps when checking a result: 100 grams should be less than 1 kilogram, so its kilogram value must be less than 1.
Some unit names need particular care. A US hundredweight is 100 pounds, while a UK hundredweight is 112 pounds. A US short ton is 2,000 pounds, and a UK long ton is 2,240 pounds. A metric ton, also called a tonne, is 1,000 kilograms. Choosing the correct regional definition matters much more than adding extra decimal places to a result.
Selected unit factors
These are the grams-per-unit factors used in the conversion formula. They can help you check a calculation or distinguish similarly named units.
| Unit | Grams per unit |
|---|---|
| Grain | 0.06479891 |
| Dram | 1.7718451953125 |
| Ounce | 28.349523125 |
| Pound | 453.59237 |
| Kilogram | 1,000 |
| Hundredweight (US) | 45,359.237 |
| Hundredweight (UK) | 50,802.34544 |
| Short Ton | 907,184.74 |
| Long Ton | 1,016,046.9088 |
| Metric Ton | 1,000,000 |
Assumptions and practical tips
The calculator accepts zero and positive values. It rounds the displayed Converted Value to six decimal places. If you convert a tiny quantity into a much larger unit, the displayed result may therefore be zero even though the unrounded quantity is not. For very small masses, choosing micrograms or milligrams as the To Unit can make the result easier to read.
The menus include several names for identical factors: Pound and Pound (lb) both use 453.59237 grams; Long Ton and Ton (UK) match; Short Ton and Ton (US) match; and Metric Ton, Ton (Metric), Tonne, and Megagram each equal 1,000,000 grams. These labels do not indicate different conversion rates. Stone is not an available unit.
For metric units beyond those shown here, the Metric Prefix calculator can help clarify powers of ten. If you know a volume of water and need to estimate its mass instead, use the Water Weight calculator; a unit conversion alone cannot determine mass from volume.
Frequently Asked Questions
How do I convert pounds to kilograms by hand?
Multiply the number of pounds by 0.45359237. For example, 150 pounds is about 68.04 kilograms. For a quick estimate, divide pounds by 2.2 instead; it is less precise but usually close enough for everyday comparisons.
How do I convert a weight written in pounds and ounces?
Convert it to a single unit first: multiply the pounds by 16, then add the ounces. For example, 5 pounds 8 ounces is 88 ounces, or 5.5 pounds. Enter that total using the matching From Unit. Be careful not to enter 5.8 pounds: eight ounces is half a pound, not eight-tenths.
Are ounces of weight the same as fluid ounces?
No. An ounce of weight measures mass, while a fluid ounce measures volume. You cannot convert between them without knowing the substance’s density. For example, eight fluid ounces of water and eight fluid ounces of oil occupy the same volume but have different masses. Choose Ounce here only when your starting value is a mass.
How can I convert stone if it is not in the unit list?
Use pounds as an intermediate unit: one stone equals 14 pounds. Multiply the number of stone by 14, enter the result as pounds, and select the unit you want. For example, 10 stone is 140 pounds, or approximately 63.503 kilograms. If a measurement also includes pounds, add those pounds before converting.
What do gross, net, and tare weight mean when converting a package?
Gross weight includes the product and its packaging; tare weight is the packaging alone; net weight is the product alone. Subtract tare from gross to find net weight before entering a value if you need the product’s mass. Changing units does not remove packaging or change which of these quantities a measurement represents.
How do I convert between milligrams, micrograms, and grams?
One gram equals 1,000 milligrams or 1,000,000 micrograms, and one milligram equals 1,000 micrograms. Move the decimal three places for each step between grams, milligrams, and micrograms. For example, 0.025 grams is 25 milligrams or 25,000 micrograms. For medication doses, verify both the number and unit against the label or a professional’s instructions.
How many digits should I keep after converting a mass?
Keep only as much precision as the original measurement supports. If a scale reads to the nearest 0.1 kilogram, a converted pound value with six decimal places suggests accuracy the scale did not provide. Extra digits can help during an intermediate calculation, but round the final figure to a sensible number of significant digits.
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