{"id":66460,"date":"2026-10-06T17:17:37","date_gmt":"2026-10-06T14:17:37","guid":{"rendered":"https:\/\/wpcalc.com\/en\/?p=66460"},"modified":"2026-10-06T17:17:37","modified_gmt":"2026-10-06T14:17:37","slug":"empirical-formula-calculator","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/chemistry\/empirical-formula-calculator\/","title":{"rendered":"Empirical Formula Calculator"},"content":{"rendered":"<section class=\"not-prose calculator-box\" aria-labelledby=\"calculator-title\"><div class=\"flex items-baseline sm:items-center justify-between gap-2 sm:gap-3\"><div class=\"flex flex-col sm:flex-row sm:items-center gap-2\"><span class=\"icon icon-calculator text-primary-700! text-base! dark:text-primary-300!\" aria-hidden=\"true\"><\/span><h2 id=\"calculator-title\" class=\"text-lg font-display font-bold\">Find a Compound&#039;s Empirical Formula from Its Composition<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"66460\" data-favorite-title=\"Empirical Formula\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/chemistry\/empirical-formula-calculator\/\" data-favorite-excerpt=\"Enter the mass percentages or gram amounts of each element in a compound and instantly get its empirical formula, mole ratios, and the molar mass of the simplest formula.\" aria-label=\"Add to Favorites\" data-favorite-icon=\"icon icon-chemistry\">\n    <span class=\"icon icon-shape-star-empty\" aria-hidden=\"true\"><\/span>\n  <\/button>\n  <div class=\"calcdash-favorite__tip\" aria-hidden=\"true\">\n   <span class=\"favorite-tooltip\" id=\"favorite-tooltip\"><\/span>\n  <\/div>\n  <span class=\"sr-only\" role=\"status\" id=\"favorite-status\"><\/span>\n<\/div><\/div><form action=\"https:\/\/wpcalc.com\/en\/chemistry\/empirical-formula-calculator\/\" method=\"POST\" class=\"calculator\" id=\"calculator-66460\" data-post=\"66460\"><fieldset class=\"fieldset-input is-1\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field\" id=\"input-1\"><label for=\"field-1\">Elements and Their Masses or Mass Percentages<\/label><textarea id=\"field-1\" name=\"elements_and_their_masses_or_mass_percentages\">C 40.0; H 6.7; O 53.3<\/textarea><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"66460\">Calculate<\/button><button type=\"reset\">Reset<\/button><\/div><div class=\"field is-checkbox hidden!\" id=\"field-auto-calc\"><input type=\"checkbox\" id=\"auto-calc\"><label for=\"auto-calc\">Calculate automatically<\/label><small>If enabled, the result will update automatically when you change any value.<\/small><\/div><div class=\"fieldset-result is-hidden\" aria-labelledby=\"result-title\" aria-live=\"polite\" role=\"region\"> <h3 class=\"result-title bg-gradient-to-r from-primary-50 to-gray-50 dark:from-primary-900 dark:to-gray-800\" id=\"result-title\"><span class=\"icon icon-s-pulse\" aria-hidden=\"true\"><\/span> Empirical Formula Results<\/h3><div class=\"result-box\"><div class=\"field-result is-column\" id=\"output-1\"><span class=\"field-title\"><span>Empirical Formula (Simplest Whole-Number Formula)<\/span><\/span><span class=\"field-value\" id=\"result-1\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><div class=\"field-result is-column\" id=\"output-2\"><span class=\"field-title\"><span>Element Mole Ratios<\/span><\/span><span class=\"field-value\" id=\"result-2\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><div class=\"field-result\" id=\"output-3\"><span class=\"field-title\"><span>Empirical Formula Molar Mass<\/span><\/span><span class=\"field-value\" id=\"result-3\" data-unit=\"g\/mol\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><\/div><div class=\"result-actions\"><button type=\"button\" class=\"copy-link\"><svg viewBox=\"0 0 20 20\" fill=\"currentColor\" aria-hidden=\"true\"><path d=\"M12.232 4.232a2.5 2.5 0 0 1 3.536 3.536l-1.225 1.224a.75.75 0 0 0 1.061 1.06l1.224-1.224a4 4 0 0 0-5.656-5.656l-3 3a4 4 0 0 0 .225 5.865.75.75 0 0 0 .977-1.138 2.5 2.5 0 0 1-.142-3.667l3-3Z\"\/><path d=\"M11.603 7.963a.75.75 0 0 0-.977 1.138 2.5 2.5 0 0 1 .142 3.667l-3 3a2.5 2.5 0 0 1-3.536-3.536l1.225-1.224a.75.75 0 0 0-1.061-1.06l-1.224 1.224a4 4 0 1 0 5.656 5.656l3-3a4 4 0 0 0-.225-5.865Z\"\/><\/svg><span class=\"copy-link__text\">Copy link to this calculation<\/span><\/button><span class=\"sr-only\" role=\"status\" id=\"copy-link-status\"><\/span><\/div><\/div><a href=\"#respond\" class=\"hidden transition-opacity duration-300 opacity-0 w-50 text-sm justify-center items-center gap-2 px-4 py-2 rounded bg-gray-200 text-gray-700 hover:bg-gray-300\" id=\"leave-comment\"><span class=\"icon icon-comments\" aria-hidden=\"true\"><\/span>Leave a Comment<\/a><\/form><\/section><section id=\"calc-reactions\" class=\"not-prose hidden my-12 bg-gradient-to-r from-primary-50 to-gray-50 border border-indigo-100 rounded-xl px-6 py-4 shadow-sm\" data-post=\"66460\" aria-live=\"polite\" aria-labelledby=\"calc-reactions-title\"><p id=\"calc-reactions-title\" class=\"text-sm text-gray-500 text-center mb-2\">How did this result make you feel?<\/p><div role=\"group\" aria-labelledby=\"calc-reactions-title\" class=\"grid grid-cols-3 sm:flex sm:flex-row sm:justify-around gap-4 sm:items-center sm:flex-wrap\"><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"like\"><span class=\"reaction-count\" data-reaction-count=\"like\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude00 <\/span><span class=\"reaction-description font-medium\">Like <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"helpful\"><span class=\"reaction-count\" data-reaction-count=\"helpful\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\udca1 <\/span><span class=\"reaction-description font-medium\">Helpful <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"confused\"><span class=\"reaction-count\" data-reaction-count=\"confused\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude15 <\/span><span class=\"reaction-description font-medium\">Confused <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"disappointed\"><span class=\"reaction-count\" data-reaction-count=\"disappointed\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude1e <\/span><span class=\"reaction-description font-medium\">Disappointed <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"inaccurate\"><span class=\"reaction-count\" data-reaction-count=\"inaccurate\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\u274c <\/span><span class=\"reaction-description font-medium\">Inaccurate <\/span><\/button><\/div><div id=\"reaction-message\" class=\"hidden mt-8 rounded-md border border-primary-100 bg-white\/50 backdrop-blur-sm px-4 py-2 text-sm text-center shadow-sm\"><\/div><\/section><div class=\"calcdash-ad not-prose calcdash-ad--calc_result calcdash-ad--in-article\"><ins class=\"adsbygoogle\" style=\"display:block\" data-ad-client=\"ca-pub-1721569815777345\" data-ad-slot=\"6317458308\" data-ad-layout=\"in-article\" data-ad-format=\"fluid\"><\/ins><script>(adsbygoogle = window.adsbygoogle || []).push({});<\/script><\/div>\n<style id=\"wpcoderpro-inline-1\">.formula-box {\r\n\tborder-bottom: none !important;\r\n}<\/style><section class=\"formula-box\" aria-labelledby=\"formula-title\">\r\n\t<div id=\"formula-title\" class=\"not-prose font-display mb-4\"><span class=\"icon icon-formula\" aria-hidden=\"true\"><\/span><h2>Empirical Formula<\/h2><\/div>\r\n\t<figure class=\"not-prose formula\">\r\n\t\t<figcaption class=\"formula-title\">Formula<\/figcaption>\r\n\t\t<div class=\"text-base text-gray-800\" id=\"formula\">\n\\[ n_i = \\frac{m_i}{A_i}, \\qquad r_i = \\frac{n_i}{n_{\\min}}, \\qquad \\text{subscript}_i = r_i \\times k \\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(m_i\\) \u2014 mass (or mass percent) of element \\(i\\)<\/li>\n<li>\\(A_i\\) \u2014 atomic weight of element \\(i\\) (g\/mol)<\/li>\n<li>\\(n_i\\) \u2014 moles of element \\(i\\)<\/li>\n<li>\\(n_{\\min}\\) \u2014 the smallest number of moles among all elements<\/li>\n<li>\\(r_i\\) \u2014 the mole ratio of element \\(i\\) relative to the least abundant element<\/li>\n<li>\\(k\\) \u2014 the smallest whole number that turns every ratio into an integer<\/li>\n<\/ul>\n<p>Each mass is converted to moles by dividing by the element's atomic weight. Dividing every mole count by the smallest one gives relative ratios, which are then scaled by the smallest whole-number multiplier \\(k\\) (1, 2, 3\u2026) that makes all subscripts integers. The result is the simplest whole-number formula of the compound.<\/p>\n<p>\r\n<\/section>\n<style id=\"wpcoderpro-inline-459\">.calculation-box {\r\n\tborder-bottom: none !important;\r\n}<\/style><section id=\"calculation\" class=\"calculation-box\" aria-labelledby=\"calculation-title\">\r\n\t<div id=\"calculation-title\" class=\"not-prose font-display\"><span class=\"icon icon-unordered-list\" aria-hidden=\"true\"><\/span><h2>Empirical Formula \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> a compound is analyzed and found to contain 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass.<\/p>\n<p>Convert each mass percent to moles:<\/p>\n<p>\\[ n_C = \\frac{40.0}{12.011} = 3.330 \\text{ mol}, \\quad n_H = \\frac{6.7}{1.008} = 6.647 \\text{ mol}, \\quad n_O = \\frac{53.3}{15.999} = 3.333 \\text{ mol} \\]<\/p>\n<p>Divide each by the smallest value (3.330):<\/p>\n<p>\\[ C: 1.000, \\quad H: 1.995 \\approx 2, \\quad O: 1.001 \\approx 1 \\]<\/p>\n<p>The ratios are already whole numbers (\\(k = 1\\)), so no multiplier is needed.<\/p>\n<p><strong>Result:<\/strong> the empirical formula is <strong>CH<sub>2<\/sub>O<\/strong>, with a molar mass of 30.026 g\/mol. (With an experimental molar mass you could go one step further and find the molecular formula \u2014 see the <a href=\"https:\/\/wpcalc.com\/en\/chemistry\/molecular-mass-using-gmv-law\/\">molecular mass calculator<\/a>.)<\/p>\n<p>\n\r\n<\/section>\n<h2>How to use the calculator<\/h2>\n<ol>\n<li>In the <strong>Elements and Their Masses or Mass Percentages<\/strong> field, list every element in the compound: its chemical symbol followed by a value, one element per entry. Separate entries with a newline, semicolon, comma, colon, or \"=\". For example: <code>C 40.0; H 6.7; O 53.3<\/code>.<\/li>\n<li>Enter each value either as a mass percent (as in combustion analysis data) or as a mass in grams (as in lab weighing data) \u2014 the two give the same result because only the ratios matter. Do not mix units within one entry list; use all percentages or all grams.<\/li>\n<li>Click <strong>Calculate<\/strong>. The tool converts each entry to moles using IUPAC atomic weights, finds the smallest whole-number ratios, and reduces them to lowest terms.<\/li>\n<li>Read the results: the <strong>Empirical Formula (Simplest Whole-Number Formula)<\/strong>, a table of <strong>Element Mole Ratios<\/strong> showing every intermediate step, and the <strong>Empirical Formula Molar Mass<\/strong> in g\/mol.<\/li>\n<\/ol>\n<h2>What is an empirical formula?<\/h2>\n<p>The empirical formula of a compound is the simplest whole-number ratio of atoms of each element it contains. It tells you the <em>proportions<\/em> of the elements, not the actual number of atoms in one molecule. Glucose, for example, has the molecular formula C<sub>6<\/sub>H<sub>12<\/sub>O<sub>6<\/sub>, but its empirical formula is CH<sub>2<\/sub>O \u2014 the same 1:2:1 ratio, reduced to lowest terms. Formaldehyde (CH<sub>2<\/sub>O), acetic acid (C<sub>2<\/sub>H<sub>4<\/sub>O<sub>2<\/sub>), and glucose all share this empirical formula, which is why the empirical formula alone cannot identify a unique substance.<\/p>\n<p>Empirical formulas come directly from experimental composition data. In combustion analysis, an instrument measures the masses of CO<sub>2<\/sub> and H<sub>2<\/sub>O produced from a sample, and these are converted back to masses of carbon and hydrogen. In gravimetric analysis, an element may be precipitated and weighed directly. Whatever the method, the raw output is a set of masses or mass percentages \u2014 exactly what this calculator takes as input.<\/p>\n<p>To interpret the results, focus on the mole ratio table. The \"\u00f7 smallest\" column shows the relative ratios before rounding; values very close to whole numbers (like 1.995 \u2248 2) confirm clean data, while awkward ratios such as 1.33 (4\/3) or 2.50 (5\/2) signal that the raw ratios must be multiplied by 3 or 2 respectively to reach whole numbers. The calculator performs this scaling automatically for multipliers up to 12.<\/p>\n<p>Once you know the empirical formula, comparing its molar mass with the experimentally measured molar mass of the compound gives the molecular formula: the multiplier \\(n = M_{\\text{compound}} \/ M_{\\text{empirical}}\\) scales every subscript. If the two masses are equal, the empirical and molecular formulas are the same.<\/p>\n<h2>Tips, assumptions, and limitations<\/h2>\n<ul>\n<li><strong>Percentages or grams both work.<\/strong> If your percentages do not sum to exactly 100% (common with experimental error or missing oxygen by difference), the calculator still works \u2014 ratios, not totals, determine the formula.<\/li>\n<li><strong>Oxygen by difference.<\/strong> Many analyses report C and H directly and obtain oxygen as 100% minus the rest. You can enter that remainder as a normal entry, e.g. <code>C 40.0; H 6.7; O 53.3<\/code>.<\/li>\n<li><strong>Experimental error is tolerated.<\/strong> Ratios within about 2% of a whole number are rounded to it. If the data cannot fit any whole-number ratio with multipliers up to 12, the calculator reports the ratios rounded to two decimals instead \u2014 a sign the input data should be double-checked.<\/li>\n<li><strong>Supported elements.<\/strong> The calculator recognizes the standard one- and two-letter symbols of the common elements (about 60 of them, from hydrogen to uranium). Two-letter symbols are case-corrected automatically, so \"cl\" is read as chlorine Cl, not C + l.<\/li>\n<li><strong>Duplicate entries are combined.<\/strong> If the same element appears more than once, the values are added together before the ratio is computed.<\/li>\n<li><strong>The result is empirical, not molecular.<\/strong> To get the molecular formula you also need the molar mass of the compound; for that step, see the <a href=\"https:\/\/wpcalc.com\/en\/chemistry\/molecular-mass-using-gmv-law\/\">molecular mass calculator<\/a> or the <a href=\"https:\/\/wpcalc.com\/en\/chemistry\/atomic-mass\/\">atomic mass calculator<\/a> to check individual atomic weights. If you also need to convert between atoms and moles while working out compositions, the <a href=\"https:\/\/wpcalc.com\/en\/chemistry\/convert-atoms-to-moles\/\">atoms-to-moles converter<\/a> can help, and once you have both sides of a reaction you can balance it with the <a href=\"https:\/\/wpcalc.com\/en\/chemistry\/balancing-chemical-equations\/\">chemical equation balancer<\/a>.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Enter the mass percentages or gram amounts of each element in a compound and instantly get its empirical formula, mole ratios, and the molar mass of the simplest formula.<\/p>\n","protected":false},"author":3168,"featured_media":0,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[54],"tags":[56],"class_list":["post-66460","post","type-post","status-publish","format-standard","hentry","category-chemistry","tag-stoichiometry"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/66460","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/users\/3168"}],"replies":[{"embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/comments?post=66460"}],"version-history":[{"count":1,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/66460\/revisions"}],"predecessor-version":[{"id":66461,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/66460\/revisions\/66461"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=66460"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=66460"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=66460"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}