{"id":67423,"date":"2026-10-21T10:27:01","date_gmt":"2026-10-21T07:27:01","guid":{"rendered":"https:\/\/wpcalc.com\/en\/?p=67423"},"modified":"2026-10-21T10:27:01","modified_gmt":"2026-10-21T07:27:01","slug":"lean-body-mass-calculator","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/beauty\/lean-body-mass-calculator\/","title":{"rendered":"Lean Body Mass 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\">Estimate Your Lean Body Mass from Weight and Height<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"67423\" data-favorite-title=\"Lean Body Mass\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/beauty\/lean-body-mass-calculator\/\" data-favorite-excerpt=\"Estimate your lean body mass (LBM) from weight, height and sex using the Boer, James, Hume and Peters formulas, or get an exact value from your body fat percentage.\" aria-label=\"Add to Favorites\" data-favorite-icon=\"icon icon-appearance\">\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\/beauty\/lean-body-mass-calculator\/\" method=\"POST\" class=\"calculator\" id=\"calculator-67423\" data-post=\"67423\"><fieldset class=\"fieldset-input is-2\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field\" id=\"input-1\"><label for=\"field-1\">Sex<\/label><div class=\"grid grid-cols-1\"><select id=\"field-1\" name=\"sex\"><option value=\"male\" selected>Male<\/option><option value=\"female\">Female<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><div class=\"field\" id=\"input-2\"><label for=\"field-2\">Age<\/label><input type=\"text\" name=\"age\" id=\"field-2\" aria-describedby=\"calc-unit-2 calc-info-2\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"2\" max=\"110\" value=\"35\"\/><div class=\"unit\" id=\"calc-unit-2\">years<\/div><small id=\"calc-info-2\">Under 14? The Peters pediatric formula is used instead of the adult equations.<\/small><\/div><div class=\"field has-term\" id=\"input-3\"><label for=\"field-3\">Weight (W)<\/label><div class=\"term\">W<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><div class=\"field-group\"><input type=\"text\" name=\"weight_w\" id=\"field-3\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"10\" value=\"80\"\/><div class=\"grid grid-cols-1\"><select id=\"field-4\" name=\"unit\" aria-label=\"Unit\"><option value=\"kg\" selected>kg<\/option><option value=\"lb\">lb<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><\/div><div class=\"field has-term\" id=\"input-4\"><label for=\"field-5\">Height (H<\/label><div class=\"term\">H<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><div class=\"field-group\"><input type=\"text\" name=\"height_h\" id=\"field-5\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"60\" value=\"180\"\/><div class=\"grid grid-cols-1\"><select id=\"field-6\" name=\"unit\" aria-label=\"Unit\"><option value=\"cm\" selected>cm<\/option><option value=\"in\">in<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><\/div><div class=\"field has-term\" id=\"input-5\"><label for=\"field-7\">Body fat % (optional)<\/label><div class=\"term\">BF<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"body_fat_optional\" id=\"field-7\" aria-describedby=\"calc-info-7\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 20\" min=\"0\" max=\"100\"\/><small id=\"calc-info-7\">If you know your body fat percentage, LBM is calculated directly as W \u00d7 (1 \u2212 BF%).<\/small><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"67423\">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> Your Lean Body Mass Estimate<\/h3><div class=\"result-box\"><div class=\"field-result\" id=\"output-1\"><span class=\"field-title\"><span>LBM \u2014 Boer formula<\/span><\/span><span class=\"field-value\" id=\"result-1\" data-unit=\"kg\"><\/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-2\"><span class=\"field-title\"><span>LBM \u2014 James formula<\/span><\/span><span class=\"field-value\" id=\"result-2\" data-unit=\"kg\"><\/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>LBM \u2014 Hume formula<\/span><\/span><span class=\"field-value\" id=\"result-3\" data-unit=\"kg\"><\/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-4\"><span class=\"field-title\"><span>LBM \u2014 Peters formula (children)<\/span><\/span><span class=\"field-value\" id=\"result-4\" data-unit=\"kg\"><\/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-5\"><span class=\"field-title\"><span>LBM from your body fat %<\/span><\/span><span class=\"field-value\" id=\"result-5\" data-unit=\"kg\"><\/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-6\"><span class=\"field-title\"><span>Average LBM<\/span><\/span><span class=\"field-value\" id=\"result-6\" data-unit=\"kg\"><\/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-7\"><span class=\"field-title\"><span>Implied body fat %<\/span><\/span><span class=\"field-value\" id=\"result-7\" data-unit=\"%\"><\/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-8\"><span class=\"field-title\"><span>Fat mass<\/span><\/span><span class=\"field-value\" id=\"result-8\" data-unit=\"kg\"><\/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-9\"><span class=\"field-title\"><span>About This Estimate<\/span><\/span><span class=\"field-value\" id=\"result-9\"><\/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=\"67423\" 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>Lean Body Mass 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\\[ \\text{Boer: } LBM = \\begin{cases} 0.407\\,W + 0.267\\,H - 19.2 &amp; \\text{(male)} \\\\ 0.252\\,W + 0.473\\,H - 48.3 &amp; \\text{(female)} \\end{cases} \\\\\\ \\text{James: } LBM = \\begin{cases} 1.1\\,W - 128\\,(W\/H)^2 &amp; \\text{(male)} \\\\ 1.07\\,W - 148\\,(W\/H)^2 &amp; \\text{(female)} \\end{cases} \\\\\\ \\text{Hume: } LBM = \\begin{cases} 0.32810\\,W + 0.33929\\,H - 29.5336 &amp; \\text{(male)} \\\\ 0.29569\\,W + 0.41813\\,H - 43.2933 &amp; \\text{(female)} \\end{cases} \\\\\\ \\text{Peters (children): } LBM = 3.8 \\times 0.0215 \\times W^{0.6462} \\times H^{0.7236} \\\\\\ \\text{From body fat: } LBM = W\\left(1 - \\frac{BF}{100}\\right) \\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(W\\) \u2014 total body weight in kilograms<\/li>\n<li>\\(H\\) \u2014 height in centimetres<\/li>\n<li>\\(BF\\) \u2014 body fat percentage (0\u2013100)<\/li>\n<li>\\(LBM\\) \u2014 lean body mass in kilograms<\/li>\n<\/ul>\n<p>Each adult formula estimates lean body mass from weight and height with different regression coefficients. When no body fat percentage is entered, the calculator averages the applicable formulas; when one is entered, the direct body-fat equation takes priority because it reflects your actual composition.<\/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>Lean Body Mass \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> a 35-year-old man weighing 80 kg at a height of 180 cm, with no measured body fat percentage.<\/p>\n<p>\\[ LBM_{Boer} = 0.407 \\times 80 + 0.267 \\times 180 - 19.2 = 61.4 \\text{ kg} \\]<\/p>\n<p>\\[ LBM_{James} = 1.1 \\times 80 - 128 \\times (80\/180)^2 = 62.7 \\text{ kg} \\]<\/p>\n<p>\\[ LBM_{Hume} = 0.32810 \\times 80 + 0.33929 \\times 180 - 29.5336 = 57.8 \\text{ kg} \\]<\/p>\n<p>\\[ LBM_{avg} = \\frac{61.4 + 62.7 + 57.8}{3} \\approx 60.6 \\text{ kg} \\]<\/p>\n<p><strong>Result:<\/strong> average lean body mass \u2248 60.6 kg, fat mass \u2248 19.4 kg, implied body fat \u2248 24.2%.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to Use the Calculator<\/h2>\n<ol>\n<li>Select your <strong>Sex<\/strong> \u2014 male or female. The adult formulas use different coefficients for each.<\/li>\n<li>Enter your <strong>Age<\/strong> in years (between 2 and 110). At age 13 or younger, the calculator automatically switches to the Peters pediatric formula.<\/li>\n<li>Enter your <strong>Weight (W)<\/strong> and choose <strong>kg<\/strong> or <strong>lb<\/strong> as the unit.<\/li>\n<li>Enter your <strong>Height (H)<\/strong> and choose <strong>cm<\/strong> or <strong>in<\/strong> as the unit.<\/li>\n<li>If you know it, enter your <strong>Body fat % (optional)<\/strong>. This overrides the formula estimates and gives a direct calculation.<\/li>\n<li>Read the results: each formula's LBM, the average LBM, the implied body fat percentage, and your fat mass in kilograms.<\/li>\n<\/ol>\n<h2>What Is Lean Body Mass?<\/h2>\n<p>Lean body mass (LBM) is everything in your body that is not fat: skeletal muscle, bones, organs, skin, and body water. It is not the same as muscle mass alone \u2014 muscle is the largest single component of LBM, but water alone makes up roughly 60\u201370% of it. Because fat tissue contributes relatively little to metabolism compared with lean tissue, LBM is a better basis than total weight for many calculations in medicine, nutrition and sport science.<\/p>\n<p>Doctors use LBM to size drug dosages (some anesthetics and chemotherapy agents are dosed per kg of lean mass), to assess malnutrition and muscle wasting, and to interpret kidney function. In fitness, LBM is central to tracking progress: if your weight stays the same but your LBM rises, you have replaced fat with muscle. It is also the reference for protein targets \u2014 a common guideline is 1.6\u20132.2 g of protein per kg of lean mass, which you can put into practice with our <a href=\"https:\/\/wpcalc.com\/en\/beauty\/macro-calculator-protein-carbs-and-fat\/\">Macros Calculator<\/a>.<\/p>\n<p>The three adult equations used here come from clinical studies. Boer's formula (1984) was derived from body water measurements and is widely used in pharmacokinetics. James' formula (1976) underlies many hospital nutrition standards, and Hume's formula (1966) was developed from total body potassium and water studies. They typically agree within 10\u201315% for average adults, which is why the calculator shows all of them plus their average \u2014 the spread gives you a sense of the estimate's uncertainty.<\/p>\n<p>To interpret your result: a typical healthy adult woman has an LBM of roughly 35\u201345 kg and a man roughly 50\u201365 kg, but values outside these ranges can be perfectly healthy. What matters more is the trend over time and the ratio of lean to total mass. If you want to quantify your build more precisely, combine your LBM with height in our <a href=\"https:\/\/wpcalc.com\/en\/fat-free-mass-index-calculator\/\">Fat-Free Mass Index (FFMI) Calculator<\/a>.<\/p>\n<h2>Assumptions and Limitations<\/h2>\n<ul>\n<li><strong>Weight and height cannot reveal composition.<\/strong> All four formulas estimate LBM statistically from a reference population. Two people with the same inputs get the same answer, even if one is muscular and the other is not.<\/li>\n<li><strong>A body fat measurement is always better.<\/strong> If you know your body fat percentage, enter it \u2014 the result is then a direct calculation, not an estimate. You can find yours with our <a href=\"https:\/\/wpcalc.com\/en\/body-fat-calculator\/\">Body Fat Calculator<\/a>.<\/li>\n<li><strong>Accuracy decreases at body extremes.<\/strong> The Boer, James and Hume equations were fitted on people near average weight. In very muscular individuals they underestimate LBM, and in people with obesity James' formula in particular can fail; some drug-dosing guidelines cap the weight used in such equations.<\/li>\n<li><strong>Children use a different equation.<\/strong> Under age 14, the adult formulas do not apply; the calculator uses the Peters formula, which was derived from total body water studies in pediatric patients.<\/li>\n<li><strong>Don't confuse LBM with fat-free mass.<\/strong> They differ slightly: fat-free mass excludes all fat, while lean body mass includes a small amount of essential lipid (about 2\u20133% of body weight). For everyday purposes the two are used interchangeably.<\/li>\n<li><strong>Fluid status matters.<\/strong> Because water is the largest part of LBM, dehydration or oedema shifts the result. Weigh yourself under consistent conditions, ideally in the morning, for comparable numbers over time.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Estimate your lean body mass (LBM) from weight, height and sex using the Boer, James, Hume and Peters formulas, or get an exact value from your body fat percentage.<\/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":[2],"tags":[12],"class_list":["post-67423","post","type-post","status-publish","format-standard","hentry","category-beauty","tag-appearance"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/67423","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=67423"}],"version-history":[{"count":1,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/67423\/revisions"}],"predecessor-version":[{"id":67424,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/67423\/revisions\/67424"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=67423"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=67423"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=67423"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}