{"id":66855,"date":"2026-10-13T09:52:24","date_gmt":"2026-10-13T06:52:24","guid":{"rendered":"https:\/\/wpcalc.com\/en\/?p=66855"},"modified":"2026-10-26T09:23:15","modified_gmt":"2026-10-26T06:23:15","slug":"anion-gap-calculator","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/medical\/anion-gap-calculator\/","title":{"rendered":"Anion Gap Calculator \u2013 With Albumin Correction"},"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\">Calculate the Anion Gap from Your Electrolyte Results<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"66855\" data-favorite-title=\"Anion Gap\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/medical\/anion-gap-calculator\/\" data-favorite-excerpt=\"Enter your sodium, chloride and bicarbonate (CO\u2082) values to calculate the anion gap, with optional albumin correction. Helps interpret metabolic acidosis from a standard chemistry panel.\" aria-label=\"Add to Favorites\" data-favorite-icon=\"icon icon-flask\">\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\/medical\/anion-gap-calculator\/\" method=\"POST\" class=\"calculator\" id=\"calculator-66855\" data-post=\"66855\"><fieldset class=\"fieldset-input is-1\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field has-term\" id=\"input-1\"><label for=\"field-1\">Sodium (Na\u207a)<\/label><div class=\"term\">Na\u207a<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"sodium_na\" id=\"field-1\" aria-describedby=\"calc-unit-1 calc-info-1\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 140\" min=\"100\" max=\"180\" value=\"140\"\/><div class=\"unit\" id=\"calc-unit-1\">mEq\/L<\/div><small id=\"calc-info-1\">Serum sodium from your chemistry panel<\/small><\/div><div class=\"field has-term\" id=\"input-2\"><label for=\"field-2\">Chloride (Cl\u207b)<\/label><div class=\"term\">Cl\u207b<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"chloride_cl\" id=\"field-2\" aria-describedby=\"calc-unit-2 calc-info-2\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 104\" min=\"60\" max=\"130\" value=\"104\"\/><div class=\"unit\" id=\"calc-unit-2\">mEq\/L<\/div><small id=\"calc-info-2\">Serum chloride from your chemistry panel<\/small><\/div><div class=\"field has-term\" id=\"input-3\"><label for=\"field-3\">Bicarbonate (HCO\u2083\u207b)<\/label><div class=\"term\">HCO\u2083\u207b<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"bicarbonate_hco\" id=\"field-3\" aria-describedby=\"calc-unit-3 calc-info-3\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 24\" min=\"1\" max=\"60\" value=\"24\"\/><div class=\"unit\" id=\"calc-unit-3\">mEq\/L<\/div><small id=\"calc-info-3\">Also reported as CO\u2082 or \u201ctotal CO\u2082\u201d on many lab reports<\/small><\/div><div class=\"field is-checkbox\" id=\"input-4\"><input type=\"checkbox\" id=\"field-4\" value=\"1\" checked=\"checked\"\/><label for=\"field-4\">Correct for albumin (recommended if albumin is known)<\/label><\/div><div class=\"field has-term\" id=\"input-5\"><label for=\"field-5\">Serum albumin<\/label><div class=\"term\">Alb<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"serum_albumin\" id=\"field-5\" aria-describedby=\"calc-unit-5 calc-info-5\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 4.0\" min=\"0.5\" max=\"6\" value=\"3\"\/><div class=\"unit\" id=\"calc-unit-5\">g\/dL<\/div><small id=\"calc-info-5\">Leave the checkbox unticked if albumin was not measured<\/small><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"66855\">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 Anion Gap<\/h3><div class=\"result-box\"><div class=\"field-result\" id=\"output-1\"><span class=\"field-title\"><span>Anion gap<\/span><span class=\"result-term\">AG<\/span><\/span><span class=\"field-value\" id=\"result-1\" data-unit=\"mEq\/L\"><\/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>Albumin-corrected anion gap<\/span><span class=\"result-term\">AG corr<\/span><\/span><span class=\"field-value\" id=\"result-2\" data-unit=\"mEq\/L\"><\/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-3\"><span class=\"field-title\"><span>What this means<\/span><\/span><span class=\"field-value\" id=\"result-3\"><\/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=\"66855\" 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>Anion Gap 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\\[ AG = Na^+ - (Cl^- + HCO_3^-) \\]\n\\[ AG_{corr} = AG + 2.5 \\times (4.0 - \\text{albumin in g\/dL}) \\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(Na^+\\) \u2014 serum sodium concentration (mEq\/L)<\/li>\n<li>\\(Cl^-\\) \u2014 serum chloride concentration (mEq\/L)<\/li>\n<li>\\(HCO_3^-\\) \u2014 serum bicarbonate concentration (mEq\/L), often reported as \u201cCO\u2082\u201d or \u201ctotal CO\u2082\u201d<\/li>\n<li>\\(2.5\\) \u2014 mEq\/L added to the gap for every 1 g\/dL that albumin lies below 4.0 g\/dL<\/li>\n<\/ul>\n<p>The first formula measures the difference between routinely measured cations and anions \u2014 the \u201cgap\u201d that reflects unmeasured anions such as albumin, lactate and ketoacids. The second (Emmett) correction adjusts for low albumin, which otherwise masks an elevated gap.<\/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>Anion Gap \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> a chemistry panel shows sodium 140 mEq\/L, chloride 104 mEq\/L, bicarbonate 24 mEq\/L, and albumin 3.0 g\/dL.<\/p>\n<p>\\[ AG = 140 - (104 + 24) = 140 - 128 = 12 \\text{ mEq\/L} \\]<\/p>\n<p>\\[ AG_{corr} = 12 + 2.5 \\times (4.0 - 3.0) = 12 + 2.5 = 14.5 \\text{ mEq\/L} \\]<\/p>\n<p><strong>Result:<\/strong> anion gap 12 mEq\/L; albumin-corrected anion gap 14.5 mEq\/L \u2014 mildly elevated, mainly revealed once the low albumin is taken into account.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to Use the Anion Gap Calculator<\/h2>\n<ol>\n<li>Enter your <strong>Sodium (Na\u207a)<\/strong> value from the chemistry panel (basic metabolic panel), in mEq\/L.<\/li>\n<li>Enter your <strong>Chloride (Cl\u207b)<\/strong> value in mEq\/L.<\/li>\n<li>Enter your <strong>Bicarbonate (HCO\u2083\u207b)<\/strong> value in mEq\/L. On many lab reports this appears as \u201cCO\u2082\u201d or \u201ctotal CO\u2082\u201d \u2014 use that number.<\/li>\n<li>If albumin was measured, keep <strong>\u201cCorrect for albumin\u201d<\/strong> ticked and enter your <strong>Serum albumin<\/strong> in g\/dL. If it was not measured, untick the checkbox.<\/li>\n<li>Read the <strong>Anion gap<\/strong>, the <strong>Albumin-corrected anion gap<\/strong>, and the plain-language interpretation below them.<\/li>\n<\/ol>\n<h2>What Is the Anion Gap?<\/h2>\n<p>The anion gap is a calculated value from a routine blood chemistry panel. Blood plasma must remain electrically neutral: the total positive charge of cations equals the total negative charge of anions. Routine panels measure sodium, chloride and bicarbonate but not every charged particle \u2014 proteins, organic acids, phosphate and others are \u201cunmeasured.\u201d The anion gap estimates the size of this unmeasured fraction:<\/p>\n<p>\\[ \\text{measured cations} - \\text{measured anions} \\approx \\text{unmeasured anions} - \\text{unmeasured cations} \\]<\/p>\n<p>In a healthy person the gap is mostly accounted for by albumin, so a normal result is roughly 3\u201311 mEq\/L when potassium is excluded. When acids accumulate in the blood \u2014 lactate in shock, ketones in diabetic ketoacidosis, toxins in methanol poisoning \u2014 the extra unmeasured anions push the gap upward. A rising anion gap is therefore a sensitive flag for certain types of <em>metabolic acidosis<\/em> and often appears before the cause is obvious.<\/p>\n<p>The main clinical value of the anion gap is classification: it divides metabolic acidosis into <strong>high-anion-gap<\/strong> causes (lactic acidosis, ketoacidosis, renal failure, toxins) and <strong>normal-anion-gap<\/strong> causes (diarrhea, renal tubular acidosis), which narrows the differential diagnosis considerably. Because it is derived from three other measurements, it carries no extra cost and no extra blood draw.<\/p>\n<p>Albumin is the single largest contributor to the normal gap. In hypoalbuminemia \u2014 common in chronic illness, liver disease and critical care \u2014 each 1 g\/dL drop in albumin lowers the measured gap by about 2.5 mEq\/L, potentially hiding a dangerous acidosis. That is why the albumin correction is recommended whenever albumin is known, and why the calculator uses the corrected value for interpretation.<\/p>\n<h2>Interpreting Your Result<\/h2>\n<p>Typical reference ranges (without potassium):<\/p>\n<table>\n<thead>\n<tr>\n<th>Anion gap<\/th>\n<th>Interpretation<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>3\u201311 mEq\/L<\/td>\n<td>Normal<\/td>\n<\/tr>\n<tr>\n<td>&gt; 11, up to ~19 mEq\/L<\/td>\n<td>Mildly elevated \u2014 possible high-anion-gap acidosis (lactate, ketones, CKD, drugs)<\/td>\n<\/tr>\n<tr>\n<td>~19\u201330 mEq\/L<\/td>\n<td>Clearly elevated \u2014 high-anion-gap metabolic acidosis likely, needs medical evaluation<\/td>\n<\/tr>\n<tr>\n<td>\u2265 30 mEq\/L<\/td>\n<td>Markedly elevated \u2014 consider severe lactic acidosis, toxic alcohols or salicylates; urgent evaluation<\/td>\n<\/tr>\n<tr>\n<td>&lt; 3 mEq\/L<\/td>\n<td>Low \u2014 consider marked hypoalbuminemia, paraproteinemia (e.g. myeloma), bromide, or lab error<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>A result outside the normal range is not a diagnosis. It must be read together with bicarbonate, pH (if available), the clinical picture and often a lactate or ketone measurement.<\/p>\n<h2>Limitations and Practical Tips<\/h2>\n<ul>\n<li><strong>Laboratory variation.<\/strong> Reference ranges differ between labs, and some include potassium in the calculation (typical range 10\u201320 mEq\/L). Compare your result to the range printed on your own report when possible.<\/li>\n<li><strong>Bicarbonate nomenclature.<\/strong> If your report shows \u201cCO\u2082\u201d or \u201ctotal CO\u2082\u201d rather than bicarbonate, use that value \u2014 it is essentially the same measurement for this purpose.<\/li>\n<li><strong>A normal gap does not exclude acidosis.<\/strong> Normal-anion-gap (hyperchloremic) acidosis, such as diarrhea or renal tubular acidosis, can occur with a completely normal anion gap.<\/li>\n<li><strong>Single snapshot.<\/strong> Electrolytes change quickly in acute illness. Trends across repeated panels are more informative than one value.<\/li>\n<li><strong>Not a diagnostic tool.<\/strong> This calculator provides information for discussion with a clinician; it cannot replace medical judgment or further testing.<\/li>\n<\/ul>\n<p>If a toxic alcohol ingestion is suspected, the anion gap is often paired with the <a href=\"https:\/\/wpcalc.com\/en\/medical\/serum-osmolality-calculator\/\">Serum Osmolality Calculator<\/a> to detect a coexisting osmolar gap. Chronic kidney disease is a common cause of a persistently elevated gap \u2014 the <a href=\"https:\/\/wpcalc.com\/en\/medical\/egfr-calculator-ckd-epi-2021\/\">eGFR (CKD-EPI 2021) Calculator<\/a> can help assess kidney function, and the <a href=\"https:\/\/wpcalc.com\/en\/medical\/qsofa-score-calculator\/\">qSOFA Score Calculator<\/a> is useful when sepsis (a major cause of lactic acidosis) is a concern.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Enter your sodium, chloride and bicarbonate (CO\u2082) values to calculate the anion gap, with optional albumin correction. Helps interpret metabolic acidosis from a standard chemistry panel.<\/p>\n","protected":false},"author":3168,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[8],"tags":[50],"class_list":["post-66855","post","type-post","status-publish","format-standard","hentry","category-medical","tag-diagnostics"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/66855","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=66855"}],"version-history":[{"count":2,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/66855\/revisions"}],"predecessor-version":[{"id":67527,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/66855\/revisions\/67527"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=66855"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=66855"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=66855"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}