{"id":66496,"date":"2026-10-06T17:31:01","date_gmt":"2026-10-06T14:31:01","guid":{"rendered":"https:\/\/wpcalc.com\/en\/?p=66496"},"modified":"2026-10-06T17:31:01","modified_gmt":"2026-10-06T14:31:01","slug":"henderson-hasselbalch-calculator","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/chemistry\/henderson-hasselbalch-calculator\/","title":{"rendered":"Henderson\u2013Hasselbalch 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 the pH or the Required Ratio of an Acid\u2013Base Buffer<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"66496\" data-favorite-title=\"Henderson\u2013Hasselbalch\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/chemistry\/henderson-hasselbalch-calculator\/\" data-favorite-excerpt=\"Calculate the pH of an acid\u2013base buffer from the pKa and the amounts of acid and conjugate base, or find the base-to-acid ratio needed to hit a target pH. Enter pKa and concentrations to get the result instantly.\" 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\/chemistry\/henderson-hasselbalch-calculator\/\" method=\"POST\" class=\"calculator\" id=\"calculator-66496\" data-post=\"66496\"><fieldset class=\"fieldset-input is-1\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field\" id=\"input-1\"><label for=\"field-1\">What to Calculate<\/label><div class=\"grid grid-cols-1\"><select id=\"field-1\" name=\"what_to_calculate\"><option value=\"ph\" selected>Buffer pH from acid and base amounts<\/option><option value=\"ratio\">Required base-to-acid ratio for a target pH<\/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 has-term\" id=\"input-2\"><label for=\"field-2\">pKa of the Acid (HA)<\/label><div class=\"term\">pKa<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"number\" name=\"pka_of_the_acid_ha\" id=\"field-2\" aria-describedby=\"calc-info-2\" placeholder=\"e.g. 4.76\" min=\"-2\" max=\"16\" step=\"0.01\" value=\"4.76\"\/><small id=\"calc-info-2\">Negative log of the acid dissociation constant (e.g. 4.76 for acetic acid)<\/small><\/div><div class=\"field has-term\" id=\"input-3\"><label for=\"field-3\">Amount of Acid Form (HA)<\/label><div class=\"term\">[HA]<\/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=\"amount_of_acid_form_ha\" id=\"field-3\" aria-describedby=\"calc-info-3\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 0.1\" min=\"0\" value=\"0.1\"\/><div class=\"grid grid-cols-1\"><select id=\"field-4\" name=\"unit\" aria-label=\"Unit\"><option value=\"mol_l\" selected>mol\/L<\/option><option value=\"mmol_l\">mmol\/L<\/option><option value=\"umol_l\">\u00b5mol\/L<\/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><small id=\"calc-info-3\">Concentration or amount of the weak acid in the buffer<\/small><\/div><div class=\"field has-term\" id=\"input-4\"><label for=\"field-5\">Amount of Base Form (A\u207b)<\/label><div class=\"term\">[A\u207b]<\/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=\"amount_of_base_form_a\" id=\"field-5\" aria-describedby=\"calc-info-5\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 0.1\" min=\"0\" value=\"0.1\"\/><div class=\"grid grid-cols-1\"><select id=\"field-6\" name=\"unit\" aria-label=\"Unit\"><option value=\"mol_l\" selected>mol\/L<\/option><option value=\"mmol_l\">mmol\/L<\/option><option value=\"umol_l\">\u00b5mol\/L<\/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><small id=\"calc-info-5\">Concentration or amount of the conjugate base (e.g. acetate)<\/small><\/div><div class=\"field has-term\" id=\"input-5\" hidden><label for=\"field-7\">Target pH<\/label><div class=\"term\">pH<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"target_ph\" id=\"field-7\" aria-describedby=\"calc-info-7\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 7.4\" min=\"0\" max=\"14\" value=\"7.4\"\/><small id=\"calc-info-7\">The pH the buffer should reach<\/small><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"66496\">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> Buffer Results<\/h3><div class=\"result-box\"><div class=\"field-result\" id=\"output-1\"><span class=\"field-title\"><span>Buffer pH<\/span><span class=\"result-term\">pH<\/span><\/span><span class=\"field-value\" id=\"result-1\" data-unit=\"pH\"><\/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>Base-to-Acid Ratio [A\u207b]\/[HA]<\/span><span class=\"result-term\">[A\u207b]\/[HA]<\/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>Acid-to-Base Ratio [HA]\/[A\u207b]<\/span><span class=\"result-term\">[HA]\/[A\u207b]<\/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 class=\"field-result is-column\" id=\"output-4\"><span class=\"field-title\"><span>Details<\/span><\/span><span class=\"field-value\" id=\"result-4\"><\/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=\"66496\" 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>Henderson\u2013Hasselbalch 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{pH} = \\text{p}K_a + \\log_{10}\\!\\left( \\frac{[\\text{A}^-]}{[\\text{HA}]} \\right) \\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(\\text{pH}\\) \u2014 the hydrogen ion potential of the buffer solution<\/li>\n<li>\\(\\text{p}K_a\\) \u2014 the negative logarithm of the acid dissociation constant, \\(-\\log_{10} K_a\\)<\/li>\n<li>\\([\\text{A}^-]\\) \u2014 concentration (or amount) of the conjugate base form<\/li>\n<li>\\([\\text{HA}]\\) \u2014 concentration (or amount) of the weak acid form<\/li>\n<\/ul>\n<p>The equation states that the pH of a buffer equals the pKa of the weak acid plus the logarithm of the ratio of conjugate base to acid. Rearranged, it also lets you solve for the ratio required to reach any target pH: \\([\\text{A}^-]\/[\\text{HA}] = 10^{\\text{pH} - \\text{p}K_a}\\).<\/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>Henderson\u2013Hasselbalch \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example 1 (buffer pH):<\/strong> a buffer contains 0.1 mol\/L acetic acid (pKa = 4.76) and 0.1 mol\/L acetate.<\/p>\n<p>\\[ \\text{pH} = 4.76 + \\log_{10}\\!\\left( \\frac{0.1}{0.1} \\right) = 4.76 + \\log_{10}(1) = 4.76 + 0 \\]<\/p>\n<p><strong>Result:<\/strong> pH = 4.76. When the acid and base forms are equal, the pH always equals the pKa.<\/p>\n<p><strong>Example 2 (required ratio):<\/strong> using the same acid, you want the buffer at pH 5.40 with [HA] = 0.1 mol\/L.<\/p>\n<p>\\[ \\frac{[\\text{A}^-]}{[\\text{HA}]} = 10^{5.40 - 4.76} = 10^{0.64} \\approx 4.37 \\]<\/p>\n<p><strong>Result:<\/strong> you need about 0.437 mol\/L of acetate \u2014 roughly 4.37 parts of base form for every 1 part of acid form.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to Use the Calculator<\/h2>\n<ol>\n<li>Open <strong>What to Calculate<\/strong> and choose either <em>Buffer pH from acid and base amounts<\/em> or <em>Required base-to-acid ratio for a target pH<\/em>. The input fields adapt automatically: in ratio mode, the base amount is hidden and the <strong>Target pH<\/strong> field appears.<\/li>\n<li>Enter the <strong>pKa of the Acid (HA)<\/strong>. For acetic acid this is 4.76; for any other acid, look up its \\(K_a\\) and take \\(-\\log_{10} K_a\\) if needed.<\/li>\n<li>Enter the <strong>Amount of Acid Form (HA)<\/strong> and pick the unit (mol\/L, mmol\/L or \u00b5mol\/L) from the dropdown.<\/li>\n<li>In pH mode, also enter the <strong>Amount of Base Form (A\u207b)<\/strong> with its unit. In ratio mode, enter the <strong>Target pH<\/strong> instead.<\/li>\n<li>Read the results: the buffer pH (in pH mode), the base-to-acid ratio \\([\\text{A}^-]\/[\\text{HA}]\\), its inverse, and a note telling you whether the ratio lies within the effective 0.1\u201310 buffering range.<\/li>\n<\/ol>\n<h2>What the Henderson\u2013Hasselbalch Equation Describes<\/h2>\n<p>The Henderson\u2013Hasselbalch equation describes the behavior of buffer solutions \u2014 mixtures of a weak acid and its conjugate base (or a weak base and its conjugate acid) that resist changes in pH when small amounts of strong acid or base are added. It follows directly from the equilibrium expression \\(K_a = [\\text{H}^+][\\text{A}^-]\/[\\text{HA}]\\) by taking the negative logarithm of both sides. Because the approximation requires both acid and base forms to be present in significant amounts, the equation is a staple of general chemistry, biochemistry and pharmacy.<\/p>\n<p>The most useful insight it gives is the relationship between pH and pKa. When \\([\\text{A}^-] = [\\text{HA}]\\), the ratio is 1, the logarithm is 0, and pH = pKa exactly \u2014 this is the half-equivalence point of a titration. Each tenfold change in the base-to-acid ratio shifts the pH by exactly one unit: a 10:1 ratio puts the pH one unit above the pKa, and a 1:10 ratio puts it one unit below.<\/p>\n<p>Interpreting the result matters as much as computing it. A buffer is most effective when the pH is within \u00b11 unit of the pKa, which corresponds to a \\([\\text{A}^-]\/[\\text{HA}]\\) ratio between 0.1 and 10. Outside that window, one component is nearly exhausted, and the solution loses its ability to neutralize added acid or base in one direction. If your target pH falls far from the pKa, the practical fix is to pick a different buffer system \u2014 for example, phosphate near pH 7.2 or Tris near pH 8.1.<\/p>\n<p>The equation also works for the basic form: for a weak base \\(\\text{B}\\) and its conjugate acid \\(\\text{BH}^+\\), the same relationship holds with \\(\\text{p}K_a\\) of the conjugate acid. In practice you can treat every buffer as an acid\/base conjugate pair and use the calculator unchanged.<\/p>\n<h2>Assumptions, Limitations and Practical Tips<\/h2>\n<ul>\n<li><strong>Equilibrium concentrations vs. added amounts.<\/strong> The equation assumes that the added (analytical) amounts of HA and A\u207b equal their equilibrium concentrations. This is accurate when both forms are present at appreciable levels and the acid is weak, but breaks down for very dilute buffers (below about 10\u207b\u00b3 mol\/L) or extremely weak or strong acids.<\/li>\n<li><strong>Activity vs. concentration.<\/strong> The rigorous form uses activities rather than molar concentrations. At ionic strengths above roughly 0.1 mol\/L, activity coefficients deviate noticeably from 1, so the predicted pH can be off by 0.1\u20130.3 units. Check the <a href=\"https:\/\/wpcalc.com\/en\/chemistry\/ionic-strength-calculator\/\">ionic strength of your solution<\/a> to judge whether this correction matters.<\/li>\n<li><strong>Valid pH range.<\/strong> The equation is unreliable below about pH 2 and above about pH 12, where water autoionization and activity effects become large. For direct pH computations from a strong acid or base concentration, use the dedicated <a href=\"https:\/\/wpcalc.com\/en\/chemistry\/ph-calculator\/\">pH calculator<\/a>.<\/li>\n<li><strong>Units cancel in the ratio.<\/strong> Because only the ratio \\([\\text{A}^-]\/[\\text{HA}]\\) matters, both amounts may be entered in moles, concentrations, or even millimoles as long as they use the same unit. The calculator converts units automatically.<\/li>\n<li><strong>Temperature dependence.<\/strong> pKa values shift with temperature (acetic acid changes by only a small amount, but Tris shifts by about \u22120.03 pH units per \u00b0C). Use a pKa measured at your working temperature for precise work.<\/li>\n<li><strong>Related tasks.<\/strong> To find where a buffer's pH equals the pKa during a titration, see the <a href=\"https:\/\/wpcalc.com\/en\/chemistry\/acid-base-titration-calculator\/\">acid\u2013base titration calculator<\/a>; to convert a mass of a salt into the molar amount you enter here, use the <a href=\"https:\/\/wpcalc.com\/en\/chemistry\/molarity-calculator\/\">molarity calculator<\/a>.<\/li>\n<\/ul>\n<h2>Common Buffer Systems and Their pKa Values<\/h2>\n<table>\n<thead>\n<tr>\n<th>Buffer pair<\/th>\n<th>pKa (25 \u00b0C)<\/th>\n<th>Useful pH range<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Acetic acid \/ acetate<\/td>\n<td>4.76<\/td>\n<td>3.8 \u2013 5.8<\/td>\n<\/tr>\n<tr>\n<td>Carbonic acid \/ bicarbonate<\/td>\n<td>6.35<\/td>\n<td>5.4 \u2013 7.4<\/td>\n<\/tr>\n<tr>\n<td>Dihydrogen phosphate \/ hydrogen phosphate<\/td>\n<td>7.21<\/td>\n<td>6.2 \u2013 8.2<\/td>\n<\/tr>\n<tr>\n<td>Tris\u00b7H\u207a \/ Tris<\/td>\n<td>8.06<\/td>\n<td>7.1 \u2013 9.1<\/td>\n<\/tr>\n<tr>\n<td>Ammonium \/ ammonia<\/td>\n<td>9.25<\/td>\n<td>8.3 \u2013 10.3<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"excerpt":{"rendered":"<p>Calculate the pH of an acid\u2013base buffer from the pKa and the amounts of acid and conjugate base, or find the base-to-acid ratio needed to hit a target pH. Enter pKa and concentrations to get the result instantly.<\/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":[58],"class_list":["post-66496","post","type-post","status-publish","format-standard","hentry","category-chemistry","tag-buffers"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/66496","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=66496"}],"version-history":[{"count":1,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/66496\/revisions"}],"predecessor-version":[{"id":66497,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/66496\/revisions\/66497"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=66496"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=66496"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=66496"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}