{"id":67168,"date":"2026-10-20T09:51:49","date_gmt":"2026-10-20T06:51:49","guid":{"rendered":"https:\/\/wpcalc.com\/en\/?p=67168"},"modified":"2026-10-20T09:51:49","modified_gmt":"2026-10-20T06:51:49","slug":"credit-card-interest-calculator","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/finance\/credit-card-interest-calculator\/","title":{"rendered":"Credit Card Interest 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 Interest for a Billing Cycle<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"67168\" data-favorite-title=\"Credit Card Interest\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/finance\/credit-card-interest-calculator\/\" data-favorite-excerpt=\"Estimate credit card interest for a billing cycle. Enter your APR and cycle length, then provide either your average daily balance or a starting balance and transactions.\" aria-label=\"Add to Favorites\" data-favorite-icon=\"icon icon-rate-up\">\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\/finance\/credit-card-interest-calculator\/\" method=\"POST\" class=\"calculator\" id=\"calculator-67168\" data-post=\"67168\"><fieldset class=\"fieldset-input is-1\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field\" id=\"input-1\"><label for=\"field-1\">Balance method<\/label><div class=\"grid grid-cols-1\"><select id=\"field-1\" name=\"balance_method\"><option value=\"average\" selected>Enter average daily balance<\/option><option value=\"transactions\">Calculate from transactions<\/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\">Annual percentage rate (APR)<\/label><input type=\"text\" name=\"annual_percentage_rate_apr\" id=\"field-2\" aria-describedby=\"calc-unit-2\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"0\" max=\"1000\" value=\"24.99\"\/><div class=\"unit\" id=\"calc-unit-2\">%<\/div><\/div><div class=\"field\" id=\"input-3\"><label for=\"field-3\">Days in billing cycle<\/label><input type=\"text\" name=\"days_in_billing_cycle\" id=\"field-3\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"1\" max=\"366\" value=\"30\"\/><\/div><div class=\"field\" id=\"input-4\"><label for=\"field-4\">Average daily balance<\/label><input type=\"text\" name=\"average_daily_balance\" id=\"field-4\" aria-describedby=\"calc-unit-4\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"0\" value=\"1000\"\/><div class=\"unit\" id=\"calc-unit-4\">$<\/div><\/div><div class=\"field\" id=\"input-5\" hidden><label for=\"field-5\">Balance at start of cycle<\/label><input type=\"text\" name=\"balance_at_start_of_cycle\" id=\"field-5\" aria-describedby=\"calc-unit-5 calc-info-5\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"0\" value=\"1000\"\/><div class=\"unit\" id=\"calc-unit-5\">$<\/div><small id=\"calc-info-5\">Balance before any transactions on day 1.<\/small><\/div><div class=\"field\" id=\"input-6\" hidden><label for=\"field-6\">Transactions<\/label><textarea id=\"field-6\" name=\"transactions\">10; 200\n20; -100<\/textarea><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"67168\">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> Estimated Credit Card Interest<\/h3><div class=\"result-box\"><div class=\"field-result\" id=\"output-1\"><span class=\"field-title\"><span>Daily periodic rate<\/span><\/span><span class=\"field-value\" id=\"result-1\" 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-2\"><span class=\"field-title\"><span>Average daily balance<\/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>Interest charged this cycle<\/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\" id=\"output-4\"><span class=\"field-title\"><span>Effective annual rate, monthly compounding<\/span><\/span><span class=\"field-value\" id=\"result-4\" 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-5\"><span class=\"field-title\"><span>Interest per year at the same balance<\/span><\/span><span class=\"field-value\" id=\"result-5\"><\/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-6\"><span class=\"field-title\"><span>Interest comparison and payoff planning<\/span><\/span><span class=\"field-value\" id=\"result-6\"><\/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=\"67168\" 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>Credit Card Interest 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\\[ \\begin{aligned} \\overline{B} &amp;= \\frac{\\sum_{d=1}^{D} B_d}{D} \\\\ I &amp;= \\overline{B}\\times\\frac{a}{365}\\times D \\end{aligned} \\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(I\\) \u2014 estimated interest charged for the billing cycle ($)<\/li>\n<li>\\(\\overline{B}\\) \u2014 average daily balance ($)<\/li>\n<li>\\(B_d\\) \u2014 balance on day \\(d\\), after any transactions entered for that day ($)<\/li>\n<li>\\(D\\) \u2014 number of days in the billing cycle<\/li>\n<li>\\(a\\) \u2014 APR expressed as a decimal; for example, 24.99% is 0.2499<\/li>\n<\/ul>\n<p>The calculator divides the APR by 365 to obtain a daily rate, then applies it to each day\u2019s balance. If you enter an average daily balance directly, it uses that amount without calculating individual daily balances.<\/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>Credit Card Interest \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> using the default average daily balance of $1,000, a 24.99% APR, and a 30-day billing cycle:<\/p>\n<p>\\[ I = \\$1{,}000\\times\\frac{0.2499}{365}\\times30 \\approx \\$20.54 \\]<\/p>\n<p><strong>Result:<\/strong> estimated interest charged this cycle is $20.54. The daily periodic rate is approximately 0.06846575%, and the simple interest estimate for a full year at the same balance is $249.90.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to use the calculator<\/h2>\n<ol>\n<li>Choose a <strong>Balance method<\/strong>. Select <strong>Enter average daily balance<\/strong> if you already know that figure, or <strong>Calculate from transactions<\/strong> to build it from a starting balance and changes during the cycle.<\/li>\n<li>Enter the <strong>Annual percentage rate (APR)<\/strong> shown for the balance you want to estimate. Enter 24.99 for 24.99%, not 0.2499.<\/li>\n<li>Enter <strong>Days in billing cycle<\/strong> as a whole number. Use the length of the particular statement period you are estimating, which may differ from one month to the next.<\/li>\n<li>If you chose the average-balance method, enter <strong>Average daily balance<\/strong>. If you chose transactions, enter <strong>Balance at start of cycle<\/strong> and add 1 to 10 lines under <strong>Transactions<\/strong>, each in the form <code>day; amount<\/code>. For example, <code>10; 200<\/code> adds a $200 purchase on day 10, while <code>20; -100<\/code> records a $100 payment on day 20.<\/li>\n<li>Read <strong>Interest charged this cycle<\/strong> for the main estimate. Check <strong>Average daily balance<\/strong> if you entered transactions, and use the comparison table to see what the same balance and cycle length would cost at other APRs.<\/li>\n<\/ol>\n<h2>What credit card interest measures<\/h2>\n<p>Credit card interest is the cost of carrying a balance. This calculator estimates that cost by applying a daily periodic rate\u2014APR divided by 365\u2014to the balance for each day of a billing cycle. A higher APR, a higher daily balance, or more days in the cycle increases the estimated charge.<\/p>\n<p>The average daily balance captures the timing of purchases and payments. In transaction mode, a change takes effect at the start of the day you enter. With the default transaction entries, a $1,000 starting balance becomes $1,200 on day 10 and $1,100 on day 20. Over 30 days, the average daily balance is $1,103.33 when displayed to cents, and the estimated interest is $22.66. The calculator uses the unrounded average for its interest calculation.<\/p>\n<p>The <strong>Interest per year at the same balance<\/strong> result is the average daily balance multiplied by APR. It is a simple-interest comparison for a balance held constant for 365 days, not a prediction of future statements. The separate <strong>Effective annual rate, monthly compounding<\/strong> shows \\((1+a\/12)^{12}-1\\); it illustrates the effect of monthly compounding and is not used to calculate this cycle\u2019s interest. For a broader explanation of how interest grows when it is added to a balance, see the <a href=\"https:\/\/wpcalc.com\/en\/finance\/compound-interest\/\">Compound Interest Calculator<\/a>.<\/p>\n<h2>Assumptions and practical limits<\/h2>\n<p>This is an estimate, not a reconstruction of your card issuer\u2019s statement. It assumes one APR applies to the entire entered balance and uses a fixed 365-day divisor. Cards may treat purchases, cash advances, and balance transfers differently; promotional rates, fees, grace periods, and the issuer\u2019s posting or rounding rules can also change the amount charged. If a grace period means no purchase interest is due, the calculator\u2019s positive estimate does not override that.<\/p>\n<p>In transaction mode, enter days from 1 through the specified cycle length. Purchases are positive and payments are negative. The calculator does not allow a daily balance below $0, so check a payment that exceeds the outstanding balance. For the most useful estimate, use transaction dates as they affect the balance rather than assuming every payment occurred on the final day.<\/p>\n<p>Comparing APRs here holds the average daily balance and cycle length fixed; it does not account for changes in spending or repayment. If you are weighing a replacement loan against card debt, the <a href=\"https:\/\/wpcalc.com\/en\/finance\/debt-consolidation\/\">Debt Consolidation Payment Calculator<\/a> can help you examine the proposed payment separately.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Estimate credit card interest for a billing cycle. Enter your APR and cycle length, then provide either your average daily balance or a starting balance and transactions.<\/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":[5],"tags":[25],"class_list":["post-67168","post","type-post","status-publish","format-standard","hentry","category-finance","tag-interest"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/67168","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=67168"}],"version-history":[{"count":1,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/67168\/revisions"}],"predecessor-version":[{"id":67205,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/67168\/revisions\/67205"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=67168"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=67168"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=67168"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}