{"id":67173,"date":"2026-10-20T09:51:47","date_gmt":"2026-10-20T06:51:47","guid":{"rendered":"https:\/\/wpcalc.com\/en\/?p=67173"},"modified":"2026-10-20T09:51:47","modified_gmt":"2026-10-20T06:51:47","slug":"simple-interest-calculator","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/finance\/simple-interest-calculator\/","title":{"rendered":"Simple 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\">Calculate Simple Interest or Solve for a Missing Value<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"67173\" data-favorite-title=\"Simple Interest\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/finance\/simple-interest-calculator\/\" data-favorite-excerpt=\"Calculate simple interest or solve for a missing principal, annual rate, or time. Choose what to solve for, then enter the other values and a time unit.\" 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\/simple-interest-calculator\/\" method=\"POST\" class=\"calculator\" id=\"calculator-67173\" data-post=\"67173\"><fieldset class=\"fieldset-input is-2\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field is-single\" id=\"input-1\"><label for=\"field-1\">Solve for<\/label><div class=\"grid grid-cols-1\"><select id=\"field-1\" name=\"solve_for\"><option value=\"interest\" selected>Interest<\/option><option value=\"principal\">Principal<\/option><option value=\"rate\">Annual interest rate<\/option><option value=\"time\">Time<\/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\">Principal (P)<\/label><input type=\"text\" name=\"principal_p\" id=\"field-2\" aria-describedby=\"calc-unit-2\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"0\" value=\"1000\"\/><div class=\"unit\" id=\"calc-unit-2\">$<\/div><\/div><div class=\"field\" id=\"input-3\"><label for=\"field-3\">Annual interest rate (r)<\/label><input type=\"text\" name=\"annual_interest_rate_r\" id=\"field-3\" aria-describedby=\"calc-unit-3\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"0\" max=\"100\" value=\"6\"\/><div class=\"unit\" id=\"calc-unit-3\">%<\/div><\/div><div class=\"field\" id=\"input-4\"><label for=\"field-4\">Time (t)<\/label><input type=\"text\" name=\"time_t\" id=\"field-4\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"0\" value=\"3\"\/><\/div><div class=\"field\" id=\"input-5\"><label for=\"field-5\">Time unit<\/label><div class=\"grid grid-cols-1\"><select id=\"field-5\" name=\"time_unit\"><option value=\"years\" selected>Years<\/option><option value=\"months\">Months<\/option><option value=\"days\">Days<\/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-6\" hidden><label for=\"field-6\">Day-count basis<\/label><div class=\"grid grid-cols-1\"><select id=\"field-6\" name=\"daycount_basis\"><option value=\"360\">360 days per year<\/option><option value=\"365\" selected>365 days per year<\/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-7\" hidden><label for=\"field-7\">Interest (I)<\/label><input type=\"text\" name=\"interest_i\" id=\"field-7\" aria-describedby=\"calc-unit-7\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"0\" value=\"180\"\/><div class=\"unit\" id=\"calc-unit-7\">$<\/div><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"67173\">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> Interest and Balance Growth<\/h3><div class=\"result-box\"><div class=\"field-result is-column\" id=\"output-1\"><span class=\"field-title\"><span>Solved value<\/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\" id=\"output-2\"><span class=\"field-title\"><span>Simple interest (I)<\/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>Total amount (A = P + I)<\/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>Amount with annual compounding<\/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 class=\"field-result is-column\" id=\"output-5\"><span class=\"field-title\"><span>Compound interest comparison<\/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>Year-by-year balance growth<\/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=\"67173\" 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>Simple 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}I &amp;= P r t \\\\ A &amp;= P + I \\\\ P &amp;= \\frac{I}{rt} \\\\ r &amp;= \\frac{I}{Pt} \\\\ t &amp;= \\frac{I}{Pr}\\end{aligned}\\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(I\\) \u2014 simple interest earned or charged ($)<\/li>\n<li>\\(P\\) \u2014 principal, or starting amount ($)<\/li>\n<li>\\(r\\) \u2014 annual interest rate expressed as a decimal<\/li>\n<li>\\(t\\) \u2014 time in years<\/li>\n<li>\\(A\\) \u2014 total amount, including principal and interest ($)<\/li>\n<\/ul>\n<p>Simple interest is calculated only on the original principal, so it grows at a constant rate over time. The calculator rearranges the same formula when you choose to solve for principal, rate, or time.<\/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>Simple Interest \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> A $1,000 principal earns 6% simple interest per year for 3 years. Find the interest and total amount.<\/p>\n<p>\\[I = 1{,}000(0.06)(3) = \\$180.00\\]<\/p>\n<p>\\[A = 1{,}000 + 180 = \\$1{,}180.00\\]<\/p>\n<p>For comparison, the calculator\u2019s annually compounded amount is \\(1{,}000(1.06)^3 = \\$1{,}191.02\\), or $11.02 more.<\/p>\n<p><strong>Result:<\/strong> $180.00 in simple interest and a total amount of $1,180.00.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to use the calculator<\/h2>\n<ol>\n<li>In <strong>Solve for<\/strong>, select <strong>Interest<\/strong>, <strong>Principal<\/strong>, <strong>Annual interest rate<\/strong>, or <strong>Time<\/strong>. The field for the value being solved is hidden; enter the other three values.<\/li>\n<li>Enter <strong>Principal (P)<\/strong> in dollars and <strong>Annual interest rate (r)<\/strong> as a percentage where those fields are shown. For example, enter 6 for 6%, not 0.06.<\/li>\n<li>Set <strong>Time unit<\/strong> to <strong>Years<\/strong>, <strong>Months<\/strong>, or <strong>Days<\/strong>. Enter the duration in <strong>Time (t)<\/strong> if you are not solving for time. If you select Days, also choose a <strong>Day-count basis<\/strong> of 365 or 360 days per year.<\/li>\n<li>When solving for principal, rate, or time, enter the target dollar amount in <strong>Interest (I)<\/strong>. Read the answer under <strong>Solved value<\/strong>. When solving for interest, read <strong>Simple interest (I)<\/strong> instead.<\/li>\n<li>Check <strong>Total amount (A = P + I)<\/strong> for the principal plus simple interest. The results also show an annually compounded comparison and a year-by-year balance table.<\/li>\n<\/ol>\n<h2>What simple interest means<\/h2>\n<p>Simple interest is a charge or return calculated on the starting principal throughout the period. It does not add previously earned interest to the amount used for later interest calculations. At a 6% annual rate, a $1,000 principal earns $60 for each full year under this model. Over three years, that is $180 in interest, regardless of how the balance is displayed along the way.<\/p>\n<p>The annual rate and duration work together: doubling either one doubles simple interest if the other inputs stay the same. The rate is entered as a percentage but converted to a decimal for the formula; 6% becomes 0.06. Months are divided by 12 to obtain years. Days are divided by the selected 360- or 365-day basis, which can change the answer for the same number of days.<\/p>\n<p>The <strong>Year-by-year balance growth<\/strong> table begins at year zero, shows each complete elapsed year, and adds a final row for a partial year if needed. Its simple balance is the original principal plus accumulated simple interest. The <strong>Amount with annual compounding<\/strong> instead uses \\(P(1+r)^t\\): interest is effectively earned on earlier interest. For partial years, this comparison uses a fractional-year exponent. It is a comparison model, not necessarily the method a particular account or contract uses.<\/p>\n<h2>Assumptions and practical limits<\/h2>\n<p>This calculator assumes a constant annual rate, an unchanged principal, and no deposits, withdrawals, payments, fees, or taxes. The total amount is not a loan repayment schedule or a prediction of an investment\u2019s actual return. For an account that reinvests earnings, use the <a href=\"https:\/\/wpcalc.com\/en\/finance\/compound-interest\/\">Compound Interest Calculator<\/a>; for borrowing with scheduled payments, use the <a href=\"https:\/\/wpcalc.com\/en\/finance\/loan-calculator\/\">Loan Calculator<\/a>.<\/p>\n<p>Use the day-count basis specified by your agreement when entering days. The 360-day option treats 360 days as one year; the 365-day option treats 365 days as one year. Neither option automatically counts calendar years, leap days, or dates. If your agreement calculates interest differently, its result may not match this estimate. A product that deducts interest upfront may also need a different approach, such as the <a href=\"https:\/\/wpcalc.com\/en\/finance\/discounted-interest\/\">Discounted Interest Calculator<\/a>.<\/p>\n<p>Inputs must produce positive principal, rate, time, and interest. The calculator limits principal to $1 trillion, the annual rate to 100%, time to 100 years, and entered interest to $1 quadrillion. Dollar results are displayed to two decimal places, so small differences may be hidden by rounding.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Calculate simple interest or solve for a missing principal, annual rate, or time. Choose what to solve for, then enter the other values and a time unit.<\/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-67173","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\/67173","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=67173"}],"version-history":[{"count":1,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/67173\/revisions"}],"predecessor-version":[{"id":67200,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/67173\/revisions\/67200"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=67173"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=67173"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=67173"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}