Free Loan Calculator Online

A loan calculator answers one question immediately: given a loan amount, an annual interest rate, and a repayment term, what will the fixed monthly payment actually be, and how much of the total cost ends up being interest rather than principal? Enter a principal, a rate, and a term in years, and this loan calculator returns the monthly payment, the total interest paid across every scheduled payment, and the total amount that leaves your account by the time the loan is retired, recalculating the instant any number changes. It handles any fixed-rate, fully amortizing loan — a personal loan, an auto loan, a debt-consolidation loan, a business term loan — using the same standard amortization formula lenders use internally to quote a payment, not a rough approximation.

How the Calculator Works

Three fields drive the calculation, each with a paired slider for quick adjustment: the loan amount (a dollar input plus a slider running from $1,000 to $1,000,000), the annual interest rate (a percentage input plus a slider from 0.1% to 25%), and the loan term in years (an input plus a slider from 1 to 40 years). A fourth, optional field lets you add an extra fixed amount to every monthly payment — useful for testing what happens if you pay more than the required minimum.

• Summary view. The default results tab shows the monthly payment as a large headline figure (including any extra payment you've added), followed by total interest and total amount paid over the full term. A donut chart breaks the total cost into its principal and interest shares, with the exact percentage of each labeled next to it, and the number of months to payoff sits at the chart's center.
• Amortization view. A second tab switches to a yearly-summarized table — one row per year showing that year's principal paid, interest paid, cumulative interest to date, and remaining balance — so you can see the balance trajectory without scrolling through hundreds of individual monthly rows.
• Extra payment impact. When the extra payment field holds a nonzero value, the calculator shows a callout stating exactly how many months of payments that extra amount eliminates, comparing the accelerated payoff timeline against the original term.

Everything updates live — there's no calculate button to press and no page reload between adjustments, so testing five different interest-rate scenarios back to back takes five slider drags rather than five separate form submissions.

The core calculation is also available as a metered API endpoint, documented at /docs: send a principal, an annual rate, and a term in years as JSON, and it returns the monthly payment, total interest, and total paid as numbers — for example, a $200,000 loan at 6% over 30 years returns a monthly payment of $1,199.10, total interest of $231,676.38, and a total paid of $431,676.38. The API covers the base fixed-rate calculation only; the extra-payment acceleration and the yearly amortization breakdown shown in the browser tool are calculator-side features, not part of the current API response, so a backend integration that needs the accelerated-payoff math would need to run the extra-payment scenario as a second request with a shorter effective term or handle that logic on its own end.

Why This Calculator Earns Its Place

The monthly payment figure a lender quotes is rarely the whole story, and working it out independently ahead of a conversation with a lender changes the leverage in that conversation:

• Comparing offers from multiple lenders. Two lenders quoting different rates and terms for the same loan amount produce genuinely different total costs, and running both through the same calculator with the same principal makes the comparison apples-to-apples rather than trusting each lender's own disclosure format.
• Budgeting for a car or personal loan before applying. Knowing the monthly payment at a realistic rate before walking into a dealership or filling out an application prevents a shock during the paperwork stage, when the pressure to sign is highest.
• Testing how term length changes total cost. Stretching the same loan from a 3-year term to a 5-year term lowers the monthly payment but raises total interest substantially — seeing both numbers side by side, rather than just the smaller monthly figure, is the whole point of running the comparison before committing.
• Evaluating whether extra payments are worth it. Adding $100 a month toward a loan sounds like a small change; the calculator's payoff-months callout shows the actual time saved, which is often large enough to change the decision.
• Sanity-checking a debt-consolidation plan. Rolling several debts into a single new loan only makes sense if the new fixed payment and total interest actually beat what the separate debts would have cost, and that comparison requires running the consolidated loan's real numbers rather than trusting a lender's marketing framing.

Technical Deep Dive: The Amortization Formula Behind the Payment

The monthly payment on a fixed-rate loan comes from a single formula: M = P × [r(1+r)^n] / [(1+r)^n − 1], where P is the principal, r is the monthly interest rate (the annual rate divided by 12, expressed as a decimal), and n is the total number of monthly payments (years × 12). This is the same formula banks and lenders use internally — there's no proprietary or simplified version at play, and any calculator claiming to do this differently is either rounding somewhere it shouldn't or working from a different set of assumptions about how interest accrues.

What the formula doesn't make obvious at a glance is how the payment splits between principal and interest changes over the loan's life. Every month, interest is charged on the current outstanding balance — early on, when the balance is close to the original principal, most of the fixed payment goes toward interest, and only a small slice reduces the balance. Shrink the balance and you shrink the interest charged against it too, which leaves a bigger portion of that unchanging payment free to knock down principal instead. This is why the calculator's amortization table shows the balance dropping slowly at first and increasingly fast in the loan's later years, even though the payment itself never changes.

A rounding note worth being explicit about: the monthly payment the calculator displays is computed to full floating-point precision and only rounded for display, and the final month of a real amortization schedule typically has a payment that's a few cents different from every other month, to zero out the balance exactly rather than leaving a fractional-cent residue. That's standard practice, not a calculation error, and it's the same behavior a bank's own amortization schedule shows.

An honest comparison of the common ways people work out a loan payment:

Method	Uses the actual amortization formula	Shows total interest	Speed
Rough mental estimate ("rate × years" guesswork)	No — systematically inaccurate	No	Instant but unreliable
A lender's pre-approval quote	Yes, but tied to that lender's specific offer	Sometimes, buried in fine print	Requires an application or soft inquiry
Spreadsheet with a PMT formula	Yes, if set up correctly	Only if built in separately	Moderate — setup time each use
Dedicated loan calculator	Yes, built in	Yes, shown directly	Fast, no setup

Comparing Ways to Estimate a Payment

A few alternatives people reach for, and where each one holds up or falls short:

• Asking the lender directly. Accurate for that lender's specific offer, but comparing three lenders means three separate conversations or applications, and some soft-inquiry quotes carry their own friction.
• A financial calculator app or physical calculator. Handles the amortization formula correctly if you know how to enter the variables, but most don't show the split between principal and interest at a glance or track how extra payments shorten the term.
• A spreadsheet template. Reliable once built and genuinely useful for comparing many scenarios at once, but building a correct PMT-based amortization table from scratch is more setup than a single payment check calls for.
• A browser-based loan calculator. Built specifically for this one job — enter three or four numbers, see the payment, the total cost, and the payoff timeline immediately, with no formula to remember or spreadsheet to maintain.

How Your Loan Numbers Are Handled

Every figure entered into this loan calculator — principal, rate, term, and any extra payment — is calculated entirely inside your browser using JavaScript. Nothing you type is sent to a server or stored anywhere, and there's no account or sign-in step involved. Refreshing or closing the tab clears the numbers instantly, and every visitor gets the identical calculation with no usage cap.

Common Questions About Loan Payments

Does making an extra payment every month actually shorten the loan term, or just reduce the last payment?

It shortens the term. Because interest is charged only on the outstanding balance, an extra amount applied on top of the required payment reduces that balance faster than scheduled, which means less interest accrues going forward and the loan reaches a zero balance in fewer total months — the calculator's payoff-months figure reflects this directly rather than just spreading the extra amount across the original term.

Why is the total interest so much higher on a long-term loan even at a similar rate?

Interest accrues on whatever balance remains, for as many months as the balance remains outstanding. A longer term means more months of interest charges on a slowly shrinking balance, even if the rate itself is identical or lower than a shorter-term alternative — which is why total interest, not just the monthly payment, is worth comparing before choosing a term.

Can this calculator be used for an auto loan or is it only for mortgages or personal loans?

It works for any fixed-rate, fully amortizing loan regardless of what it's financing — a car, a personal expense, business equipment, or a debt-consolidation loan all use the identical payment formula. A home purchase with property tax and insurance folded into the monthly payment is the one case with extra moving parts, which is what the dedicated mortgage calculator on this site handles separately.

Does the monthly payment shown include fees like origination charges?

No. The calculator works from the loan principal, rate, and term alone — it doesn't add origination fees, closing costs, or other charges a lender might roll into the loan or collect upfront, since those vary by lender and loan type. If a lender quotes an origination fee, add it to the principal you enter here to see its effect on the monthly payment, or keep it separate to see the base payment on its own.

Why does the monthly payment stay exactly the same every month if the interest portion keeps changing?

That's the defining feature of a fixed-rate amortizing loan — the total payment is calculated once, up front, to be constant for the entire term, while the internal split between principal and interest shifts month to month as the balance changes. A loan where the payment itself changes over time, like some adjustable-rate or interest-only structures, follows different math than the standard amortization formula this calculator uses.

How accurate is this compared to what my actual lender will offer?

The math itself matches standard lender formulas exactly for the rate and term you enter — the gap between this calculator's output and your eventual offer comes entirely from the rate a specific lender approves you for, which depends on credit history, income verification, and underwriting factors this tool has no access to and doesn't attempt to estimate.

Related Tools

For a home purchase specifically, where property tax, insurance, and a down payment all factor into the real monthly cost, the Mortgage Calculator extends this same amortization math with those extra pieces built in. To see the full period-by-period breakdown behind any fixed-rate loan — every single payment's principal, interest, and remaining balance, not just a yearly summary — the Amortization Schedule Calculator generates the complete table. If you're comparing how a lump sum grows under compounding rather than how a loan gets paid down, the Compound Interest Calculator covers that side of the math. Cross-border purchases involving tax-inclusive pricing are a job for the VAT Calculator, and anyone converting a quoted salary into a take-home figure before deciding what loan payment actually fits their budget can start with the Salary Converter.