Loan Repayment Calculator

What Is Loan Repayment?

Every installment on an amortizing loan is split two ways before it does anything else. The lender first takes the interest that has accrued since the last payment; whatever remains of the installment reduces the debt. The Consumer Financial Protection Bureau states it plainly: "In an amortizing loan, a percentage of your monthly payment is applied to the principal and to the interest."

Interest and Principal: the Two Halves of a Payment

The interest half is charged on what you currently owe, not on what you originally borrowed. One twelfth of the annual rate is applied to the balance standing at the start of that month. On 25,000 borrowed at 7.5%, the monthly rate is 0.625%, so the first month's interest is 156.25 — and since the installment is 500.95, the other 344.70 comes off the debt, leaving 24,655.30.

The following month the interest is charged on 24,655.30 rather than on 25,000, so it falls to 154.10 and the principal share rises to 346.85. The installment itself has not moved; only its composition has. That is what "reducing balance" means, and it is why the cost of a loan cannot be found by multiplying the amount borrowed by the rate by the number of years. That shortcut assumes you owe the full amount for the entire term, which you never do: on this loan it gives 25,000 × 7.5% × 5 = 9,375, against a true interest bill of 5,056.92.

When Interest Really Does Dominate the Early Payments

The familiar claim — that early payments are mostly interest — is a mortgage fact rather than a universal one. The CFPB's own wording is careful: "At the beginning of your loan term, more of your payment is generally applied toward the interest rather than the principal." Whether it holds on your loan depends on the rate and the length of the term together, because a long term makes the installment small relative to the balance it is charged against.

• At 7.5%, interest exceeds principal in the very first payment only once the term passes 112 months — a little over nine years.
• At 6.5% that tipping point sits at 129 months; at 10% it drops to 84 months; at 5% it rises to 167 months.
• On the 25,000 five-year loan above, the principal share leads from payment one — 344.70 against 156.25 — and its lead widens every month after that.

On long loans the effect is severe. A 300,000 mortgage at 6.5% over 30 years carries an installment of 1,896.20. The principal share does not overtake the interest share until payment 233 of 360, and the balance does not fall below half until payment 257 — twenty-one years and five months in. Five years of those payments send 94,605.18 to interest while the balance falls only to 280,832.93, a reduction of 19,167.07 on a 300,000 debt.

What This Calculator Returns

Three figures come out, from three numbers and a unit switch going in. The installment, the sum of every installment, and the gap between that sum and the amount borrowed.

• Monthly EMI — the fixed installment, identical every month for the whole term.
• Total Payment — that installment multiplied by the number of months.
• Total Interest — the total payment minus the amount borrowed.

What it does not return is a schedule. There is no month-by-month table in the panel, no field for an extra payment, and no payoff date. The month-by-month figures further down this page were worked out by hand from the same formula so that the three headline numbers can be traced back to something you can check.

The EMI page runs this same arithmetic and adds a fourth output line naming the term in months, and it accepts amounts below 1,000, which this tool refuses. For a small loan, or when the term in months is the number you want confirmed, use the EMI Calculator.

How Do You Calculate Loan Repayment?

One formula produces the installment, and two subtractions produce everything else. It is the standard monthly amortization payment — the same arithmetic behind a car loan, a personal loan and a mortgage. Only the numbers fed into it change.

The Loan Repayment Formula

EMI = P × i × (1 + i)^n ÷ ((1 + i)^n − 1)

P = the amount borrowed
i = annual rate ÷ 12 ÷ 100      (the monthly rate, as a decimal)
n = the term in months

Total Payment  = EMI × n
Total Interest = Total Payment − P

• i is monthly and decimal. A rate of 7.5% becomes 7.5 ÷ 12 ÷ 100 = 0.00625 — not 7.5, and not 0.075.
• n counts payments, not years. A term entered in years is multiplied by twelve before anything else happens, so five years and 60 months are the same input.
• Only the first line is a calculation. Total payment and total interest are bookkeeping that falls out of it, which is why the total interest cannot be found without first finding the installment.

The awkward-looking (1 + i)^n term is a compounding factor: it is what one unit of debt at the start of the loan would grow to by the end if nothing were repaid. Dividing by that factor minus one is what forces the balance to land exactly on zero at payment n rather than stopping short or overshooting.

Step by Step

Any calculator with a power key will do this in about a minute.

• Divide the annual rate by 12, then by 100. That is i.
• If the term is in years, multiply it by 12. That is n.
• Raise (1 + i) to the power of n, keeping every decimal the display will give you.
• Multiply that result by P and by i — that is the numerator.
• Subtract 1 from the power term — that is the denominator.
• Divide the numerator by the denominator. The answer is the monthly installment.
• Multiply the installment by n for the total, then subtract P from the total for the interest.

Step three is where hand arithmetic drifts. Rounding (1 + i)^n to four decimals on a thirty-year loan shifts the installment by more than a cent, and that error is then multiplied by 360. The calculator carries full double precision all the way through and rounds once, at the point of display.

Worked Example: 25,000 at 7.5% Over 60 Months

Loan Amount 25000, Annual Interest Rate 7.5, Tenure Unit set to Months, Loan Tenure 60.

i = 7.5 ÷ 12 ÷ 100 = 0.00625
n = 60
(1.00625)^60 = 1.45329441

EMI = 25,000 × 0.00625 × 1.45329441 ÷ (1.45329441 − 1)
    = 227.077251 ÷ 0.45329441
    = 500.94871…

Monthly installment

500.95

Sixty of those installments come to 30,056.92, of which 5,056.92 is interest. That is 16.8% of everything handed over, and 20.2% added on top of the amount borrowed. Setting the unit to Years and entering 5 returns the same three figures, because the years-to-months conversion happens before the formula runs.

Where the Money Goes, Month by Month

The panel prints three numbers rather than a schedule, but the schedule follows directly from them. Interest for any month is that month's opening balance times 0.00625, and the rest of the 500.95 comes off the balance. Repeat sixty times and the same loan looks like this:

Halfway in time is not halfway in money. The balance first drops below 12,500 at payment 33 of 60, and by that point 77.9% of the loan's total interest has already been charged. Settling or refinancing at the midpoint therefore costs more than the calendar suggests — the interest is front-loaded even on a loan whose principal share led from the very first payment.

The two middle columns are mirror images of each other. Because the installment never changes, every cent the interest falls by is a cent the principal rises by — 156.25 and 344.70 in the first month, 3.11 and 497.84 in the last, both pairs adding to 500.95. Nothing about the loan changed along the way; that is simply what charging a fixed rate on a shrinking balance looks like.

Loan Repayment Chart: What Term and Rate Cost

Two levers move these numbers, and they do not move them the same way. Lengthening the term buys a large cut in the monthly figure at a very large cost in interest. Changing the rate pushes both in the same direction, and more gently than most people expect.

What the Term Costs: 100,000 at 10%

Same amount, same rate, six terms. Each row is what the panel returns when only the tenure changes.

From five years to twenty, the installment falls by 1,159.68 a month — 54.6% lower — while the interest multiplies by nearly 4.8. Somewhere between the fifteen-year and twenty-year rows the interest bill passes the amount borrowed: at 10% the crossing point is a term of 191 months, fifteen years and eleven months.

Past twenty years the trade collapses. Another full decade takes just 87.45 off the monthly figure while adding roughly 84,300 to the interest, and the thirty-year row pays out 215,925.77 in interest alone — more than twice the sum borrowed. Each extra year of term buys less relief than the year before it and costs more, which is why the useful question is never "what is the longest term available" but "what is the shortest one I can service".

What the Rate Costs: 25,000 Over 60 Months

Now hold the amount and the term where they are and move only the rate.

Across the ordinary range one percentage point costs almost exactly the same, wherever you add it: 7% to 8% raises the installment by 11.88 and the interest by 712.79 over the five years. So for a 25,000 five-year loan the working rule is about 12 a month and about 700 in total per point. Because the installment is directly proportional to the amount borrowed, the same point on 50,000 costs exactly twice as much.

The rule loosens at the bottom of the table. Between 18% and 24% the interest climbs from 13,090.14 to 18,151.95 — those six points cost about 840 each, against about 710 a point down in single digits. A percentage point is worth more the higher the rate it is added to, so shopping the rate pays off most on the loans where the rate is already worst.

Choosing a Term You Can Carry

Both charts argue for the shortest term, and that argument holds only up to the point where the installment stops being payable. A missed payment brings late fees and a mark on your credit file, neither of which appears anywhere in these tables, so the term to aim for is the shortest one whose monthly figure still survives a bad month.

Test the trade rather than guessing at it. On 25,000 at 7.5%, cutting the term from 60 months to 48 raises the installment by 103.52 and drops the interest from 5,056.92 to 4,014.68 — a saving of 1,042.24. Cutting it to 36 months takes the installment to 777.66 and the interest to 2,995.60. Run all three and choose against your actual budget, not against the chart.

How to Read Your Result

The panel stays on a dash until you press Calculate. All three number fields open empty, and the calculator only runs itself when the page loads if every field already carries a value, so nothing is computed until you fill the boxes and submit. It does not recalculate as you type.

The Three Lines the Panel Returns

For 25,000 at 7.5% over 60 months the panel reads, exactly:

• Monthly EMI: 500.95 — the headline readout. The label sits inside the large figure rather than above it.
• Total Payment on the left, 30056.92 on the right — the installment times 60, calculated before rounding.
• Total Interest on the left, 5056.92 on the right — the total payment minus the 25,000 borrowed.

There are always three segments, never more and never fewer. The two breakdown rows split at the colon into a label and a value; the headline keeps its label inside the readout. Figures print to two decimals with no thousands separators and no currency symbol at all. Nothing here converts currency, so whatever unit you type in is the unit that comes back out — the tables on this page add separators for legibility, the panel does not.

A copy button below the panel lifts the headline and both breakdown rows as plain text, which is the fastest way to line two offers up somewhere you can see them together. Reset clears the form and returns the panel to its dash.

Entering the Term in Years or in Months

Tenure Unit is a two-button control that opens on Years. It does not convert the answer; it converts the input. Choose Years and the number you type is multiplied by twelve before the formula sees it, so 5 becomes 60 payments.

The two routes agree exactly. 25,000 at 7.5% entered as 5 years and the same loan entered as 60 months both return Monthly EMI: 500.95. The switch earns its place on terms that are quoted in months — a 78-month offer, say, which the Years box can only reach as 6.5. Fractions are accepted: 0.5 in the Years box is read as six months and returns Monthly EMI: 4258.29 on that loan.

When the Panel Refuses

Two different guards can stop a calculation, and they produce different messages. A blank field is caught before the formula runs; an impossible value is caught by the formula itself.

• Blank fields are named. Leave the amount empty and the amber notice reads: Enter a value for Loan Amount. Leave the rate empty as well and it names both: Enter a value for: Loan Amount, Annual Interest Rate. Whichever fields are empty are the ones listed.
• Filled but impossible values reach the formula and come back as the single phrase Invalid input, under the heading Check your inputs. Three things trigger it: an amount below 1,000, a rate of zero or less, and a tenure of zero or less.
• Tenure Unit can never be blank, because it is a pair of buttons with Years selected from the start.

The 1,000 floor is the one that catches people out, and it applies to the amount alone. An amount of 999 is refused outright, while 1,000 at 10% over one year is accepted and returns Monthly EMI: 87.92, a total payment of 1054.99 and total interest of 54.99. A rate of zero is refused too, which means a genuine 0% promotional offer cannot be modeled here at all — for that loan, divide the amount by the number of months, which is exactly what a 0% schedule does.

Rounding, and the Final Payment

Every figure is computed at full precision and rounded once, at the moment it is printed. The installment on the 25,000 loan is really 500.94871…, and the total payment line is built from that number rather than from the displayed 500.95.

So the two do not quite reconcile: sixty payments of 500.95 come to 30057.00, while the panel prints 30056.92. Eight cents across five years is nothing, but the principle holds at every scale. Any total you build by multiplying a displayed installment by the number of months is accurate to about a payment, not to the cent, and the same caution applies to differences — subtracting two printed figures can land a cent away from the difference computed before rounding.

A real lender's schedule absorbs this by adjusting the final installment to clear whatever is genuinely left, so the last payment is usually a few cents different from the other fifty-nine. Nothing here models that. Every month in this calculation is the same figure, and the balance is assumed to land precisely on zero.

Limits: When This Calculator Does Not Apply

The arithmetic is exact for one specific product: a fixed-rate loan repaid in equal monthly installments, with interest accruing on the reducing balance and nothing else attached to it. Each item below is a case where that description stops fitting, and the figure on screen starts answering a different question.

No Schedule, No Prepayments, No Fees

Three things this page discusses that the tool itself does not compute. There is no amortization table in the panel. There is no field for an extra payment, so the effect of overpaying has to be approximated by re-running the loan with a shorter term. And there is no fee input, so origination charges, documentation fees and insurance premiums are simply absent from every figure.

That approximation is close but not identical. A real overpayment shortens the term while leaving the installment where it was; re-running with a shorter term raises the installment to fit. It tells you the direction of the saving and roughly its size, not the exact number your lender would quote.

For repayment on a quarterly, half-yearly or annual cycle, and for a down payment taken off the amount before any interest is charged, the more general version of this tool is the Loan Calculator.

The Rate Is a Nominal Rate, Not an APR

What goes in the rate box is a nominal annual rate, divided by twelve to produce the monthly rate. That is not the same thing as the APR a lender advertises. The CFPB defines the interest rate as "the cost you will pay each year to borrow the money, expressed as a percentage rate", and describes the APR as "a broader measure of the cost of borrowing money than the interest rate" — one that "reflects the interest rate, any points, mortgage broker fees, and other charges that you pay to get the loan".

Type an APR into the rate box and the installment comes out higher than the one you will actually be billed, because the APR already has the fees folded into the rate and this formula then charges that inflated rate against the full amount for the full term. Type the note rate instead and the installment is right, but the total cost line understates what the loan costs you, since the fees never appear. Neither figure is wrong. They answer different questions, and it is worth knowing which one you asked.

The Field Limits Are Advisory

The rate box declares a minimum of 0.1 and a maximum of 50, and the tenure box a minimum of 1. The form is submitted without browser validation, so those figures guide the spinner arrows and nothing more.

• A rate of 60 submits and computes: on 25,000 over 60 months it returns Monthly EMI: 1320.70, well past the field's stated ceiling of 50.
• A rate of 0.05 also computes, returning Monthly EMI: 417.20 on the same loan.
• A tenure of 0.5 in the Years box computes as six months rather than being rejected.
• The only limit that genuinely holds is the 1,000 floor on the amount, and it is enforced by the formula rather than by the field.

This matters most for the rate, because nothing catches a misplaced decimal point. A rate typed as 750 instead of 7.5 produces a confident, cleanly formatted and completely useless answer. Check the rate before you trust the installment.

Structures This Does Not Represent

In each of these the figure on screen is not slightly off. It is modeling something else.

• Variable and adjustable rates. The installment holds only for as long as the rate does, and nothing here reprices it.
• Flat-rate or precomputed interest, where the finance charge is fixed at signing and calculated on the original amount rather than on a falling balance. The true cost is higher than reducing-balance math predicts for the same headline rate.
• Interest-only periods, balloon payments and deferred-start loans, none of which repay the balance evenly to zero.
• Escrowed housing costs. Property tax and insurance are collected alongside a mortgage installment but are not part of it; the figure here is principal and interest only.
• Weekly, fortnightly and quarterly schedules. Everything in this calculation is monthly.
• Prepayment penalties. The CFPB describes one as "a fee that some lenders charge if you pay off all or part of your mortgage early", typically applying only within the first three or five years — a charge that can eat part of the saving from clearing a loan ahead of schedule.

Housing needs the version that carries property tax, insurance, HOA fees and a down payment alongside principal and interest, because those are collected with the installment but priced entirely separately from it — that is the Mortgage Calculator.