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Loan calculator
Work out your monthly loan payment from the amount, APR and term — plus total interest, total paid, the payoff date, and what $100 extra a month saves you.
★ MONEY · LOAN CALCULATOR · MONTHLY PAYMENT
Loan Calculator: Monthly Payment & Total Interest 2026
Monthly payment $500.95 — a $25,000.00 loan at 7.5% over 5 years costs $5,056.92 in interest. The total paid is $30,056.92, and the last payment is October 2031. Add $100.00 a month and the loan ends in 49 months and saves $1,013.66.
One formula turns a loan into a monthly payment
A $25,000.00 loan at 7.5% APR over 5 years costs $500.95 a month — 60 payments of $500.95 add up to $30,056.92, of which $5,056.92 is interest and $25,000.00 is the loan itself. The first payment is November 2026 and the last is October 2031. On the defaults — $25,000.00 loan, 7.5% APR, 5 years, $0.00 extra — the monthly payment is $500.95, the total paid is $30,056.92 and the total interest is $5,056.92.
| Scenario | Loan | Payment | Total interest | Total paid | Payoff | Extra payment |
|---|---|---|---|---|---|---|
| Default ($25,000, 7.5%, 5 yr) | $25,000.00 | $500.95 | $5,056.92 | $30,056.92 | October 2031 | — |
| Amount $40,000 | $40,000.00 | $801.52 | $8,091.08 | $48,091.08 | October 2031 | — |
| APR 10% | $25,000.00 | $531.18 | $6,870.57 | $31,870.57 | October 2031 | — |
| Amount $15,000 | $15,000.00 | $300.57 | $3,034.15 | $18,034.15 | October 2031 | — |
| 3-year term | $25,000.00 | $777.66 | $2,995.60 | $27,995.60 | October 2029 | — |
| 7-year term | $25,000.00 | $383.46 | $7,210.38 | $32,210.38 | October 2033 | — |
| Extra $100/mo | $25,000.00 | $500.95 | $5,056.92 | $30,056.92 | October 2031 | 49 months, interest $4,043.26, saved $1,013.66 |
Check the identities: monthly rate = APR ÷ 12; payments = years × 12; payment = P·r(1+r)^n / ((1+r)^n − 1); total paid = payment × payments; total interest = total paid − loan. At the defaults the payment is $500.95, the total paid is $30,056.92 and the total interest is $5,056.92. Rounding convention: totals are computed from unrounded values, so rounded parts may differ by a cent from their rounded sum.
The worked example, line by line
Setup: $25,000.00 loan, 7.5% APR, 5 years, $0.00 extra.
Line 1 — the monthly rate. 7.5% ÷ 12 = 0.625% a month, or 0.00625 as a decimal.
Line 2 — the payments. 5 years × 12 = 60 payments.
Line 3 — the formula. M = $25,000.00 × 0.00625 × (1.00625)^60 / ((1.00625)^60 − 1) = $500.95 a month.
Line 4 — the totals. $500.95 × 60 = $30,056.92 paid in total, minus the $25,000.00 loan = $5,056.92 of interest. The first payment is November 2026 and the last is October 2031.
Reverse: the loan amount for a $500/mo payment is $24,952.65 (exact $24,952.6541); the forward is $500.00/mo. The APR for a $450/mo payment is 3.07% (exact 3.0704%); at 3.07% the payment is $450.00, at the exact 3.0704% it is $450.00. The shortest whole-year term whose monthly payment stays under $600 is 5 years (payment $500.95); at 4 years it is $604.47 — payments fall as the term lengthens. The extra payment to pay the loan off in 3 years is $276.71/mo — the smallest cent value achieving 36 months (the bisection threshold is $276.705); with the rounded extra the loan ends in 36 months with total interest $2,995.58 and interest saved $2,061.34; one cent less, $276.70/mo, gives 37 months with total interest $2,995.62 and interest saved $2,061.30. The loan amount for a $750/mo payment is $37,428.98 (exact $37,428.9811); the forward is $750.00/mo. The loan amount for a $1,000/mo payment is $49,905.31 (exact $49,905.3082); the forward is $1,000.00/mo.
Every branch, checked
Amount $40,000: Payment $801.52/mo, total interest $8,091.08, total paid $48,091.08, payoff October 2031 (60 payments). A bigger loan costs more every month and much more in total — the interest alone is $8,091.08.
APR 10%: Payment $531.18/mo, total interest $6,870.57, total paid $31,870.57, payoff October 2031 (60 payments). Two and a half extra points of rate lift the payment to $531.18 and the total interest to $6,870.57 — $1,813.64 more interest than at 7.5%.
Amount $15,000: Payment $300.57/mo, total interest $3,034.15, total paid $18,034.15, payoff October 2031 (60 payments). A smaller loan is cheaper in every way — the payment is $300.57 and the interest is $3,034.15.
3-year term: Payment $777.66/mo, total interest $2,995.60, total paid $27,995.60, payoff October 2029 (36 payments). The payment rises to $777.66, but the total interest falls to $2,995.60 — and the payoff moves to October 2029.
7-year term: Payment $383.46/mo, total interest $7,210.38, total paid $32,210.38, payoff October 2033 (84 payments). The payment falls to $383.46, but the total interest rises to $7,210.38 — stretching the loan costs $2,153.46 more interest.
Extra $100/mo: Payment $500.95/mo, total interest $5,056.92, total paid $30,056.92, payoff October 2031 (60 payments); with $100.00 extra: 49 months, interest $4,043.26, saved $1,013.66 (11 months saved), total paid $29,043.26, payoff November 2030. The loan ends in 49 months (November 2030), 11 months early, and the total interest falls to $4,043.26 — saving $1,013.66.
What the defaults assume
The model assumes principal & interest ONLY — the payment assumes a fixed rate and equal monthly payments for the whole term, and taxes, insurance, fees and any origination charge are NOT included, so the real monthly bill is higher. It assumes the first payment month is the month after the loan starts. It assumes the extra-payment simulation pays the extra toward principal every month, with each month’s interest rounded to cents, and that the loan is paid off in the month the remaining balance, rounded to cents, reaches $0.00 — a sub-cent residual is a rounding artifact, not a real extra month. With no extra payment the simulation totals $5,056.96 of interest — $0.04 more than the unrounded $5,056.92 — because each month’s interest is rounded to cents; the saved figure only becomes meaningful once you add an extra payment. At 0% APR the payment is $416.67 — $25,000.00 ÷ 60, no interest at all. Over 1 year the payment is $2,168.94 and the total interest is $1,027.23. A $0 loan has a payment of $0.00 — model-level, there is no loan to pay, and the calculator still returns $0.00 rather than an error. With $500/mo extra the loan ends in 28 months with total interest $2,266.93 — saving $2,789.99. Rounding convention: totals are computed from unrounded values, so rounded parts may differ by a cent from their rounded sum; the reverses are nearest-value solutions, and the exact unrounded figures ($24,952.6541, 3.0704%, $276.7050, $37,428.9811, $49,905.3082) are stated wherever the rounded figures appear.
Output · formula · meaning
| Output | Formula | What it means |
|---|---|---|
| Loan amount | the amount you borrow | $25,000.00. |
| Monthly payment | P·r(1+r)^n / ((1+r)^n − 1) | $500.95. |
| Total paid | monthly payment × number of payments | $30,056.92. |
| Total interest | total paid − loan | $5,056.92. |
| Payoff date | first payment November 2026 + n − 1 months | October 2031 (60 payments). |
| Months with extra payment | month-by-month simulation | 60. |
| Total interest with extra payment | simulated month by month | $5,056.96. |
| Interest saved with extra payment | default total interest − simulated total interest | -$0.04. |
| Loan for a $500/mo payment | P × (f−1)/(r×f) | $24,952.65 → $24,952.65. |
| APR for a $450/mo payment | bisection on the payment | 3.0704% → 3.07%. |
| Shortest term under $600/mo | the shortest whole-year term whose payment stays under $600 | 5 years. |
| Extra payment to pay off in 3 years | the smallest cent value achieving 36 months | $276.71/mo → $276.71/mo. |
| Loan for a $750/mo payment | P × (f−1)/(r×f) | $37,428.98 → $37,428.98. |
| Loan for a $1,000/mo payment | P × (f−1)/(r×f) | $49,905.31 → $49,905.31. |
| Amount $40,000 | same model | Payment $801.52/mo, total interest $8,091.08, total paid $48,091.08, payoff October 2031 (60 payments). |
| APR 10% | same model | Payment $531.18/mo, total interest $6,870.57, total paid $31,870.57, payoff October 2031 (60 payments). |
| Amount $15,000 | same model | Payment $300.57/mo, total interest $3,034.15, total paid $18,034.15, payoff October 2031 (60 payments). |
| 3-year term | same model | Payment $777.66/mo, total interest $2,995.60, total paid $27,995.60, payoff October 2029 (36 payments). |
| 7-year term | same model | Payment $383.46/mo, total interest $7,210.38, total paid $32,210.38, payoff October 2033 (84 payments). |
| Extra $100/mo | same model | Payment $500.95/mo, total interest $5,056.92, total paid $30,056.92, payoff October 2031 (60 payments); with $100.00 extra: 49 months, interest $4,043.26, saved $1,013.66 (11 months saved), total paid $29,043.26, payoff November 2030. |
Who uses this
- The car buyer borrowing $25,000: they learn the payment is $500.95 a month — and they check the 3-year branch ($777.66) to see what a shorter loan costs.
- The borrower with a $500 monthly budget: they learn they can borrow $24,952.65 — and they check the $750 reverse ($37,428.98) to see what a bigger budget buys.
- The borrower with $100 a month to spare: they learn it ends the loan in 49 months (November 2030) — and they check the $276.71 reverse (36 months) to see what a 3-year payoff takes.
- The borrower choosing between a 5- and a 7-year loan: they learn the 7-year payment is $383.46 but costs $2,153.46 more interest — and they check the 3-year branch ($2,995.60) for the cheap end.
Accuracy & limitations
The math is first-principles amortization: payment = P·r(1+r)^n / ((1+r)^n − 1); total paid = payment × n; total interest = total paid − loan; the extra-payment simulation runs month by month with each month’s interest rounded to cents and stops when the remaining balance, rounded to cents, reaches $0.00. The 4-decimal exact is shown where the rounding matters: the APR for a $450/mo payment is 3.0704% (shown as 3.07%); the extra payment for a 3-year payoff is $276.7050/mo at the bisection threshold (shown as $276.71/mo — the smallest cent value that achieves 36 months); the loan for a $500/mo payment is $24,952.6541 (shown as $24,952.65). What the model cannot do is price YOUR loan: it is principal & interest only — taxes, insurance, fees and any origination charge are not included, the rate is assumed fixed for the whole term, and real lenders round each monthly payment to cents, which shifts the final payment by a few cents. For the mortgage version, see the mortgage payment calculator; for paying a loan off early, see the loan payoff calculator; for the extra-payment plan in detail, see the extra loan payment calculator; and for paying a loan off early, see early loan payoff. This is a calculator, not financial advice.
Cite this calculatorBright Side Kit. “Loan Calculator: Monthly Payment & Total Interest 2026” brightoolbox.com, 2026. Method: monthly rate r = APR/100/12; number of payments n = years × 12; monthly payment M = P·r(1+r)^n / ((1+r)^n − 1); total paid = M × n (from the unrounded M); total interest = total paid − loan; payoff date: first payment November 2026, last payment = first payment + n − 1 months; extra-payment simulation month by month (the monthly payment is the ROUNDED payment plus the extra; monthly interest = balance × r, rounded to cents; the last payment is capped at the amount due; the loan is paid off in the month the remaining balance, rounded to cents, reaches $0.00 — a sub-cent residual is a rounding artifact, not a real extra month); interest saved = default total interest − simulated total interest (unrounded-derived; may differ by a cent from the rounded parts). Principal & interest ONLY — the payment assumes a fixed rate and equal monthly payments for the whole term; taxes, insurance, fees and any origination charge are NOT included; the first payment month is the month after the loan starts. Defaults: $25,000 loan, 7.5% APR, 5 years, $0 extra → monthly payment $500.95, total paid $30,056.92, total interest $5,056.92, payoff October 2031 (60 payments). Branches: Amount $40,000 → Payment $801.52/mo, total interest $8,091.08, total paid $48,091.08, payoff October 2031 (60 payments); APR 10% → Payment $531.18/mo, total interest $6,870.57, total paid $31,870.57, payoff October 2031 (60 payments); Amount $15,000 → Payment $300.57/mo, total interest $3,034.15, total paid $18,034.15, payoff October 2031 (60 payments); 3-year term → Payment $777.66/mo, total interest $2,995.60, total paid $27,995.60, payoff October 2029 (36 payments); 7-year term → Payment $383.46/mo, total interest $7,210.38, total paid $32,210.38, payoff October 2033 (84 payments); Extra $100/mo → Payment $500.95/mo, total interest $5,056.92, total paid $30,056.92, payoff October 2031 (60 payments); with $100.00 extra: 49 months, interest $4,043.26, saved $1,013.66 (11 months saved), total paid $29,043.26, payoff November 2030. Reverses: loan for a $500/mo payment = $24,952.65 (exact $24,952.6541; forward $500.00/mo); APR for a $450/mo payment = 3.07% (exact 3.0704%; at 3.07% the payment is $450.00, at the exact 3.0704% it is $450.00); shortest whole-year term whose payment stays under $600 = 5 years (payment $500.95; at 4 years it is $604.47 — payments fall as the term lengthens); extra payment to pay off in 3 years = $276.71/mo (smallest cent value achieving 36 months; bisection threshold $276.7050; with the rounded extra the loan ends in 36 months with total interest $2,995.58 and interest saved $2,061.34; one cent less, $276.70/mo, gives 37 months with total interest $2,995.62 and interest saved $2,061.30); loan for a $750/mo payment = $37,428.98 (exact $37,428.9811; forward $750.00/mo); loan for a $1,000/mo payment = $49,905.31 (exact $49,905.3082; forward $1,000.00/mo). Edges: 0% APR → Payment $416.67/mo, total interest $0.00, total paid $25,000.00, payoff October 2031 (60 payments); 1-year term → Payment $2,168.94/mo, total interest $1,027.23, total paid $26,027.23, payoff October 2027 (12 payments); $0 loan → Payment $0.00/mo, total interest $0.00, total paid $0.00, payoff October 2031 (60 payments); $500/mo extra → Payment $500.95/mo, total interest $5,056.92, total paid $30,056.92, payoff October 2031 (60 payments); with $500.00 extra: 28 months, interest $2,266.93, saved $2,789.99 (32 months saved), total paid $27,266.93, payoff February 2029.
Bright Side Kit. "Loan Calculator: Monthly Payment & Total Interest 2026" https://brightoolbox.com/loan-calculator/ Accessed October 25, 2026.Frequently asked questions
How much is the monthly payment on a $25,000 loan?
$500.95. A $25,000.00 loan at 7.5% APR over 5 years costs $500.95 a month. The total paid is $30,056.92 and the total interest is $5,056.92.
How much can I borrow with a $500 monthly payment?
$24,952.65. A $500/mo payment supports a $24,952.65 loan at 7.5% over 5 years (exact $24,952.6541); the forward is $500.00/mo.
What APR gives a $450 monthly payment on a $25,000 loan?
3.07%. The APR for a $450/mo payment on a $25,000.00 loan over 5 years is 3.07% (exact 3.0704%). At the displayed 3.07% the payment is $450.00; at the exact 3.0704% it is $450.00.
What is the shortest loan term with a payment under $600?
5 years. The shortest whole-year term whose monthly payment stays under $600 is 5 years (payment $500.95). At 4 years the payment is $604.47 — above $600.
How much extra a month pays a $25,000 loan off in 3 years?
$276.71/mo. The extra payment to pay the loan off in 3 years instead of 5 is $276.71/mo — the smallest cent value achieving 36 months (the bisection threshold is $276.705). With the rounded extra the loan ends in 36 months with total interest $2,995.58 and interest saved $2,061.34. One cent less, $276.70/mo, gives 37 months.
How much can I borrow with a $750 monthly payment?
$37,428.98. A $750/mo payment supports a $37,428.98 loan at 7.5% over 5 years (exact $37,428.9811); the forward is $750.00/mo. A $1,000/mo payment supports $49,905.31.
What is the payment on a $25,000 loan at 0% APR?
$416.67. At 0% APR the payment is $416.67 — $25,000.00 ÷ 60, no interest at all.
How much does $100 extra a month save?
$1,013.66. Adding $100.00 a month ends the loan in 49 months (November 2030), 11 months early, and saves $1,013.66 of interest.