What is the Loan Calculator?
The Loan Calculator works out the fixed monthly payment on any instalment loan — personal, auto, student or business — from the loan amount, interest rate (APR) and term. Enter the three numbers and it returns your monthly payment, total interest paid over the life of the loan, total amount repaid, and a full month-by-month amortization schedule showing exactly how much of each payment goes to principal versus interest. This covers any loan with a fixed rate and a fixed number of equal payments — the same standard amortization math a bank uses internally, shown in full rather than hidden behind a single number.
Every fixed-rate instalment loan front-loads interest: early payments are mostly interest, later payments are mostly principal, even though the payment amount itself never changes. The chart and schedule this calculator produces make that visible directly, which is useful for understanding why paying off a loan early saves more in the first half of its term than the second.
Why use a free loan calculator?
The real amortization formula, not an approximation
Uses the standard fixed-payment formula banks and lenders use internally, so the monthly payment shown matches what an actual loan offer would quote at the same rate and term.
Full month-by-month schedule
See the principal, interest and remaining balance for every single payment across the entire term, not just the summary totals.
Total interest shown up front
The total interest figure makes the real cost of borrowing visible immediately — often a surprisingly large share of the total repaid, especially on longer terms.
Works for any fixed-rate instalment loan
Personal loans, auto loans, student loans, business term loans — anything with a fixed rate and a fixed number of equal payments uses the same math.
Handles 0% APR correctly
At exactly 0% interest the formula would divide by zero — this calculator switches to the correct simple division (loan amount ÷ number of payments) instead of breaking.
How do you use the Loan Calculator?
- 1
Enter the loan amount
The total amount you're borrowing, before any interest — this is the principal.
- 2
Enter the interest rate
The annual percentage rate (APR) quoted by the lender. This should be the APR, not a monthly rate.
- 3
Enter the loan term
How long you'll be repaying, in years. The calculator converts this to a number of monthly payments automatically.
- 4
Read the payment and open the full schedule
Your monthly payment, total interest and total repaid appear immediately. Expand the amortization schedule to see every individual payment broken down.
How is loan calculator calculated?
M = P × [r(1+r)ⁿ] ÷ [(1+r)ⁿ − 1]Where:
- M
- Monthly payment — the fixed amount you pay every month
- P
- Principal — the loan amount borrowed
- r
- Monthly interest rate — the annual rate (APR) divided by 100, then divided by 12
- n
- Total number of monthly payments — the loan term in years multiplied by 12
The simple version
Take the loan amount, apply the monthly interest rate compounded over every remaining payment, and spread the result evenly across all the payments so each one is identical in size. Early payments are mostly interest because the full balance is still outstanding; later payments are mostly principal because most of the balance has already been paid down — the total of each payment never changes, but what it's made of shifts every month.
What does it look like in practice?
A typical personal loan
Input
$25,000 at 7.5% APR over 5 years (60 payments)
Result
Monthly payment ≈ $501 · Total interest ≈ $5,058 · Total repaid ≈ $30,058
The monthly rate is 7.5% ÷ 12 = 0.625%. Over 60 payments, roughly 17% of every dollar repaid goes to interest at this rate and term.
Shortening the term
Input
Same $25,000 at 7.5% APR, but over 3 years (36 payments) instead of 5
Result
Monthly payment rises to roughly $778, but total interest drops to about $3,010
A shorter term always means a higher monthly payment and lower total interest — the tradeoff is fixed by the math, not a lender policy.
0% APR loan
Input
$6,000 at 0% APR over 24 months
Result
Monthly payment = $250 exactly · Total interest = $0
At 0% the standard formula divides by zero, so the calculator falls back to simple division: loan amount ÷ number of payments.
How accurate is it?
The monthly payment, total interest and schedule are computed with the exact standard amortization formula, run to full floating-point precision — not rounded intermediate steps. This is the same calculation method used by lenders to generate a loan offer, so the numbers should match an actual lender quote at the same rate and term closely.
- This calculates a fixed-rate, fixed-term loan with equal payments — it does not model variable-rate loans, where the rate (and therefore payment) can change during the term.
- Real loans often add origination fees, application fees or other charges that increase the effective cost beyond the APR modelled here — check your loan's full fee schedule, not just its headline rate.
- The final payment in the schedule is adjusted down slightly if needed so the balance reaches exactly zero, avoiding the small rounding overshoot that a naive calculation can produce.
- This is an estimate for planning purposes. Your actual lender-quoted payment may differ slightly due to day-count conventions, payment timing, or how a specific lender rounds intermediate values.
What should you know before using it?
How loan term and rate trade off against each other, holding the loan amount fixed:
| Change | Effect on monthly payment (see note for total interest) |
|---|---|
| Longer term | Lower — spread over more paymentsHigher — more time for interest to accrue on the outstanding balance |
| Shorter term | Higher — fewer payments to spread the total acrossLower — less time for interest to accrue |
| Higher interest rate | Higher, at any termHigher, at any term |
| Extra payments toward principal | Unchanged, unless you re-amortizeLower — see the Mortgage Calculator for a version of this tool with extra-payment modelling built in |
Which tools relate to the loan calculator?
The loan calculator is one of 21 calculators on this site. These are the ones most often used alongside it — either because they handle the next step in the same job, or because they answer a question this tool raises.
Mortgage Calculator
Uses the same core amortization formula, extended with property tax, insurance, HOA dues and extra-payment modelling for the specific case of a home loan.
GPA Calculator
If a student loan is part of your financial planning, check how your GPA affects scholarship or interest-rate eligibility on some loan programs.
Gas Mileage Calculator
For an auto loan, run the total cost of ownership alongside your fuel efficiency to see the full monthly cost of a vehicle, not just the payment.
When should you use a loan calculator?
Because the loan calculator runs entirely in your browser, it suits work you would not want to hand to a third-party server — client files, unpublished drafts, anything under an NDA. These are the situations people reach for it in most often.
Comparing loan offers
Run the same amount through different rate and term combinations to see the real monthly payment and total cost difference between competing offers.
Auto and personal loan planning
Check what monthly payment a given loan amount and term will actually produce before applying, rather than working backward from a lender's advertised rate alone.
Deciding between a shorter and longer term
See the exact tradeoff between a higher monthly payment now and lower total interest over the loan's life, in real numbers rather than a rule of thumb.
Student and business loan estimates
Model a fixed-rate student or business term loan the same way, using the loan's quoted APR and term.
Frequently asked questions
How do you calculate a monthly loan payment?
Why is most of my early payment interest instead of principal?
What is APR and how is it different from the interest rate?
Does paying extra reduce my monthly payment or shorten my loan?
Can I use this for a variable-rate loan?
Why does a 0% APR loan still show a monthly payment?
Is the loan calculator safe to use?
This tool runs entirely inside your browser. Your text, files and settings are processed on your own device and are never uploaded to our servers — there is nothing for us to store, log or leak. You can confirm it yourself: open your browser DevTools, switch to the Network tab, and use the tool. You will not see an upload request. It also means the tool keeps working if your connection drops mid-task.
Where do these figures come from?
Every method, threshold and standard this page relies on, with a link to the document that defines it. Check them — a tool that will not show its sources is asking you to take its word for it.
- 1Regulation Z (Truth in Lending), Appendix J to Part 1026 — Annual Percentage Rate Computations for Closed-End Credit Transactions
Consumer Financial Protection Bureau · 2011
Supports: The standard fixed-payment amortization formula (M = P × [r(1+r)ⁿ] ÷ [(1+r)ⁿ − 1]) used to calculate the monthly payment.
- 2What's the difference between a mortgage interest rate and an APR?
Consumer Financial Protection Bureau
Supports: The distinction drawn in the FAQ between the quoted interest rate and APR as the rate input to the formula.
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