Payment Calculator
Calculate the fixed monthly payment for any loan based on amount, rate, and term.
Payment Calculator
Calculate your monthly payment instantly.
Monthly Payment
$0What a Payment Calculator Is For
Most borrowing decisions start from the wrong end. You're shown a price, then told what the monthly cost will be. This tool lets you start from the number you actually control — what you can afford each month — and work backwards to everything else.
A loan has four moving parts: the amount borrowed, the interest rate, the repayment period, and the payment itself. Fix any three and the fourth is fixed too. That's the whole idea here — decide which three you're confident about, and let the calculation reveal the one you're unsure of.
Two Ways to Use It
Fixed Term
You know the amount, the rate, and how long you want to take. The result is the monthly payment. Use this when the repayment period is already set — a 5-year car loan, a 3-year personal loan.
Fixed Payment
You know the amount, the rate, and what you can realistically pay each month. The result is how long clearing the debt will take. Use this when your budget is the hard constraint.
The second approach is the one most people skip, and it's often more revealing. Committing to $400 a month feels straightforward until you see whether that means three years of payments or nine.
The Formulas
Both directions use the same amortisation relationship, rearranged to solve for whichever value is missing.
Solving for the Payment
PMT = P × r / [ 1 − (1+r)−n ]
PMT = Monthly Payment · P = Loan Amount · r = Monthly Interest Rate · n = Number of Months
Solving for the Term
n = −log(1 − P×r / PMT) / log(1+r)
n = Number of Months · P = Loan Amount · r = Monthly Interest Rate · PMT = Monthly Payment
The second formula carries a built-in warning. If your chosen payment is smaller than the monthly interest charge, the expression inside the logarithm turns negative and no answer exists — because the balance would grow rather than shrink. That threshold is worth knowing before you commit to any minimum payment.
Worked Example: Starting From a Budget
Say you owe $20,000 at 11% and want to know what different monthly commitments actually buy you:
| Monthly payment | Time to clear | Total interest | Total paid |
|---|---|---|---|
| $300 | ≈ 7 yrs 5 mo | ≈ $6,590 | ≈ $26,590 |
| $400 | ≈ 5 yrs 1 mo | ≈ $4,340 | ≈ $24,340 |
| $500 | ≈ 3 yrs 10 mo | ≈ $3,270 | ≈ $23,270 |
| $650 | ≈ 2 yrs 10 mo | ≈ $2,340 | ≈ $22,340 |
Raising the payment from $300 to $500 costs $200 more each month but saves $3,320 and cuts three and a half years off the term. The jump from $500 to $650 saves far less — diminishing returns set in quickly once the term is already short.
The biggest savings come from the first increase above the minimum, not from stretching to the absolute maximum you could pay. Find the point where the extra dollar stops buying much, and keep the difference as a cushion.
Why Minimum Payments Cost So Much
Every payment is split before anything reduces your balance. Interest accrued that month is taken first; whatever is left over goes to principal. When the payment barely exceeds the interest charge, almost nothing comes off the debt.
On that same $20,000 at 11%, the first month's interest is roughly $183. A $200 payment leaves $17 toward principal — the balance falls by less than a tenth of a percent, and clearing it that way would take decades. A $400 payment leaves $217, more than twelve times as much progress for double the money.
This non-linearity is why two people with identical debts can end up paying wildly different totals. The payment size relative to the interest charge matters far more than the size of the debt itself.
Setting a Payment You Can Actually Sustain
The highest payment you can theoretically manage and the highest you should commit to are different numbers. Lenders assess the first; you have to live with the second.
- Work from take-home pay, not gross. Tax and deductions have already gone; the calculation only makes sense against what lands in your account.
- Count every existing commitment. Rent, other loans, card minimums, insurance. The new payment sits on top of all of it.
- Keep total debt payments under 40% of take-home pay. Under 30% if you're also paying rent or a mortgage.
- Leave a genuine buffer. Committing to your absolute maximum means any unexpected cost turns into a missed payment.
- Test a bad month. If your income dropped 20% for three months, could the payment still be made? If not, it's set too high.
What the Result Doesn't Include
The figure above covers principal and interest — the core of any loan payment. Depending on what you're borrowing for, the real monthly cost may be higher.
| Loan type | Commonly added on top |
|---|---|
| Mortgage | Property tax, home insurance, PMI, HOA dues |
| Auto loan | Vehicle insurance, registration, maintenance |
| Personal loan | Origination or processing fees, optional payment protection |
| Student loan | Capitalised interest accrued during study or deferment |
Ask any lender for the APR rather than the headline rate. APR folds mandatory fees into a single figure, which makes two offers genuinely comparable.
Practical Ways to Bring the Payment Down
- Increase the deposit. A smaller principal reduces the payment directly, and removes the interest that principal would have accrued.
- Shop the rate, not the payment. Sellers compete on monthly figures because a longer term hides a worse deal. Compare APR across at least three lenders.
- Improve your credit before applying. Clearing revolving balances and correcting file errors a few months ahead can move you into a cheaper tier.
- Refinance if rates have fallen. A lower rate on the remaining balance reduces the payment without extending the term.
- Be wary of extending an existing loan. Refinancing to a longer term lowers the payment but usually raises the total cost. Run both figures before agreeing.
- Reconsider the purchase price. The cleanest way to lower a payment is to borrow less in the first place.
Frequently Asked Questions
Start with the payment if your budget is the binding constraint — it tells you honestly how long the commitment will last. Start with the term if the repayment period is already fixed by the loan type. Running it both ways takes a few seconds and usually changes what you decide.
Because interest is taken out first. Once that month's interest is covered, every additional dollar goes straight to principal — and each dollar removed from the balance stops accruing interest for the whole remaining term. The effect compounds, which is why modest increases produce disproportionate savings.
Because the payment you entered doesn't cover the monthly interest charge. The balance would grow rather than shrink, so no repayment period exists. Raise the payment above the interest amount and the calculation will resolve.
No. A lower payment usually means a longer term and substantially more interest overall. It's the right choice when monthly cash flow is genuinely tight, but it should be a deliberate decision rather than the default the seller steers you toward.
A widely used guideline keeps all debt payments combined under 40% of take-home pay, dropping to around 30% if rent or a mortgage is included in that total. Lenders may approve more, but approval reflects their risk tolerance, not your comfort.
That depends on the lender, and it's worth asking explicitly. Applying extra to principal while keeping the payment fixed shortens the term and saves the most interest. Some lenders instead recalculate the payment downward, which frees cash flow but saves less.
It works as a close approximation if you stop adding new charges and pay a fixed amount monthly. Card interest is typically calculated daily on the average balance rather than monthly on a fixed one, so treat the result as a solid estimate rather than an exact schedule.
The maths is exact for the terms you enter. Real agreements often add origination fees, insurance requirements, or charges rolled into the balance, so use this to compare scenarios and rely on the lender's written offer for final numbers.