Loan Repayment Calculator
Enter a loan's principal, annual interest rate and term to get the monthly payment, total interest, and a full reducing-balance amortization schedule — the same method Ustawi's Lending app uses to schedule repayments.
| Month | Payment | Principal | Interest | Balance |
|---|---|---|---|---|
| 1 | 183,360 | 153,360 | 30,000 | 1,846,640 |
| 2 | 183,360 | 155,660 | 27,700 | 1,690,980 |
| 3 | 183,360 | 157,995 | 25,365 | 1,532,984 |
| 4 | 183,360 | 160,365 | 22,995 | 1,372,619 |
| 5 | 183,360 | 162,771 | 20,589 | 1,209,848 |
| 6 | 183,360 | 165,212 | 18,148 | 1,044,636 |
| Reducing balance | Flat rate | |
|---|---|---|
| Monthly payment | 183,360 | 196,667 |
| Total interest | 200,320 | 360,000 |
| Total repayment | 2,200,320 | 2,360,000 |
At the same headline rate, flat interest costs TZS 159,680 more. Compare the two methods →
How this is calculated
This calculator uses the reducing-balance method. Interest each month is charged only on the balance still outstanding, so as you repay the principal the interest portion of each payment shrinks and more of your money goes to clearing the loan. The monthly payment itself stays level for the whole term.
Show the calculation formula
Monthly Payment = P × [r(1+r)^n] / [(1+r)^n − 1]
where P is the principal, r is the monthly rate (annual rate ÷ 12), and n is the number of months. Each month, interest is charged on the outstanding balance, the rest of the payment reduces the principal, and the balance shrinks toward zero.
What is an amortization schedule?
It is the row-by-row plan of every payment across the loan’s life, showing how much of each installment is interest versus principal and what balance remains. Because interest is charged on a falling balance, the interest share is largest at the start and smallest at the end.
Reducing balance vs flat rate
This calculator uses reducing balance. A flat-rate loan charges interest on the original principal for the whole term, so the same headline rate costs the borrower considerably more. To see exactly how much more, use the Flat vs Reducing-Balance Comparison.
FAQ
How is the monthly payment worked out?
It uses the standard reducing-balance (annuity) formula: M = P × [r(1+r)^n] / [(1+r)^n − 1], where r is the monthly rate (annual rate ÷ 12) and n is the number of months. Interest each month is charged only on the balance still outstanding.
What is an amortization schedule?
A month-by-month breakdown of every payment split into the interest portion and the principal portion, plus the remaining balance. Early payments are mostly interest; later payments are mostly principal.
Does this use flat-rate or reducing-balance interest?
Reducing balance — interest is charged on the shrinking outstanding balance, not the original principal. Flat-rate loans cost more; use the Flat vs Reducing-Balance Comparison to see the difference.
Why does the last payment differ slightly?
The final installment absorbs rounding so the balance ends at exactly zero rather than a few shillings off — this mirrors how a real loan ledger closes out.
Does it handle a 0% interest loan?
Yes — at 0% the payment is simply the principal divided by the number of months, with no division-by-zero error.
Is anything I enter saved or sent anywhere?
No. The whole calculation runs in your browser; nothing you type leaves your device.
Manage your lending with Ustawi.
This schedule is the same reducing-balance method Ustawi uses to run real loans. From applications and approval to disbursement, repayments, collections and portfolio reporting, financial institutions run their whole lending operation on one platform.
