Introduction
This Payment Plan Calculator shows you what you will pay each week, fortnight, month, or quarter to pay off a balance. Enter the total amount, any down payment, the yearly interest rate, and how many installments you want. The calculator gives you the payment amount, the total interest, and the total you will repay.
You can also flip it around. If you know how much you can pay each period, switch to "Calculate Installments" and the tool tells you how many payments you need to clear the debt.
Every result comes with a full amortization schedule. You can see how much of each payment goes to principal and how much goes to interest, plus your balance after each payment. Add a first payment date and the schedule shows real due dates. You can download the schedule as a CSV file, copy it, or print it.
Want to compare two plans? Turn on the comparison plan to see a short plan next to a long one. The calculator lists the difference in payment size, total interest, and plan length, so you can pick the plan that fits your budget. It also shows the step-by-step math and an interest-rate table, so you can see what happens if the rate moves up or down by one percent.
How to use our Payment Plan Calculator
Enter the amount you owe, any money you pay upfront, your interest rate, and how often you pay. The Payment Plan Calculator then shows your payment per period, the total interest, the total repaid, and a full amortization schedule.
Solve for: Pick "Calculate Payment" if you know how many payments you want to make. Pick "Calculate Installments" if you know the payment amount you can afford and want to know how many payments it takes.
Add comparison plan: Turn this on to set up a second plan (Plan B) and compare it with Plan A side by side. Leave it off if you only need one plan.
Total Amount: Type the full price or balance you owe before any down payment.
Down Payment: Type the money you pay upfront. Leave it blank or enter 0 if you pay nothing upfront. It must be less than the total amount.
Annual Interest Rate (%): Type the yearly interest rate for the plan. Enter 0 for an interest-free plan.
Payment Frequency: Choose how often you pay: weekly, fortnightly, monthly, or quarterly.
Number of Installments: In "Calculate Payment" mode, type how many payments you want to make. Use a whole number, up to 1,200.
Target Payment Amount: In "Calculate Installments" mode, type the amount you can pay each period. It must be big enough to cover the interest.
First Payment Date (optional): Pick the date of your first payment to add due dates to the schedule. Leave it blank to see period numbers only.
Click Calculate to see your results, or Reset to Defaults to start over. You can download the schedule as a CSV, copy it, or print it.
What Is a Payment Plan?
A payment plan lets you pay for something in small parts instead of all at once. You agree to pay a set amount each week, fortnight, month, or quarter until the balance reaches zero. Stores, dentists, schools, car dealers, and tax offices all use payment plans.
The Parts of a Payment Plan
- Total amount: the full price or balance you owe.
- Down payment: money you pay upfront. It lowers the amount you finance.
- Amount financed: the total minus the down payment. This is what interest is charged on.
- Interest rate: the yearly cost of borrowing, shown as a percent. Some plans are 0%.
- Payment frequency: how often you pay: weekly, fortnightly, monthly, or quarterly.
- Installments: how many payments you make in total.
How Each Payment Is Split
If your plan charges interest, every payment is split two ways. Part covers the interest that built up since your last payment. The rest pays down the balance, which is called principal. Early on, more of your money goes to interest. As the balance drops, more goes to principal. This slow shift is called amortization, and the list of every payment is an amortization schedule.
Short Plans vs. Long Plans
More installments means a smaller payment each time, but you owe the balance for longer, so you pay more interest in total. Fewer installments means bigger payments but less interest. There is no "best" answer. It depends on what you can afford each period without missing a payment.
The Math Behind It
The period rate is the yearly rate divided by the number of payments per year. For a monthly plan at 6%, that is 0.5% per month. The payment comes from the standard loan formula:
PMT = P × r × (1 + r)n ÷ [(1 + r)n − 1]
Here P is the amount financed, r is the rate per period, and n is the number of installments. At 0% interest, the math is simple: just divide the amount financed by the number of payments.
Effective Annual Rate (EAR)
Interest that is charged each period also earns interest on itself. The EAR shows the true yearly cost once that compounding is counted. It is always equal to or higher than the plain yearly rate. Weekly plans compound more often, so their EAR is slightly higher than a monthly plan at the same stated rate.
Things to Check Before You Sign
- Total repaid: not just the payment size. Compare the full cost of each option.
- Fees: setup fees, late fees, and admin fees can cost more than the interest.
- 0% offers: read the fine print. Some add back all the interest if you miss one payment.
- Extra payments: paying more than required cuts the balance faster and saves interest.
- Final payment: it is often a few cents different, since rounding leaves a small amount to clear.
A Simple Example
You owe $12,000 and pay $2,000 down, so $10,000 is financed at 6% per year over 12 monthly installments. The monthly rate is 0.5%. Your payment works out near $860.66, you pay about $327.90 in interest, and the total repaid, including the down payment, is roughly $12,327.90. Stretch the same debt to 24 months and the payment drops to about $443, but interest more than doubles.