See the cost of paying a little more.

The result compares your chosen plan with additional monthly payments so you can see the possible time and interest savings.

If the payment does not exceed the interest being added, the calculator flags the plan instead of pretending the balance will fall.

UNDERSTANDING THE PAYOFF

The payment has to beat the interest being added.

Debt repayment becomes clearer when you look at the balance month by month. A payment first covers the interest generated by the balance; the remainder reduces principal. As the balance falls, the interest component can fall too, allowing more of a fixed payment to reduce the debt.

APR matters

A higher APR increases the interest charged for the same starting balance, which can make a low monthly payment much less effective.

Extra payments

A controlled extra amount can reduce the number of interest-bearing months. Compare the base plan with one realistic extra-payment scenario.

Do not ignore fees

Some borrowing products have charges or rules around early repayment. The calculator is a model and may not represent a product's contractual terms.

Worked example

On a £5,000 balance at 10% APR, the first month's simple interest is about £41.67 before the monthly payment is applied. A £200 payment therefore has roughly £158.33 available to reduce the principal in that first month, assuming the rate and timing model used here.

MoneyHelper advises borrowers to compare APR, total repayment, fees, penalties and the monthly cost when assessing borrowing. MoneyHelper: managing credit well →

REVIEWED SEPTEMBER 2026

Use the result as a plan, not a promise.

The displayed payoff date assumes the balance, rate and payment behaviour you entered continue. Real accounts can differ because interest may be calculated daily, rates can change, fees can be added and minimum payments can be revised.

When comparing debt scenarios, change one variable at a time. For example, keep the APR fixed and add £25 a month. The change in months and interest then shows the effect of that single decision more clearly.

The monthly payment is only half the story.

Two debt plans can have the same starting balance and still produce very different outcomes because of the APR, payment amount and time. A higher payment normally reduces the number of interest-bearing months. A lower payment can keep the balance outstanding for longer.

Interest first

In the model, monthly interest is calculated from the current balance before the payment reduces it. This reflects why a high APR can make a small payment feel like it is barely moving the debt.

Extra payments

An extra monthly amount is tested separately so you can see the possible change in payoff time and interest. The comparison is designed to make small payment changes visible.

Target time

Working backwards from a target number of months can help turn a vague goal into a required payment. If that payment does not fit the household budget, change the target rather than hiding the mismatch.

Example: a £5,000 balance at 20% APR is very different at £150 a month from £250 a month. The higher payment does not just reduce the monthly burden sooner; it also reduces the number of months over which interest is charged.

Keep the plan realistic and protect essential costs.

A debt calculation should sit inside a household budget. Before choosing a larger payment, make sure essential housing, utilities, food, transport and other commitments are covered. A plan that looks efficient on paper but causes missed essential bills is not a useful plan.

It is also worth distinguishing between different types of borrowing. The calculator uses a simple amortising model; actual credit products can have fees, promotional periods, minimum payments, variable rates or rules that are not represented here.

Compare the current plan with one controlled change

Try your existing payment first. Then increase it by a modest amount and compare the change in payoff time and interest. This shows the marginal effect of the extra payment without assuming a complete change in your finances.

Debt payoff calculator FAQs

What if my monthly payment is lower than the monthly interest?

The model flags the plan because the balance would not fall under those assumptions. Increasing the payment or checking the actual interest terms is necessary to understand what will happen.

Does this calculator know my lender's minimum payment?

No. Enter the payment you are considering. Product-specific minimums, fees and contract rules are outside this simple planning model.

Should I include an extra payment every month?

Only if it is realistic for your budget. The calculator is useful for testing whether a consistent extra amount changes the timeline enough to matter.

Can I use one APR for every debt?

Only as a scenario assumption. Different cards and loans can have different rates and fee structures, so separate calculations may be more informative.