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Rule of 78 Settlement Calculator

This calculator works out the settlement figure of any loan using the Rule of 78, with an adjustable deferment (default 2 months). It assumes all repayments are made on time.

⚠ For non-regulated agreements only (outside the Consumer Credit Act).
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Overview

The Rule of 78 calculator works out an early-settlement figure using the sum-of-digits method. It's meant for non-regulated agreements, the ones outside the Consumer Credit Act, where the actuarial method isn't required. Enter the loan amount, the term, the repayment amounts, how many months have run and a deferment period, and it returns the settlement figure, the interest rebate and the APR.

The Rule of 78 weights interest towards the early months of an agreement, so it rebates less interest on early settlement than the actuarial method does. The name comes from a one-year loan: the digits 1 to 12 add up to 78. If your agreement is a regulated consumer-credit agreement, use the actuarial settlement calculator instead. The Rule of 78 is only appropriate where the regulations don't apply.

How it works

01
Enter the agreement

Loan amount, term in months, the first, standard and final repayments, the number of months that have run, and the deferment period (two months by default).

02
We apportion the interest

Total interest is the sum of the repayments less the loan. The Rule of 78 spreads that interest across the months using sum-of-digits weighting.

03
Get the rebate and settlement

The interest for the months not yet elapsed is credited back as a rebate, and the settlement is the total repayable less what you have paid and the rebate.

Worked example

Settling a 12-month loan after 6 months

Take a £2,000 loan repaid at £180 a month over 12 months. That's £2,160 repayable, so £160 of interest. Settle it after 6 payments with no deferment, and under the Rule of 78 the rebate is based on the six remaining months: (6+5+4+3+2+1) ÷ (12+11+…+1) = 21 ÷ 78 of the interest, a rebate of about £43.08.

With £1,080 already paid, the settlement figure is £2,160 − £1,080 − £43.08 = £1,036.92. The rebate is noticeably less than a straight half of the interest, because the Rule of 78 treats more of it as earned in the early months.

Frequently asked questions

What is the Rule of 78?
A method of apportioning interest that weights it towards the early months of an agreement, using the sum of the months' digits. For a 12-month loan the digits 1 to 12 add up to 78, which gives the method its name. On early settlement it rebates the interest for the months not yet reached.
When should I use the Rule of 78 instead of the actuarial method?
Only for non-regulated agreements outside the Consumer Credit Act. UK regulated consumer-credit agreements must use the actuarial method, so use the settlement calculator for those.
Why does the Rule of 78 give a smaller rebate?
Because it front-loads the interest. More of it is treated as already earned in the early months, so less is rebated when you settle early compared with the actuarial method.
What is the deferment period?
An allowance of extra months (two by default) added before the rebate is calculated, which reduces the rebate slightly. You can adjust it to match the terms of the agreement.

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