Estimate your Monzo Flex monthly payments, interest, and total repayment cost for pay-in-full, 3-month, 6-month, 12-month, and 24-month plans.

Independent calculator

Monzo Flex Calculator

Representative APR default: 29%

Purchase amount

£

Repayment plan

Pay in full0% interest3 months0% if eligible6 monthsuses APR12 monthsuses APR24 monthsuses APR

APR for interest-bearing plans

%

Monzo says your actual Flex rate is personalised and shown in the app before you borrow.

3 months

£83.33

estimated monthly payment

Total interest

£0.00

Total repayable

£250.00

APR used

0%

Payments

3

Estimate only. This is not financial advice and it is not affiliated with Monzo.

Check Flex with Monzo

Compare repayment plans

Pay in full£250.00£0.00 interest3 months£83.33£0.00 interest6 months£45.26£21.57 interest12 months£24.25£40.99 interest24 months£13.85£82.40 interest

Use this Monzo Flex calculator to estimate the monthly payment, interest, and total cost before you choose a repayment plan. Enter the purchase amount, pick a term, and adjust the APR if Monzo shows you a personalised rate in the app.

Monzo currently lists Flex Purchase at 29% APR representative variable for interest-bearing borrowing, with 0% interest if you pay in full or pay in 3 months for purchases of £100 or more. Your actual rate can be different, so this calculator lets you edit the APR rather than hiding that assumption.

Why this calculator exists

I built this after buying something and not being sure whether Flexing it was worth it. The useful bit is not just the monthly payment; it is seeing how much extra the longer plans add compared with paying in full or using the 3-month option.

How accurate is it?

The calculator uses a standard fixed-payment APR estimate across the number of monthly payments. It is close enough for comparing plans, but it cannot know your personal Monzo offer, exact billing date, overpayments, missed payments, refunds, or any promotional add-ons.

This is independent, not financial advice, and not affiliated with Monzo. Always check the final repayment plan and rate inside the Monzo app before borrowing.

Quick notes

• Paying in full is treated as 0% interest.
• Paying in 3 months is treated as 0% when the purchase is £100 or more.
• 6, 12, and 24-month plans use the APR field.
• If Monzo shows you a different APR, type that into the calculator.

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Last updated on Jun 3, 2026