Overdraft Interest Calculator
Work out how much an overdraft costs. Enter the amount overdrawn, the EAR and the number of days to see the interest charged.
Your overdraft
From your bank.
Your results
Interest charged
£13.99
About per day
£0.47
Total owed
£513.99
Assumes the same amount is overdrawn every day. Your bank applies interest to your actual daily balance.
How overdraft interest works
An overdraft lets you spend more than is in your account, for a price. Since April 2020 most UK banks quote a single annual interest rate (the EAR) rather than a mix of fees and charges, which makes comparing easier.
Overdrafts are meant for short-term use. Staying overdrawn for months can cost far more than other forms of borrowing.
Getting out of your overdraft
If you are regularly overdrawn, look at your budget and consider a lower-cost way to borrow. A free debt adviser can help you look at the options if it is getting out of hand.
How to use this calculator
- Enter the amount you are overdrawn and the overdraft rate (EAR) from your bank.
- Enter the number of days you expect to stay overdrawn.
- Read the interest and total owed.
How it is calculated
Interest = amount × ((1 + EAR)^(days ÷ 365) − 1). This treats the quoted rate as an effective annual rate.
Worked example
Being £500 overdrawn at 39.9% EAR for 30 days costs about £13.99 in interest, taking the total owed to £513.99.
Assumptions and limits
- The amount overdrawn stays the same for the whole period.
- Banks apply interest to your daily balance, so a changing balance will give a different result.
- Your bank’s rate, fees and any buffer may differ. Check your account terms.
Common questions
What is EAR?
The effective annual rate: the yearly cost of borrowing allowing for interest being added during the year.
Do I get interest-free days?
Some accounts have an interest-free buffer. This calculator assumes none, so enter only the days you are charged.
Is an unarranged overdraft more expensive?
It can be, and may risk charges or refused payments. Check your bank’s terms.
Why is my bank’s figure slightly different?
Banks calculate interest on a daily balance, which changes as money goes in and out.
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These calculators give estimates based on the figures you enter and the assumptions listed above. They are not financial advice. Your numbers are worked out in your browser and are not sent to us.
This page provides general information only. It is not personalised financial, legal or tax advice, and rules and figures can change. Your situation is unique — please check official sources such as GOV.UK and MoneyHelper, and speak to a qualified, FCA-authorised debt adviser before making important decisions about your money.