Fee or interest: two different costs
A US overdraft is usually priced as a fee for each item the bank pays when your account is short, not as interest. Overdraft protection linked to a line of credit or another account is a different arrangement: you borrow from the line, and interest runs on the amount borrowed. This page prices both for the same overdrawn amount, so you can see how they differ. It does not know any bank's fees: enter the fee from your bank's fee schedule.
The fee is shown as a yearly rate by dividing the fee by the amount overdrawn and scaling to 365 days: fee ÷ amount × 365 ÷ days. The line of credit is charged simple daily interest at APR ÷ 365 on the amount drawn.
Worked example: $100 overdrawn for 5 days
A $30 fee for one item on a $100 overdraft that you repay after 5 days costs $30.00, which is 2190.00% as a yearly rate. The same $100 on a line of credit at 18% costs $0.25 in interest for the 5 days, or $0.05 a day. The $30 and 18% figures are examples, not any bank's terms.
More than one item, and a longer time
Three items at $35 on a $300 overdraft repaid after 10 days cost $105.00 in fees, equal to 1277.50% as a yearly rate. A $5,000 overdraft kept for a year at 15% on a line of credit costs $750.00 in interest, against $50.00 for two $25 fees. Fees dominate for short, small overdrafts; interest dominates for large balances held for months.
What this calculator leaves out
It does not include extended or continuing overdraft fees, monthly line-of-credit fees, transfer fees, or any limit on how many fees a bank charges in a day. It does not know whether your account has opted in to overdraft coverage for debit card and ATM transactions. Your bank's fee schedule and account agreement are the final word.
To compare a line of credit with a personal loan, use the line of credit vs loan calculator.
To price card borrowing instead, use the credit card interest calculator.
Use the right country page
This page uses dollars and US account terms. The country choices above the inputs open separate local pages. Choosing United Kingdom opens the UK overdraft loan interest calculator, which prices an overdraft from an effective annual rate in pounds. Inputs reset and amounts are not converted.
Inputs for the overdraft fee and interest calculator
Amount overdrawn
The total your account is overdrawn by until you repay it.
Days until you repay it
How many days the account stays overdrawn. A whole number from 1 to 365.
Overdraft items charged
How many payments the bank covers and charges a fee for. A whole number.
Fee per item
Your bank's overdraft fee for each item. Take it from its fee schedule.
Line of credit APR
The APR if an overdraft line of credit covers the amount instead.
CALCULATOR QUESTIONS
US overdraft fee and interest calculator questions
How much does a $30 overdraft fee cost as a yearly rate?
On $100 repaid after 5 days it is 2190.00%, because the fee is large compared with the amount and the time. The same $100 on a line of credit at 18% costs $0.25.
Is an overdraft fee interest?
Not usually. It is a charge for each item the bank pays. A line of credit linked to your account charges interest on the amount you borrow.
How is line-of-credit interest worked out?
Amount × APR ÷ 365 × days. $100 at 18% costs $0.05 a day.
What is the fee per item?
Take it from your bank's fee schedule. The $30 default is an example.
Does this cover every kind of overdraft cost?
No. It covers the item fee and the line-of-credit interest only.