Estimate your Nationwide overdraft cost
Use this quick tool to estimate interest on an arranged overdraft. You can also model a monthly charge cap if your account terms include one.
Educational estimate only. Nationwide account terms can change and may include different rules for arranged and unarranged borrowing. Always confirm exact charges in your account documents.
If you want a straightforward way to project potential overdraft charges, this Nationwide overdraft calculator gives you a practical estimate in seconds. It is designed for UK current-account users who want to understand how daily interest, overdraft balance, and time overdrawn interact.
How this Nationwide overdraft calculator works
The calculator converts your EAR (Equivalent Annual Rate) into an effective daily rate, then estimates the interest for the number of days you stay overdrawn.
- Step 1: Remove any interest-free buffer from your balance.
- Step 2: Convert EAR to daily rate.
- Step 3: Apply daily compounding over your selected number of days.
- Step 4: If you enter a monthly cap, limit the result to remaining cap room.
This gives you an estimate of likely overdraft interest for planning and comparison purposes.
Understanding key terms
EAR vs APR
For overdrafts in the UK, you often see EAR instead of APR in day-to-day explanations. EAR is useful because it reflects compounding over a year, making comparison easier across products.
Arranged overdraft
An arranged overdraft is borrowing up to a pre-agreed limit with your bank. Most modern pricing is interest-based, but exact terms vary by account type and promotional period.
Unarranged overdraft
If your balance goes beyond an arranged limit or no overdraft is set up, extra restrictions or charges may apply. This calculator flags when your entered borrowing is above your arranged limit so you can review this risk.
Input guide for better estimates
- Overdraft used: Your typical negative balance during the period.
- Arranged limit: Optional, but useful for warning checks.
- EAR: Enter the rate listed in your current account documents.
- Days overdrawn: How long you expect to stay in overdraft.
- Interest-free buffer: Some accounts may not charge on the first portion.
- Monthly charge cap: Use only if relevant to your account terms.
- Already charged this month: Helps estimate remaining costs before cap.
Worked examples
Example 1: Everyday overdraft use
If you borrow £500 for 30 days at 39.9% EAR, the calculator estimates the interest cost for the month. This helps you decide whether a short-term transfer or faster repayment could be cheaper.
Example 2: You clear some balance mid-month
Suppose you start at £700 overdrawn, then repay £300 after two weeks. Run two calculations (14 days at £700, then 16 days at £400) and add the results. This gives a much more realistic estimate than assuming one fixed balance all month.
Example 3: Account with a monthly cap
If your account terms include a monthly maximum and you have already incurred charges, add both fields to see your likely remaining cost. This is useful for budgeting in tight months.
How to reduce overdraft charges
- Pay in money earlier in the month where possible.
- Set balance alerts so you know when you are close to your limit.
- Prioritise highest-cost borrowing first.
- Consider whether a low-rate personal loan or 0% purchase plan fits your situation better.
- Review direct debits and subscriptions that trigger avoidable overdraft usage.
- Check if your account has tools such as spending insights or safety buffers.
Frequently asked questions
Is this an official Nationwide calculator?
No. This is an independent educational tool designed to help with planning. It is not affiliated with Nationwide Building Society.
Will my real charge match exactly?
Not always. Real charges depend on exact posting dates, account-specific terms, and whether your balance changes during the period. Use this as a close estimate, not a guaranteed figure.
Can I use this for other UK banks?
Yes. If you enter the correct EAR and account rules, this calculator can estimate overdraft cost for many UK current accounts.
Final thoughts
A good overdraft calculator turns vague money stress into concrete numbers. Once you can see your likely cost, you can make faster, calmer decisions—whether that means repaying sooner, adjusting spending, or comparing alternatives.
Last updated: February 2026. Always verify current rates and overdraft policy details directly in your bank account information.