Premium Bonds Calculator

Calculate expected returns and prize odds for NS&I Premium Bonds based on your holding.

Last updated: April 2026 · Source: NS&I

£

Min £25, Max £50,000

Expected Annual Return

£400.00

Expected Monthly

£33.33

Expected Prizes/Year

5.7

Monthly Win Chance

37.9%

Prize fund rate: 4% (tax-free). Most prizes are £25. Odds of winning per £1 bond per month: 1 in 21,000.

Returns are tax-free — equivalent to 5.0% in a taxable account for basic rate taxpayers.

Disclaimer

This calculator is provided for informational purposes only and should not be considered as financial or tax advice. All calculations are performed locally in your browser — no personal data is collected or sent to our servers. Rates and thresholds are sourced from HMRC and GOV.UK and are updated for the current tax year. Always verify results with HMRC or consult a qualified professional before making financial decisions.

How It Works

Premium Bonds do not pay interest. Instead, each £1 bond enters a monthly prize draw funded by a prize fund rate set by NS&I (currently 4.00% as of early 2026). The prize fund rate determines the total value of prizes distributed across all bondholders. With approximately £120 billion in bonds outstanding, the monthly prize fund is roughly £400 million, distributed as prizes ranging from £25 to £1 million.

Each £1 bond has an equal and independent chance of winning each month, generated by the ERNIE (Electronic Random Number Indicator Equipment) random number generator. The current odds of any single £1 bond winning a prize in any given month are approximately 1 in 21,000. The expected return equals the prize fund rate, but actual returns for individual holders vary significantly — particularly for smaller holdings where the probability of winning nothing in a given year is substantial.

For a £10,000 holding at 4.00% prize fund rate, the expected annual return is £400, but this is a statistical average across all bondholders. In practice, most holders of £10,000 will win several £25 prizes per year, occasionally a £50 or £100 prize, and very rarely a larger prize. The median return for small holdings is below the mean because large prizes skew the average upward. The calculator shows expected return alongside the probability distribution of likely outcomes.

Expected returns on £30,000 in Premium Bonds

  1. Holding: £30,000 (30,000 individual £1 bonds)
  2. Prize fund rate: 4.00%
  3. Expected annual return: £30,000 x 4.00% = £1,200
  4. Expected monthly prizes: approximately 1.4 prizes per month (mainly £25, occasional £50+)
  5. Comparison: a 4.5% easy-access savings account would pay £1,350/year guaranteed — but Premium Bond prizes are tax-free while savings interest above £1,000 PSA is taxable

Source: NS&I

Frequently Asked Questions

What is the Premium Bonds prize rate?
The annual prize fund rate is set by NS&I and changes periodically. Each £1 bond has an equal chance of winning a prize in the monthly draw. The minimum investment is £25 and the maximum holding is £50,000 per person.
Are Premium Bonds a good investment?
Premium Bonds are tax-free but offer no guaranteed return. They are best suited for risk-averse savers who have used their ISA allowance and Personal Savings Allowance. The expected return is lower than most savings accounts, but prizes are completely tax-free.