Premium Bonds Calculator

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

Source: NS&I

Konstantin Iakovlev

By Konstantin Iakovlev · Founder, Calks.uk

Last updated: · Verified against HMRC and GOV.UK 2026/27 rates

£

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.

How Premium Bonds work. Issued by National Savings & Investments (NS&I, UK Treasury). £1 = 1 bond = 1 entry in monthly prize draw. Buy £25-£50,000 max holding. Average prize rate 2026: 4.15% (i.e., expected return on average across all bondholders). Tax-free winnings. Capital safe — Treasury-backed, £1 invested = £1 returned (cash back any time). Monthly ERNIE (Electronic Random Number Indicator Equipment) draw: £1M jackpot × 2; £100k × 4-5; £50k × 9-10; thousands of smaller prizes from £25 to £25k.

Premium Bonds vs savings accounts. Average return 4.15% sounds competitive with best savings accounts BUT: median return is significantly lower. Half of holders earn LESS than 4.15%; many earn 0%. Higher holdings (£25k+) approach the 4.15% mean reliably; smaller holdings (£1k-£5k) have high variance — many months £0, occasional lucky £25-£100. £50k held for 12 months expects ~£2,075 win on average. Best for: higher-rate taxpayers (tax-free), large emergency cash holdings, those who enjoy the prize lottery aspect.

Probability of winning. Odds of any prize per £1 bond per month (2026): 22,000 to 1. Holding £1,000: 22 chances per month — about 0.05 prize wins/month on average. Holding £10,000: 0.45 wins/month average. Holding £50,000: 2.3 wins/month — most months you win, occasional larger prizes. Odds of jackpot per bond: 60 BILLION to 1. Even at max £50,000 holding for 50 years (600 months): 1-in-2,000 chance of ever winning £1M. Don't buy expecting jackpot — buy for low-tail-risk diversification + tax-free yield.

Tax advantages — when Premium Bonds win. All prizes tax-free, no PSA used. Higher-rate (40%) taxpayer earning 4.5% savings rate: effective after-tax 2.7%. Same person in Premium Bonds: 4.15% tax-free (effective beat by 1.45%). Additional-rate (45%) taxpayer: 2.475% net savings vs 4.15% Premium Bonds (1.675% advantage). For basic-rate taxpayers within Personal Savings Allowance £1,000: Premium Bonds advantage shrinks or vanishes. Compare against your specific tax bracket.

How to manage Premium Bonds. Buy online at nsandi.com or via post. Minimum £25 purchase. Prizes paid into bank account (auto-credit) or reinvested into more bonds. Check wins: free Prize Checker app, NS&I website. Withdraw cash any time — 1-3 working days. Useful tax-free home for: 6-month emergency cash, savings for distant goal where ISA already maxed, higher/additional rate taxpayer at PSA limit. Boring but reliable: holds value, can be redeemed any time, win something on average but no guarantee any individual month.

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 actual return on Premium Bonds?
Prize rate 2026: 4.15% expected return on average across all bondholders. Median return is LOWER — distribution skewed by infrequent large prizes. £1,000 holding: ~22 chances/month, perhaps 0-2 wins/year averaging £25-£100. £10,000 holding: ~5 wins/year averaging £25-£300. £50,000 (max): roughly approaches 4.15% reliably. Variance reduces significantly at higher holdings. Compare against best easy-access savings (4.5-5.0%): Premium Bonds need £20k+ holding and higher-rate tax bracket to beat after-tax savings rates.
Are Premium Bonds tax-free?
Yes — all winnings tax-free including the £1M jackpot. Doesn't use Personal Savings Allowance (PSA) or Capital Gains allowance. Particularly valuable for: higher-rate (40%) taxpayers above £500 PSA; additional-rate (45%) taxpayers with £0 PSA. £50,000 in Premium Bonds: expected £2,075 tax-free vs £50,000 at 4.5% savings = £2,250 gross, £1,350 net for higher-rate taxpayer. Premium Bonds beat taxable savings for higher-rate taxpayer at the maximum holding. Worth less for basic-rate taxpayer within PSA limit.
Can I lose money on Premium Bonds?
No capital loss — your £1 buys 1 bond, redeemable at £1 any time. NS&I is HM Treasury-backed = government guarantee (100% safe). BUT: inflation erodes purchasing power over time. If you win £0 for 12 months at 3% inflation, real value of £10,000 holding falls to £9,709. Premium Bonds beat 0% interest cash holding ON AVERAGE — but worst-case scenarios (multi-year zero wins) DO happen for smaller holdings. For £100-£1,000 holdings: usually win less than expected over multi-year periods due to high variance.
How to maximise Premium Bonds odds.
Hold the maximum £50,000 — reduces variance, approaches expected 4.15% return reliably. Reinvest all winnings into more bonds — boosts holding, increases prize chances. Use online prize checker monthly to confirm no missed wins. NS&I will pay missed prizes back any time (no expiry). Best for: emergency fund of £25k+ (instant access, tax-free, decent return); higher-rate taxpayers above PSA; large cash holdings outside ISA. Worst for: small holdings (£100-£1,000) — high variance, often beaten by regular savings accounts.