Premium Bond Calculator
Estimate your odds of winning a prize each month and your expected annual prize income for any NS&I Premium Bond holding, using the current 4.35% prize fund rate and 21,000 to 1 odds.
How Premium Bond Returns Work
Premium Bonds don’t pay interest. Instead, every £1 you hold is a numbered ticket in a monthly prize draw run by NS&I’s random number generator, ERNIE. The “prize fund rate” is simply the average payout across every bond in existence, expressed as a yearly percentage — what any individual actually wins depends entirely on luck. Here’s how the numbers fit together.
Every eligible £1 is one entry
Each pound invested buys a unique bond number, up to the £50,000 maximum per person. A bond only becomes eligible once it has been held for a full calendar month, so money moved in partway through a month misses that month’s draw and the next.
Entries = Holding (£), capped at £50,000The odds set your chance of winning something
Every eligible bond has the same fixed probability of winning a prize of any size in a given month, currently 21,000 to 1. More bonds means proportionally more chances, but each individual pound’s odds never improve — buying more bonds doesn’t make any single pound “luckier”.
P(win in a month) = 1 − (1 − 1/21,000)^entriesThe prize fund rate sets the average payout
NS&I sizes the total monthly prize pot so that, averaged across all £1 bonds in existence, the annualised payout equals the prize fund rate — currently 4.35%. Multiplying your holding by this rate gives your statistically expected annual prize income, even though your actual result will vary.
Expected annual prizes = Holding × prize fund rateSmall holdings see more variance than the average
The 4.35% figure is an average across the whole prize pool, which is skewed by a small number of very large prizes. With typical luck, holders with only a few hundred or thousand pounds often win less than the headline rate in most years, while larger holdings tend to track closer to it over time.
Realistic outcome ≈ most years: £0–small prizes, occasionally morePremium Bond Calculator
Based on the September 2026 rate & odds
Monthly Prize Breakdown
Approximate distribution of prizes at the current 4.35% prize fund rate and 21,000 to 1 odds. The vast majority of prizes are small — the eye-catching jackpots are a tiny fraction of the total pot.
| Prize value | Approx. number per month | Share of total prizes | Roughly 1 in |
|---|---|---|---|
| £1,000,000 | 2 | <0.01% | 1 in several billion |
| £100,000 | ~80 | <0.01% | 1 in hundreds of millions |
| £50,000 | ~160 | <0.01% | 1 in hundreds of millions |
| £25,000 | ~330 | <0.01% | 1 in tens of millions |
| £10,000 | ~800 | 0.01% | 1 in tens of millions |
| £5,000 | ~1,600 | 0.02% | 1 in several million |
| £1,000 | ~38,000 | 0.5% | 1 in several hundred thousand |
| £500 | ~114,000 | 1.4% | 1 in around 100,000 |
| £100 | ~1.9 million | 23% | 1 in around 6,000 |
| £50 | ~1.9 million | 23% | 1 in around 6,000 |
| £25 | ~4.6 million | 52% | 1 in around 2,500 |
Figures are approximate and rounded, based on NS&I’s published prize allocation for a total pool of roughly 22 million holders. Exact numbers vary slightly draw to draw and change whenever NS&I revises the rate or odds.
Premium Bonds vs a Savings Account
Premium Bonds and a standard easy-access savings account solve a similar problem in very different ways. Neither is better for everyone — it depends on your tax position, your holding size and how you feel about variable returns.
| Feature | Premium Bonds | Easy-access savings account |
|---|---|---|
| Return | Variable, prize-based, currently averaging 4.35% a year | Fixed or variable interest, published in advance |
| Guaranteed income | No — many holders win nothing in a given year | Yes, interest accrues on every pound held |
| Tax treatment | All prizes are entirely tax-free | Interest is taxable above the Personal Savings Allowance |
| Capital security | 100% government-backed via NS&I | Protected up to £85,000 per person per institution (FSCS) |
| Maximum you can hold | £50,000 per person | No limit |
| Access to your money | Withdraw any time, 3–5 working days to arrive | Typically instant or next-day access |
| Best suited to | Higher and additional rate taxpayers, or savers who enjoy the chance of a large prize | Savers who want predictable, guaranteed growth |
Premium Bonds FAQ
Answers to the questions people most often ask about how Premium Bonds actually pay out.
From the September 2026 draw, the Premium Bonds prize fund rate is 4.35%, up from 3.80% in July and August 2026. It represents the average annual return paid out in prizes across all bonds, not a guaranteed rate for any individual holder — some years you’ll win more than this, some years less, and some years nothing at all.
From the September 2026 draw, the odds are 21,000 to 1 for each eligible £1 bond in a given month. A holding of £1,000 therefore has roughly a 1,000 in 21,000 chance of winning at least one prize that month, which works out at just under 5%. Holding more bonds raises your overall chance of winning something, but each individual pound’s odds stay exactly the same.
It depends on your holding size, tax position and appetite for variable returns. With average luck, small holdings often win less than the headline prize fund rate, while larger holdings tend to track closer to it over time. Because all prizes are tax-free, higher and additional rate taxpayers who have used their Personal Savings Allowance sometimes find Premium Bonds more attractive than an equivalent taxable savings account.
The minimum purchase is £25, and the maximum any one person can hold is £50,000. Any amount above £50,000 is not eligible for prizes, and NS&I can reclaim any prize paid on ineligible bonds in error. Couples can each hold up to £50,000 in their own name, effectively doubling a household’s eligible total.
New bonds must be held for a full calendar month before they become eligible for the draw. Bonds bought at any point in a given month enter the draw two months later — for example, bonds bought in November are first eligible for the January draw. Reinvested prize winnings are entered into the draw the month after the win.
There is no fixed schedule. NS&I reviews the rate and odds periodically to reflect the wider savings market and its net financing target for the government. Both have moved several times recently — a cut to 3.30% in April 2026, a rise to 3.80% in July 2026, and a further rise to 4.35% from September 2026 — so it’s worth checking the current figures before relying on any published number.
No — the capital you put in is always returned in full if you cash bonds in, because NS&I is backed by HM Treasury. What varies is only the prize income, which can be zero in a given period. Unlike a savings account, Premium Bonds also don’t grow with compounding interest, and inflation can erode the real value of a holding that wins nothing over several years.