🎰 UK Premium Bonds Calculator

NSandI Premium Bonds are the UK's most popular savings product, held by over 21 million people. Instead of earning a guaranteed interest rate, each £1 bond you hold is entered into a monthly prize draw with the chance to win tax-free cash prizes ranging from £25 up to £1,000,000. Managed by National Savings and Investments (NSandI), a government-backed institution, Premium Bonds combine the security of a savings product with the excitement of a lottery. Because your capital is never at risk, you can withdraw your money at any time, making them an attractive option for savers who want safety with a chance of a big win.

Each bond costs exactly £1, with a minimum purchase of £25 and a maximum total holding of £50,000. The prizes are funded by a prize fund rate, which is approximately 4.4% for the 2026 tax year. This rate represents the average return across all bonds in the pool, but crucially, it does not mean each individual bondholder earns 4.4%. In fact, most bondholders win nothing at all in a given month, while a very small number take home large prizes. This is the fundamental trade-off: instead of receiving a small guaranteed return like a normal savings account, you are entered into a draw where your actual winnings may be far above or far below the headline rate.

The monthly draw features two £1,000,000 jackpot prizes, along with thousands of smaller prizes at levels of £100,000, £50,000, £25,000, £10,000, £5,000, £1,000, £500, £100, £50, and £25. The odds of any single £1 bond winning a prize in a given month are approximately 1 in 21,000, though this figure fluctuates as NSandI adjusts the prize pool. All winnings are completely free from UK Income Tax and Capital Gains Tax, which is a significant advantage for higher-rate taxpayers who would otherwise lose 40% or 45% of their savings interest to tax.

It is essential to understand that this calculator provides a statistical expectation, not a prediction. The expected value calculation shows what an average bondholder would win over an extremely long period, but individual results vary enormously. Some people with £50,000 in bonds will win multiple prizes per year, while others will win nothing. Over a single year, there is no guarantee of any return whatsoever. For a fair comparison, this tool also shows what your bonds would earn in a standard savings account paying a fixed interest rate.

The calculator uses standard probability theory to estimate your expected winnings from Premium Bonds. Here is how the maths works:

Expected Annual Winnings

The expected value is calculated as your total bond holdings multiplied by the prize fund rate:

For example, £10,000 in bonds at a 4.4% prize fund rate gives an expected annual return of £440. However, this is the average across all bondholders, not what you as an individual will necessarily win.

Probability of Winning at Least Once

The chance of winning at least one prize over 12 months is calculated using the complement rule:

Where p is the probability of a single bond winning in one month (approximately 1/21,000) and n is the total number of bonds you hold.

Jackpot Probability

The chance of winning one of the two £1,000,000 jackpots in a single month with one £1 bond is approximately 1 in 63 billion. Even with the maximum £50,000 holding, the monthly odds are about 1 in 630,000.

1. Enter the total value of your Premium Bond holdings in pounds (£).
2. Enter the number of months you want to simulate the expected winnings over.
3. Click Calculate to see your expected winnings, probability of winning, and comparison to savings.
4. Review the probability breakdown for any prize and the jackpot odds.
5. Compare the expected return to a standard savings account to decide which suits you.

Are Premium Bond winnings tax-free?

Yes. All Premium Bond prizes are completely free from UK Income Tax and Capital Gains Tax. You do not need to declare them on your tax return.

What is the maximum I can hold in Premium Bonds?

The maximum total holding is £50,000 per person. Each bond costs £1 and the minimum purchase is £25.

Will I definitely win the expected amount shown?

No. The expected value is a statistical average across all bondholders. Your actual winnings may be higher, lower, or zero. Individual results vary enormously, especially with smaller holdings.

What are the odds of winning the £1,000,000 jackpot?

With a single £1 bond, the odds are approximately 1 in 63 billion per month. Even with the maximum £50,000 holding, the monthly odds are roughly 1 in 630,000.

How often does the prize fund rate change?

NSandI reviews and adjusts the prize fund rate periodically based on market conditions and Bank of England base rate movements. Check the NSandI website for the current rate.

Should I choose Premium Bonds or a regular savings account?

If you want guaranteed returns, a savings account is safer. If you are a higher-rate taxpayer who values the tax-free aspect and are comfortable with uncertain returns, Premium Bonds can be attractive.

This tool is for informational purposes only and does not constitute financial advice. Consult a qualified financial professional for advice specific to your situation.

To maximise your Premium Bonds experience, aim to hold as close to the £50,000 maximum as possible. Statistically, the more bonds you hold, the more your actual winnings will converge toward the expected value. With small holdings of a few hundred pounds, you may well go years without winning anything, so consider whether a guaranteed interest savings account would be more suitable for that amount. Remember that all winnings are tax-free, which makes Premium Bonds particularly attractive for higher and additional rate taxpayers who have exhausted their Personal Savings Allowance. The prize fund rate changes periodically, so check the current rate on the NSandI website before making major decisions. If you are deciding between Premium Bonds and a Cash ISA, consider that the ISA provides a guaranteed return while bonds offer the potential for larger but uncertain payouts. You can hold both, as long as your total ISA contributions do not exceed your annual allowance.