Thunderball odds explained: chances for every prize level

How Thunderball works

Thunderball is a UK lottery game with draws four times a week: Tuesday, Wednesday, Friday and Saturday. Each line has two parts. You choose five main numbers from 1 to 39, and one Thunderball from a separate set numbered 1 to 14.

The top prize goes to lines that match all five main numbers, in any order, plus the Thunderball. Unlike many big lottery games, there are prizes for matching the Thunderball on its own, so even a line with no main numbers can win something. Because the Thunderball is drawn from its own machine, it can be the same number as one of your main choices.

How the top prize odds are worked out

First, count the possible sets of five main numbers. The order in which they are drawn does not matter, so this is a combinations calculation. There are 575,757 different ways to choose 5 numbers from 39.

Then bring in the Thunderball. Each of those 575,757 sets can be combined with any of the 14 Thunderball numbers. Multiplying gives 575,757 times 14, which is 8,060,598. Exactly one of those lines will match the draw, so the odds of winning the top prize are 1 in 8,060,598.

That is a long shot, but a much shorter one than the big jackpot games. With four draws a week, someone playing a single line in every draw would still expect to wait, on average, many thousands of years for a top prize. Probability does not run on a schedule, of course: it could happen in any draw, or never.

Odds for every Thunderball prize level

For one line, the odds are:

• 5 numbers + Thunderball (top prize): 1 in 8,060,598
• 5 numbers: 1 in 620,046
• 4 numbers + Thunderball: 1 in 47,415
• 4 numbers: 1 in 3,647
• 3 numbers + Thunderball: 1 in 1,437
• 3 numbers: 1 in 111
• 2 numbers + Thunderball: 1 in 135
• 1 number + Thunderball: 1 in 34.76
• Thunderball only: 1 in 28.97
• Any prize: 1 in 12.38

There is an interesting quirk in the middle of this list. Matching three main numbers without the Thunderball, at 1 in 111, is actually more likely than matching two main numbers with it, at 1 in 135. Getting the Thunderball right is a 1 in 14 event, which is harder than picking up one extra main number, so the tier with the Thunderball ends up slightly rarer.

At the bottom, the Thunderball only level is 1 in 28.97 rather than 1 in 14. That is because it needs the Thunderball and no main numbers at all. A line that matches the Thunderball and one or two main numbers falls into a different level instead.

Overall, about one line in twelve wins a prize. Most of those wins come from the three lowest levels, which all depend on the Thunderball.

Thunderball compared with UK Lotto

Thunderball and UK Lotto are both run in the UK, but they are built very differently. UK Lotto asks you to match six numbers from 1 to 59, which gives 45,057,474 possible combinations. Thunderball splits the line into five numbers from a smaller pool of 39 and one extra ball from 14, giving 8,060,598 combinations.

The result is that the Thunderball top prize is more than five times easier to win than the UK Lotto jackpot. Lower down, the picture flips. UK Lotto's chance of winning any prize is about 1 in 9.23, slightly better than Thunderball's 1 in 12.38, but almost all of that comes from UK Lotto's match-2 level at 1 in 10.26. Thunderball spreads its small wins across levels that lean on the extra ball instead. Neither structure is better or worse; they simply share out the probability in different ways, and both are fixed by the number ranges.

No system can beat the odds

Every Thunderball draw is independent. The machines do not track previous results, so a number that has been missing for weeks is not due, and a number that has just appeared is not less likely to turn up again. Thinking otherwise is the gambler's fallacy.

A quick pick, your own favourite numbers and a line from our random number generator all have exactly the same chance. Random numbers do have one small practical benefit. Lots of players choose birthdays, which means numbers up to 31 are chosen more often. Spreading your picks across the full 1 to 39 range can only affect how a prize might be shared with other players who chose the same line; it changes nothing about your chance of winning.

Play responsibly

You must be of legal age to play, and the minimum age can differ between countries, so check the current rules before you buy. Decide how much you are comfortable spending before you play, and stick to it. The lottery should be a bit of fun, not a way to make money. Rules and prize structures can change, so check official lottery sources for the latest details.

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