Should You Pick Birthday Numbers in the Lottery?
Your birthday, your partner's, the kids'... Picking the dates that matter to you is one of the most popular ways to choose lottery numbers. It feels personal, and if they ever come up, it makes for a great story!
But is it actually a good idea? Birthday numbers are just as likely to be drawn as any other numbers, so is there a catch? We went through the winners of 6,890 draws since 2012, from Saturday Lotto to the US Powerball, and the answer is surprisingly clear. Let's find out!
- Are birthday numbers less likely to win?
- So what's the catch?
- How can we tell which numbers people pick?
- What the draws reveal
- The most popular numbers
- How much could it cost you?
- So, should you pick birthday numbers?
Are birthday numbers less likely to win?
Not at all! The balls don't know what day it is. Every combination has exactly the same chance of being drawn: in Saturday Lotto, 1, 2, 3, 4, 5, 6 is just as likely to come up as any other combination, at 1 in 8,145,060.
If you want to put that to the test, our Saturday Lotto simulator lets you play the same numbers as many times as you like, for free.
So what's the catch?
The catch is that you might have to share. Birthday numbers only go up to 31, and if you use months too, most of them are 12 or under. In Saturday Lotto, 14 of the 45 numbers can never be part of a birthday!
So when the winning numbers are low, a lot more people tend to have them. And in Australia, the prizes in each division are a share of a prize pool: the more winners, the smaller everyone's prize. The only exception is Weekday Windfall's Division 1, a fixed $1 million for every winner.
How can we tell which numbers people pick?
Lotteries don't publish which numbers people pick, but the winners give it away. In every draw, we compare two prizes: matching 5 numbers and matching 4 numbers in Saturday Lotto, for example.
Pure chance tells us how many tickets should match 5 numbers for every ticket that matches 4. If the winning numbers were popular picks though, the number of 5-number winners goes up much faster than the 4-number winners, because each extra popular number matched makes it even more likely. So by comparing the two, we can tell how popular the winning numbers were, without even knowing how many tickets were sold.
Take the US Powerball draw of 16 June 2012, with the winning numbers 8, 14, 15, 16, 27. Based on the lower prize, chance predicted 293 winners of the higher prize, but there were 866: that's 196% more! At the other end, the US Mega Millions draw of 31 December 2013 (8, 12, 34, 52, 58) had 53% fewer winners than chance predicted.
What the draws reveal
Now let's do that for every draw, and group them by how many of the winning numbers were birthday numbers, from 1 to 31. If birthday numbers made no difference, every group would sit around 1, what pure chance predicts.
| Lottery | Draws | Winners when half or fewer were birthday numbers | Winners when all were birthday numbers |
|---|---|---|---|
| Australia Saturday Lotto | 513 | 2% fewer than chance | 11% more than chance (42 draws) |
| Weekday Windfall | 1,154 | 3% fewer than chance | 15% more than chance (101 draws) |
| Oz Lotto | 233 | 3% fewer than chance | 7% more than chance (7 draws) |
| Australia Powerball | 445 | 35% more than chance | 32% more than chance (180 draws) |
| US Powerball | 1,789 | 21% more than chance | 83% more than chance (27 draws) |
| US Mega Millions | 1,358 | 6% fewer than chance | 34% more than chance (26 draws) |
| Euro Millions | 1,026 | 5% fewer than chance | 16% more than chance (83 draws) |
| Euro Jackpot | 372 | 3% fewer than chance | 9% more than chance (39 draws) |
The pattern is the same everywhere: the more birthday numbers among the winning numbers, the more winners. It's strongest in the US Powerball, where draws with only birthday numbers had 83% more winners than chance would predict. The more numbers above 31 a lottery has, the more a draw of only birthday numbers stands out. In the Australian Powerball on the other hand, 31 of its 35 numbers could be a birthday, so there's a lot less of a difference to see.
The most popular numbers
We can go one step further and look at each number on its own: on average, did draws including that number have more winners or fewer? Here are the numbers from 1 to 45.
There's a clear step after 31: the numbers that can't be part of a birthday are consistently less popular than the ones that can. The most popular of all in our data were 13, 11, 7. Lucky numbers, anyone?
How much could it cost you?
When a prize is shared, more winners means a smaller slice for each of them. If a division has 83% more winners, each of them takes home around 45% less than if the numbers had been average picks.
And that's for matching 5 numbers. The effect grows with every popular number matched, so for the Jackpot, where you need every number, the risk of sharing is even bigger. In Saturday Lotto and Oz Lotto, a shared Division 1 can mean the difference between a few million and a lot less.
In the US, the smaller prizes are fixed amounts that aren't shared, so birthday numbers only cost you if you win the Jackpot. The same goes for Weekday Windfall's $1 million Division 1, which is never shared!
So, should you pick birthday numbers?
If they mean something to you, go for it: they're just as likely to win as any other numbers. Just know that if they do come up, you're more likely to have company.
If you'd rather keep a Jackpot to yourself, here are a few tips:
- Mix in a few numbers above 31, the ones birthday players can't pick
- Don't rely on the same few "lucky" numbers as everyone else, like 7 or the numbers up to 12
- A Quick Pick chooses numbers at random, so it avoids the birthday crowd automatically
None of this changes your odds of winning, only how much you would win. Good luck!
Want to see how your favourite numbers would do? Try them for free in our lottery simulators, or find out which Australian lottery has the best odds.
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