The same game name has meant three different sets of odds
A lottery is one of the very few gambling products whose exact probabilities are published, calculable and beyond dispute. That makes it an unusually good place to learn a habit that applies everywhere else: an odds figure without a date is not information. Ireland's Lotto has been rebuilt more than once, and each rebuild moved the jackpot odds by an order of magnitude. Anyone quoting a number for this game without saying which version of it they mean is quoting something that may have stopped being true a decade ago — and the same failure mode, harder to spot, is what keeps stale figures alive across the rest of the industry.
The versions, in order
Each change to the matrix altered the jackpot odds, the ticket price, or both, and each has a date attached.
It began as six from thirty-six
The first draw was held on Saturday 16 April 1988 for a jackpot of £147,059. As a 6/36 game the jackpot odds were 1 in 1,947,792, and at the initial price of £0.50 per line every possible combination could have been bought for £973,896.
Then six from forty-seven
A new operator changed the game to 6/47 and raised the price from €1.50 to €2 per line, effective for draws beginning 3 September 2015. The jackpot odds became 1 in 10,737,573 — more than five times longer than the original game.
A cap, and a long sequence of rollovers
Under rules introduced in 2015 the jackpot is capped once it reaches a new all-time high, with further funds flowing to the next prize tier with a winner. For a record sixty-three consecutive draws from 9 June 2021 to 12 January 2022 no ticket matched all six numbers.
A return to six from forty-five was announced
A change back to the 6/45 matrix used from 2008 to 2015 was announced for 3 September 2026, alongside a reduced jackpot cap. We have not confirmed this directly with the operator, so treat post-dated odds figures with care.
The questions that arrive most often
Why do published odds for the same lottery differ so much?
Because the game itself has been rebuilt. As a 6/36 game the jackpot odds were 1 in 1,947,792; under the 6/47 matrix introduced for draws beginning 3 September 2015 they are 1 in 10,737,573. Both figures are correct for their own version and both circulate freely without dates attached. Adding two numbers to the pool from which six are drawn is not a cosmetic change — it lengthens the jackpot odds by a factor of more than five.
What does capping a jackpot actually do?
Under rules introduced in 2015, once the jackpot reaches a new all-time high it is capped at that level, and money that would otherwise have gone on increasing it is instead divided in each draw among ticketholders in the next-highest prize tier that has at least one winner. It does not change your chance of matching six numbers. It changes where the money goes when nobody does, which is a distribution question rather than a probability one.
If a jackpot has rolled over many times, is a win overdue?
No. Each draw is independent, and a long sequence of rollovers changes nothing about the next one — the record run of sixty-three consecutive draws without a jackpot winner between 9 June 2021 and 12 January 2022 was extraordinary and still tells you nothing about the draw that followed it. A larger jackpot changes what a win would be worth, not how likely it is. The outcome is not predictable, and no pattern in past draws makes it so.
