How Mines multipliers are worked out

In Opal Mines each multiplier is 97% divided by the chance of finding that many opals in a row. With 3 mines on 25 tiles, the first opal has an 88% chance and pays 1.10x; three in a row has a 66.96% chance and pays 1.45x. More mines or more digs means a bigger multiplier and a smaller chance. However you play, the long-run return is 97%.

The formula

The field has 25 tiles and you choose 1 to 24 mines. Every safe tile you dig holds an opal and raises the multiplier.

After k opals with m mines, the multiplier is 0.97 x 25/(25 - m) x 24/(24 - m) x ... with one factor per opal. Each factor is one over the chance that the next tile is safe.

With 3 mines, 22 of the 25 tiles are safe: an 88% chance, so the first opal pays 0.97 / 0.88 = 1.10x. The second needs 21 safe tiles out of the 24 left, which makes the chance of two in a row 77% and the multiplier 1.26x.

Multipliers and chances by number of mines

Each cell is the chance of getting that far, then the multiplier paid if you cash out there. The screen shows multipliers rounded to two decimals; a cash-out is paid on the exact figure, to the nearest cent.

A game, step by step

Here is a $2 game with 5 mines. Before the first dig nothing is won yet; each line below is what a cash-out would pay at that point, and the chance of having got there.

1. Each cash-out is the $2 bet times the exact multiplier, rounded to the nearest cent.
2. A mine at any step ends the game and the $2 is lost, along with whatever the screen showed.
3. The next tile is always a fresh choice: the board was fixed when the game was bought and does not move.

Why every stop returns 97%

Because the multiplier is 0.97 divided by the chance, the chance times the multiplier is always 0.97. Cash out after one opal or after ten, with 1 mine or 24: the long-run return is 97%, a 3% house edge.

What changes is the swing. Few mines and an early cash-out win often and small; many mines and a late cash-out win rarely and big.

Stop or dig again?

Each new dig puts everything you have built up on the next tile. With 3 mines and 3 opals found, 19 of the 22 tiles left are safe, an 86.36% chance, and the multiplier would go from 1.45x to 1.68x.

0.8636 x 1.68 is the same 1.45 you would take by stopping. Digging on and cashing out are worth exactly the same on average, at every step, so no stopping rule beats 97%.

The mines are placed by the certified random number generator when the game is bought, before your first dig. Where you dig does not change your chances.

The limits

The 5,000x cap is reached at 19 opals with 5 mines, 12 opals with 10 mines and 8 opals with 15 mines. On a $100 bet the $5,000 cap comes first, at 50x.

1. A game's bet is 50 cents to $100, in 50 cent steps.
2. The highest multiplier is 5,000x and the most one game pays is $5,000.
3. A dig that would pass either cap is refused before the tile is looked at: you cash out, and are never paid short.
4. Finding every safe tile cashes out by itself.
5. A game left untouched for 24 hours is cashed out for you, or its bet returned if no opal was found.

Questions

What are the odds of hitting a mine on the first click?

The number of mines out of 25: 4% with 1 mine, 12% with 3, 20% with 5, 40% with 10 and 96% with 24.

Do more mines give a better return in Mines?

No. Every mine count and every cash-out point returns 97% over the long run. More mines only make wins bigger and rarer.

When should I cash out in Mines?

No point is better on average: stopping and digging again are worth the same. Cash out when the amount on screen is one you are happy to keep.

What is the biggest multiplier in Opal Mines?

Up to 5,000x, with a $5,000 limit on one game. A single opal with 24 mines pays 24.25x.

Is Opal Mines on both the Australian and US sites?

Yes. The rules, the 97% return, the limits and the free practice mode are the same on both.

Play Opal Mines free in practice

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Updated 2026-11-05.