How Betting Odds Work

Fractional odds: the traditional Irish format

Fractional odds are the classic form used in Irish and British betting shops, especially for horse racing. They read as profit-to-stake.

• 5/2 means for every €2 you stake, you win €5 profit if it lands.
• 2/1 ("two to one") returns €2 profit per €1 staked.
• 1/2 is an odds-on price: you stake €2 to win €1 profit.

Total return includes your stake back. A €10 bet at 5/2 returns €35 (€25 profit + €10 stake).

To work out profit from any fractional price: profit = stake × (numerator ÷ denominator). At 7/4 with a €20 stake, profit = €20 × (7 ÷ 4) = €35, and your return is €55.

Evens is written as 1/1 or Evs — a €10 stake wins €10 profit.

Decimal odds: the format most apps default to

Decimal odds show your total return per €1 staked, stake included. Most betting apps in Ireland let you switch between fractional and decimal in the settings — many bettors prefer decimal for accumulators because the maths is simpler.

• 3.50 means a €1 stake returns €3.50 total (€2.50 profit + €1 stake).
• 2.00 is evens — €1 returns €2.
• 1.50 is odds-on — €1 returns €1.50.

Total return = stake × decimal odds. A €10 bet at 3.50 returns €35, the same as 5/2 above — because they're identical prices in different clothing.

Conversion is quick: decimal = (fraction) + 1. So 5/2 = 2.5 + 1 = 3.50. Going the other way, 3.50 − 1 = 2.50 = 5/2.

Implied probability: what the odds are really saying

Every price contains a probability. Converting odds to implied probability tells you how likely the bookmaker rates an outcome — and helps you judge whether a price is worth taking.

For decimal odds: implied probability = 1 ÷ decimal odds × 100.

• 2.00 → 1 ÷ 2.00 = 50%
• 3.50 → 1 ÷ 3.50 = 28.6%
• 1.50 → 1 ÷ 1.50 = 66.7%

For fractional odds: implied probability = denominator ÷ (numerator + denominator) × 100. So 5/2 = 2 ÷ (5+2) = 28.6% — matching the decimal.

If you think an outcome is more likely than the implied probability suggests, that's a value bet in theory. If your own estimate is lower, the price is poor. This is the single most useful skill in reading odds: stop seeing prices as payouts and start seeing them as probabilities.

The bookmaker margin: why the percentages add up past 100%

Add the implied probabilities of every outcome in a market and they exceed 100%. That extra slice is the bookmaker's margin (also called the overround or "juice"). It's how the operator builds in profit regardless of results.

Example — a two-way market both priced at 1.90:

• 1 ÷ 1.90 = 52.6% for each side
• 52.6% + 52.6% = 105.2%

That 5.2% above 100% is the margin. A fair market with no margin would price both sides at 2.00 (50% each). The tighter the margin, the better value you get.

Our sampled odds data shows meaningful differences between Irish-licensed operators. Average margins across the markets we sampled:

• Betfair — 4.29% (213 markets sampled)
• Unibet — 5.73% (191 sampled)
• Ladbrokes — 5.83% (193 sampled)
• Betway — 6.32% (195 sampled)
• William Hill — 6.96% (219 sampled)
• Paddy Power — 6.93% (195 sampled)
• 888sport — 7.13% (219 sampled)
• bet365 — 7.44% (30 sampled)
• BoyleSports — 7.51% (195 sampled)
• BetVictor — 7.51% (188 sampled)
• LiveScore Bet — 8.37% (193 sampled)

Lower margin means more of the true probability is returned to you as price. Note bet365's figure is from a small 30-market sample, so treat it as indicative rather than conclusive.

A worked example: comparing prices across operators

Say you want to back a horse at Leopardstown and the true chance is genuinely around 33% (a fair price of 3.00 decimal, or 2/1).

Because of margin, no bookmaker offers exactly 3.00. Suppose you find these prices on the same runner:

• Operator A: 2.90 (implied 34.5%)
• Operator B: 3.10 (implied 32.3%)

Stake €50 on each in turn:

• At 2.90 your return is €50 × 2.90 = €145 (€95 profit)
• At 3.10 your return is €50 × 3.10 = €155 (€105 profit)

Same bet, same stake — €10 more profit purely from shopping the better price. Over a season of hundreds of bets, that gap compounds. This is why the best-price share matters: in our sample Betfair returned the top available price on 53% of markets and Ladbrokes on 22%, while several operators landed the best price under 15% of the time. Comparing odds Ireland-wide before you stake is the most reliable edge available to a recreational bettor — it requires no prediction skill, just discipline.

How odds move: markets, live betting and cash out

Odds are not fixed. They drift or shorten as money comes in, team news lands, or an in-play match develops. A shortening price (odds getting smaller) means more confidence or more money on that outcome; a drifting price (getting bigger) means the opposite.

Live betting recalculates prices continuously as a match unfolds — a goal, a red card or a break of serve in an ATP or WTA match will move everything instantly. All the operators covered here offer live betting, and most offer Cash Out, which lets you settle a bet early at the current implied value rather than waiting for the final result. Cash Out prices carry their own built-in margin, so the amount offered is usually a little below the raw mathematical value of your position.

Bet Builder markets — combining several selections in one game, such as match result, cards and both teams to score — multiply the individual prices together, and the combined margin is larger than a single market. That's the trade-off for the convenience: bigger potential returns, but more of the operator's margin baked in.

Odds formats, settings and choosing where to bet

Practical points for reading odds on Irish apps:

• You can switch between fractional and decimal in account settings on every major app. Pick whichever you calculate faster with.
• "SP" (Starting Price) in racing means you take whatever the price is at the off, rather than locking in now. Taking an early price protects you if the horse shortens.
• "Each-way" splits your stake between the win and a place at a fraction of the odds (commonly 1/4 or 1/5), relevant for racing and golf outrights.

When deciding where to bet, judge odds alongside safety and cashiering. Every operator here is licensed, and Paddy Power, BoyleSports and Novibet are noted in our data as regulated by the Gambling Regulatory Authority of Ireland (GRAI). Withdrawal times across the board are quoted at 0–24 hours with a €10 minimum deposit, and all support Debit Card and PayPal, with Apple Pay and Revolut Pay available at bet365 and Paddy Power.

Choose Betfair or Unibet if consistently tight margins are your priority. Choose Paddy Power or bet365 if you value app quality and payment flexibility alongside competitive prices. Avoid fixating on a single bookmaker if you're serious about long-term value — the operator with the best price varies market to market.