Free bets explained: how to calculate their real value
Why free bet stake isn't returned, how to value a free bet in expected-value terms, and how to maximise value from welcome offers and reload promotions.
A free bet is a wager funded by the bookmaker rather than the punter. The catch — and it's a meaningful one — is that the stake is not returned with winnings. You only keep the profit on a winning free bet, not the £10 (or whatever) the bookmaker handed you.
Understanding what a free bet is actually worth in expected-value terms is the single most useful skill for evaluating welcome offers, reload promotions, and "bet £10 get £30" sign-up deals.
Stake-returned vs free bet — the critical difference
Two £10 bets at 2.00 (Evens):
- Cash £10 bet at 2.00: if it wins, you get £20 back (£10 stake + £10 profit). If it loses, you're down £10.
- Free £10 bet at 2.00: if it wins, you get £10 back (profit only — stake doesn't return). If it loses, you're flat (no cash was at risk).
A free bet always returns less than a cash bet at the same price because the stake is "stake-not-returned" (SNR). That fact alone tells you a £10 free bet is not worth £10 in expected value.
How to value a free bet
The expected value of a free bet at decimal odds D is roughly:
EV of a free bet ≈ free-bet amount × (D − 1) × P(win)
Where P(win) is the true probability of the bet landing.
Worked example: a £30 free bet at 2.00.
- Bookmaker odds: 2.00 (implied probability 50%, assume the implied probability is close to true probability for simplicity)
- EV: £30 × (2.00 − 1) × 0.50 = £15
A £30 free bet at Evens is worth roughly £15 in expected value — half the headline number.
Why bookmakers use free bets
Three reasons free bets are favoured over cash bonuses:
- Stake-not-returned mechanics mean the bookmaker pays out less per winning bet, regulatory cost-of-customer is lower.
- Free bets force the customer to place a bet to extract any value — engagement metric.
- Many free bets carry minimum-odds restrictions (often 1.50 or higher) that the bookmaker selects to favour their margin curve. A free bet at 1.50 returns even less in expected value than one at 2.00.
Maximising free bet value
Two strategies UK punters use to extract maximum value from free bet offers:
Higher odds within terms
A £10 free bet at 5.00 (4/1) is worth more in expected value than the same bet at 2.00. EV scales with (D − 1). Even at the same implied true probability, picking the longer odds within the bookmaker's minimum-odds rule extracts more value. The trade-off: longer-odds selections lose more often, which feels worse in any individual instance.
Matched betting
Combine the free bet with a lay bet at an exchange to extract a guaranteed cash return. This is the basis of the UK matched betting industry. Typical extraction rate is 75-80% of the free-bet face value as guaranteed cash — significantly better than the ~50% EV from raw bet-and-hope. The Free Bet tab on the main betting calculator works out the exact lay stake to hit your target extraction rate. See also the lay betting guide for the lay mechanics.
Welcome offer comparison
When comparing bookmaker welcome offers, headline numbers ("Bet £10 get £30") rarely reflect actual value. Three things to check:
- Free bet face value (the £30)
- Minimum odds restriction (often 1.50, sometimes 2.00 or higher)
- Whether the free bet is stake-not-returned (almost always yes) or stake-returned (rare, but worth more)
A "£50 free bet at min 2.00" is typically worth more in cash terms than a "£100 free bet at min 1.50" once you do the EV maths, even though the headline numbers favour the second.
For the deeper context on why bookmakers structure free bets the way they do — and why the £10 face value is not what you're actually getting — see the foundational reference on bookmaker margin. Free bets are a marketing veneer over the same underlying maths.