What's a free bet really worth?
Less than it says on the tin, and more than most people get out of it.
A "£10 free bet" isn't £10. Because the stake isn't returned, the only thing it can ever pay you is the winnings. Back it at 5.0 and a win pays £40. Lose and you get nothing. Most punters stick it on a favourite, it loses half the time, and the bookie has done its job.
The maths way is to lay the same selection at a betting exchange. You become the bookie for that one outcome. Whatever happens, one side wins, and the numbers are set so both outcomes leave you with the same amount. That's the whole trick.
Stake returned vs stake not returned
| £10 free bet at 5.0 | Stake not returned (SNR) | Stake returned (SR) |
|---|---|---|
| Pays if it wins | £40.00 | £50.00 |
| Lay stake at 5.2, 2% commission | £7.72 | £9.65 |
| Locked in whatever wins | £7.57 | £9.46 |
Nearly every UK free bet is SNR. If the terms don't say, assume it is.
Turn a free bet into cash: worked example
Here's a £10 SNR free bet, step by step. These are the default numbers in the calculator, so you can follow along.
- Find a selection with close odds. Pick a selection at around 4.0 to 8.0 where the exchange lay price is close to the bookmaker price. Example: back 5.0 at the bookie, lay 5.2 at the exchange.
- Enter the numbers. Free bet value £10, back odds 5.0, lay odds 5.2, commission 2%. Leave the type on Free bet (SNR).
- Place the lay first. Lay £7.72 at 5.2 at the exchange. Your liability is £32.43, so your exchange balance has to cover it.
- Place the free bet. Place the £10 free bet at 5.0 at the bookmaker, straight after the lay is matched.
- Collect either way. If the bookie bet wins: +£40.00 at the bookie, −£32.43 at the exchange = £7.57. If it loses: +£7.57 at the exchange after commission. You keep £7.57 whatever happens.
Why lay first? If the exchange price moves before your lay is matched, you can still pick a different selection for the free bet. Get it the other way round and you're stuck with a bad match.
The maths
Three lines do all the work. B is the free bet, Ob the back odds, Ol the lay odds and c the exchange commission as a decimal (2% = 0.02).
Lay stake (SNR) L = B × (Ob − 1) ÷ (Ol − c) Lay stake (SR) L = B × Ob ÷ (Ol − c) Liability = L × (Ol − 1) If bookie wins = B × (Ob − 1) − L × (Ol − 1) If bookie loses = L × (1 − c) Retention = locked-in profit ÷ B
Dividing by (Ol − c) is what balances the two outcomes after commission. The calculator rounds to the penny only when it shows you the answer, never mid-sum.
Retention: what's good?
Retention is the share of the free bet you keep as cash. For SNR free bets, 70–80% is a typical target. On reloads I aimed for about 80%.
| £10 SNR free bet, 2% commission | Locked in | Retention |
|---|---|---|
| Back 2.0, lay 2.04 | £4.85 | 48.5% |
| Back 5.0, lay 5.2 | £7.57 | 75.7% |
| Back 6.0, lay 6.2 | £7.93 | 79.3% |
| Back 10.0, lay 10.5 | £8.42 | 84.2% |
Higher odds keep more, because the stake you never get back is a smaller slice of the pot. The catch is liability: the 10.0 example needs £81.58 in your exchange account.
Underlay and overlay
The balanced lay makes both outcomes equal. Move the slider and you choose a side instead. Underlay a £10 free bet by 10% at 5.0/5.2 and you make £10.81 if the bookie bet wins but £6.81 if it loses, against £7.57 either way when balanced. It's a bet on the result, so treat it as one.
FAQs
What does SNR mean on a free bet?
Stake not returned. If your free bet wins you get the winnings but not the stake. A £10 SNR free bet at 5.0 pays £40, not £50. Nearly every UK bookmaker free bet works this way.
How much is a £10 free bet actually worth?
If you just bet it, anything from £0 to the winnings. If you lay it at an exchange, usually about £7 to £8 in cash whatever wins. At 5.0 back and 5.2 lay with 2% commission you lock in £7.57, or 75.7%.
Why use higher odds for a free bet?
Because the stake isn’t returned, it’s a smaller share of what you lose at higher odds. A £10 free bet laid at 2.0/2.04 keeps £4.85 (48.5%). At 6.0/6.2 it keeps £7.93 (79.3%). Go too high, though, and the gap between back and lay prices usually widens and the liability gets big.
What is a good free bet retention?
About 70–80% of the free bet’s value is a typical target for stake-not-returned free bets. Lewis aimed for around 80% on reloads.
What does stake returned (SR) change?
An SR free bet pays the stake back with the winnings, so it is worth more and you lay more: lay stake = free bet × back odds ÷ (lay odds − commission). They are rare in the UK.
Do I need an exchange account to lock in a free bet?
Yes. You lay the same selection at a betting exchange such as Betfair Exchange, Smarkets or Matchbook. Make sure your exchange balance covers the liability before you place the lay.
Are free bet winnings taxed in the UK?
No. Gambling winnings are not subject to income tax in the UK, and that includes profits from matched betting.
What do underlay and overlay mean?
Laying less (underlay) or more (overlay) than the balanced amount. Underlaying a free bet means you make more if the bookie bet wins and less if it loses. The slider shows both outcomes so you can see exactly what you are trading.
Lewis's take
I started in 2017 off the back of a MoneySavingExpert article, and made about £1,000 in my first four weeks on sign-up offers: Betfred, Coral, Ladbrokes, Bet365. Every penny of that was free bets turned into cash exactly like this. On reloads I aimed to keep about 80% of each free bet. People hear "betting" and switch off, but this bit is pure maths using sign-up bonuses.
Where next
- Matched betting calculator: qualifying bets, refunds and the lay maths for every offer type.
- OddsMonkey review: whether the paid oddsmatcher is worth it.
- Coming soon: each way and extra place calculator, dutching calculator, and a matched betting spreadsheet.
Update log
- Calculator launched. Formulas tested against worked examples at 0%, 2% and 5% commission.