This page is about converting a free bet you already hold. If you are still deciding which offers to claim, start with how bookmakers’ free bets work.
Short version: a free bet is never worth its face value. How much of it you actually keep depends on two things — whether the stake comes back, and what odds you place it at. Get both right and a £20 free bet is worth around £19. Get them wrong and the same £20 free bet is worth £6. That gap is the single largest controllable variable in matched betting, and it is the reason this page exists.
Why a free bet is not worth its face value
You cannot withdraw a free bet. You have to place it, and the outcome is uncertain, so to turn it into money you lay the same selection on an exchange. Whichever way the event goes, you end up with a known amount — but that amount is less than the free bet’s face value, because the exchange keeps a slice and because the two prices never match perfectly.
The percentage you keep is called retention. It is the number that matters, and it varies enormously.
Stake not returned (SNR)
The common type, and the one where odds matter. If your £10 SNR free bet wins at odds of 4.0, you receive £30 — the winnings only. The £10 stake is never paid back, because it was never your money.
That single fact drives everything. At odds of 1.5 an SNR free bet returns £5 on a £10 stake; at 10.0 it returns £90. The higher the odds, the larger the proportion of the bet’s value that sits in the winnings rather than in the stake you are not getting back.
A worked example
A £20 SNR free bet, backed at 5.0, laid at 5.2, with 2% commission.
lay stake = free bet × (back odds − 1) ÷ (lay odds − commission) = 20 × 4 ÷ 5.18 = £15.44
liability = 15.44 × 4.2 = £64.85
| Outcome | Bookmaker | Exchange | Net |
|---|---|---|---|
| Selection wins | +£80.00 (winnings only) | −£64.85 | £15.15 |
| Selection loses | £0 | +£15.13 after commission | £15.13 |
About £15.14 either way, from a £20 free bet. Retention roughly 76%. Note the liability: £64.85 tied up to extract £15. That is normal, and it is why exchange balance is the constraint on how many offers you can run at once.
Stake returned (SR)
Rarer and considerably better. A £20 SR free bet backed at 3.0 pays £60 if it wins — stake included, exactly as though you had bet your own money. Because it behaves like cash, you lay it exactly as you would a qualifying bet.
The same £20, backed at 3.0 and laid at 3.05 with 2% commission, needs a lay stake of £19.80 and returns about £19.40 whichever way it goes. Retention around 97%.
And because the stake comes back, high odds bring no advantage. You simply want the tightest back/lay match you can find, which is usually at short odds on a liquid market. If you are ever offered a choice, an SR free bet is worth roughly a quarter more than an SNR one of the same face value.
The mistake that costs the most
Placing an SNR free bet at short odds.
It feels safer — short odds mean the selection probably wins — but that instinct is exactly backwards. You are not gambling; you have laid the bet off. The only thing short odds achieve is shrinking the winnings, which is the only part of an SNR free bet you get to keep.
A £20 SNR free bet at 1.5 retains around 30%, or £6. The same free bet at 5.0 retains around 76%, or £15. Same offer, same effort, nine pounds different. Across fifty welcome offers that habit is the difference between a few hundred pounds and most of a thousand.
Bonus funds and wagering requirements
Some “free bets” are not free bets at all. Bonus funds land in your balance but cannot be withdrawn until they have been staked a set number of times — a 35x requirement on a £10 bonus means staking £350 in total.
Treat these as a series of qualifying bets. Each one costs a small amount to lay, and the total of those small costs is what the bonus really costs you to unlock. Work it out before you start: multiply the wagering requirement by a realistic per-bet qualifying loss and compare it to the bonus value.
Many casino bonuses fail that test. Some sportsbook ones fail it badly. “Free” in the marketing does not mean free in the arithmetic.
Quick reference
| Type | Ideal odds | Typical retention | Calculator mode |
|---|---|---|---|
| Stake not returned | 4.0 to 8.0 | 75% to 85% | Free bet (SNR) |
| Stake returned | Any, closest match | 90% to 98% | Free bet (SR) |
| Bonus with wagering | Low odds, tight match | Varies widely, often poor | Qualifying bet (repeat) |
Why not simply use the highest odds available on an SNR free bet? Because the back/lay gap widens as odds lengthen, and beyond about 8.0 the worsening match eats the gain. The sweet spot is high enough to keep the winnings large, low enough that the two prices still sit close together.
Terms worth reading before you place
- Minimum odds. Usually on the qualifying bet, sometimes on the free bet too. Miss it and the offer does not trigger.
- Expiry. Often seven days, sometimes 48 hours. An expired free bet is worth nothing at all.
- Whether it can be split. Some free bets must be used in one go; others can be broken into smaller bets, which occasionally helps you find a better match.
- Excluded markets. Some offers bar certain sports, or bar each-way and bet builder bets.
Run everything through the matched betting calculator before placing — it has separate modes for SNR and SR, and picking the wrong one produces a confidently wrong lay stake. If the free bet has not arrived at all, see free bet not credited.
Frequently asked questions
How do I know whether a free bet is SNR or SR?
The terms will say, usually as “stake not returned” or “free bet stake not included in returns”. If the offer is silent, assume SNR — it is much the more common. You can also check the bet slip: it normally shows the potential return, and if that figure excludes the stake it is SNR.
Can I lose money on a free bet?
Only through error — laying the wrong selection, using the wrong calculator mode, or failing to get the lay matched. Laid correctly, a free bet produces the same profit whichever way the event goes.
Should I take a bigger free bet at worse terms?
Compare retention, not face value. A £50 free bet with 35x wagering can easily be worth less than a £20 SNR free bet you can lay in two minutes.
Worked figures are illustrative and use round numbers to show the mechanics; real odds, commission and offer terms vary. Some links on this site are affiliate links. 18+ only. Please gamble responsibly. BeGambleAware.org
