How much float does matched betting need?

The number people quote for matched betting is the bet size. The number that actually constrains you is the float — the total sitting across your bookmaker and exchange accounts, unavailable for anything else while positions are open. They're very different numbers, and the gap surprises almost everyone. A £20 free bet does not need £20 of float. It can easily need four times that. The reason is liability.

When you lay a selection on an exchange, you're taking the other side of the bet. If the selection wins, you pay out — and the exchange ringfences that potential payout the moment you place the lay. That ringfenced amount is your liability. Liability = lay stake × (lay odds − 1). The higher the odds, the bigger the liability relative to the stake. That matters enormously, because the standard advice is to use free bets at high odds — which is correct for extraction, and also exactly what makes the float requirement large.

Back £10 at 2.00 with the bookmaker. Lay at 2.04 on the exchange with 2% commission. Lay stake = back stake × back odds ÷ (lay odds − commission) = 10 × 2.00 ÷ 2.02 = £9.90. Liability = 9.90 × (2.04 − 1) = £10.30. So a £10 qualifying bet ties up £10 at the bookmaker and £10.30 at the exchange — roughly £20 for a £10 bet. Manageable.

Now the £20 free bet, stake not returned, at 5.00. Lay at 5.20, 2% commission. Lay stake = 20 × (5.00 − 1) ÷ (5.20 − 0.02) = 80 ÷ 5.18 = £15.44. Liability = 15.44 × (5.20 − 1) = £64.85. That's nearly £65 held at the exchange to extract a £20 free bet. The free bet costs you nothing at the bookmaker, but the exchange side is doing all the heavy lifting. This is why people who start with £50 stall almost immediately. They can place the qualifier and then can't cover the free bet that the qualifier was for.

With a couple of hundred pounds you can work through offers one at a time, waiting for each to settle before starting the next. It works; it's just slow, and slow matters because your accounts have a finite life. With five hundred to a thousand you can run several offers concurrently, which is where the time efficiency comes from — the same evening's work covers more offers. Below about £150 it becomes genuinely awkward: a single high-odds free bet can consume your entire exchange balance, and you spend more time waiting for settlement than doing anything. The rule that matters more than any figure: this must be money with no other job. Not the rent buffer, not money you'll need next month. Float that gets withdrawn mid-position is how covered bets turn into uncovered ones.

A practical problem nobody warns you about: your money drifts to the wrong side. Qualifying bets tend to lose slightly at the bookmaker and win slightly at the exchange, so over time the exchange balance grows while bookmaker balances shrink — and then you can't place the next back bet even though your total is unchanged. Expect to move money back periodically. Bank transfers to and from exchanges aren't instant, so factor that into your pacing rather than discovering it on a Saturday morning.