What is a back bet?
Back bet: A back bet is a wager FOR a selection to happen: the standard form of bet at any bookmaker, and one half of every matched bet you'll ever place.
When you walk into a high-street bookmaker, open the Bet365 app, or click the odds on a Sky Bet football market, every standard bet you place is a back bet. You are putting money on something to happen (Manchester United to win, a horse to come first, a tennis player to take the third set) at the odds the bookmaker has priced.
In matched betting, the back bet is one half of the structure. The other half is a lay bet at a betting exchange against the same selection. Sized correctly with our standard matched betting calculator, the two stakes leave you with roughly the same net result whichever way the event goes. That's the architecture every welcome offer extraction depends on, and the underlying technique is explained from scratch in our matched betting beginner guide.
Back bets pre-date matched betting by about a century. What's specific to matched betting is that the back leg is almost always placed at the bookmaker who's running the promotion, because that's where the value is being unlocked. The lay leg covers the downside.
Worked example
You bet £10 on Man Utd to win at 3.0 odds at Bet365 (a back bet). If Man Utd win, the bookmaker returns £30: your £10 stake plus £20 winnings. If they draw or lose, the £10 is gone.
On its own, that's an ordinary bet with ordinary variance. The matched-betting structure pairs this back bet with a £6.45 lay bet at 3.10 on Smarkets, which handles the "draw or lose" outcome. With both legs in place, the net result is roughly the same whichever side comes in, typically a small £0.20–£0.50 qualifying loss. The detail sits in our backing and laying guide.
Common mistake
Treating "back bet" and "qualifying bet" as the same thing. They overlap but they aren't identical. Every qualifying bet for a welcome offer is a back bet, but plenty of back bets are placed without any matched-betting context, like a casual bet on the Grand National in the pub. The back-bet concept is broader and older; the qualifying-bet concept is the matched-betting use of it.