- Maths reviewed by Josh Miller
- Tested by Diana Westfield
The exchange trading calculator works out the stake that turns an open position into a fixed profit, which traders call greening up. You backed a horse at 5.0, it’s now 4.0, and you want £2.50 on every outcome instead of a bigger win or nothing. Lay £12.50 at 4.0 and that’s what you get. The same tool handles lay the draw in football and lay the field in racing.
Green up calculator: backing high, laying low
A green up is just the hedge maths from the lay calculator, done in the middle of a trade. The stake you lay is the back stake times the back odds, divided by the lay odds. Work through a typical pre-race move:
| Step | Back £10 at 5.0, lay at 4.0 |
|---|---|
| Lay stake | £10 × 5.0 ÷ 4.0 = £12.50 |
| If the horse wins | +£40 on the back, −£37.50 on the lay = +£2.50 |
| If it loses | −£10 on the back, +£12.50 on the lay = +£2.50 |
| After 2% commission | £2.45 |
The same move works in reverse. Lay first at 4.0, back later at 5.0, and you’re green as well. If the price goes the wrong way, greening up spreads the loss evenly instead, which many traders still do rather than let one result decide everything.
Lay the draw
Lay the draw is the best-known football trading idea, and it now has its own lay the draw calculator with the exit stake worked out. Before kick-off you lay the draw at around 3.4. A goal goes in, the draw drifts to 5.5 or so, and you back it to lock in profit. With a £20 lay at 3.4 that means backing £12.36 at 5.5, and you’re about £7.60 up whatever the final score.
The catch is the 0-0. If nobody scores, the draw price falls minute by minute, and by the 70th minute it might be 2.0. Get out then and you lose roughly a third of your liability; hold to the end and you lose all £48. That’s why people only run it on matches they expect to be open, and why a goal-scoring model like the Poisson calculator is a sensible first check. A drawn game is roughly one match in four in most leagues.
Lay the field calculator
In racing, lay the field means laying every runner at the same low in-running price, say 3.0. Most races have one or two horses that hit 3.0 at some stage, often a front-runner that then fades. Each matched lay on a loser wins you the stake, and the winner’s lay costs stake × (price − 1). At 3.0 you need three matched lays, the winner and two others, just to break even; every one beyond that is profit. If only the winner is matched you lose £10 on a £5 stake, which is the worst case shown above.
Commission and the small margins
Trading profits are small per market, so commission matters more here than on ordinary betting. Two percent of a £2.50 green is only 5p, but across hundreds of trades it adds up, and the 5% standard rate at the biggest exchange takes a real bite. Set your own rate in the CasinoCalcs calculator. For pre-match hedges against a bookmaker bet rather than an exchange back, the hedge calculator is the better fit, and the matched betting calculator covers free bets.
Trading feels like skill when it works and like chasing when it doesn’t. BeGambleAware.org has free help if it starts to feel like the second one.