Back To Lay Horse Racing System: How It Works & the Risks

Last updated: 4 October 2026

Back to lay is one of the best-known Betfair horse racing systems. You back a horse at a bigger price early, then lay it at a shorter price later. If the price shortens enough, you can lock in a profit whatever the result.

An earlier version of this page claimed the system could make £100+ a week. We have removed that claim. No betting system guarantees a profit, and this one loses money when your selections drift in the market. This guide explains how the method works, the rules we used, and the risks.

How back to lay works

Back early. Back a horse on the Betfair Exchange the evening before or the morning of the race.
Wait for the price to shorten. If money comes for the horse before the off, or it travels well in the race, its price shortens.
Lay at a shorter price. Lay the horse at the lower price. If you size the lay stake correctly, you make the same small profit whether the horse wins or loses. This is called “greening up”.

If the horse’s price drifts instead, you either leave the back bet running and take the result, or lay it at the bigger price and accept a small loss.

The selection rules

This is the version of the method we originally published. It aims to find horses likely to shorten in the market or race prominently.

Race type: flat races over a mile or further.
Experience: every runner in the race has run at least 3 times, so there is form to work with.
Market position: note the top two in the betting.
Running style: from those two, select a horse that likes to lead or race prominently.
Last run: it finished 1st or 2nd last time out, racing prominently.

Horses that lead or race close to the pace often trade at shorter prices in running than their starting price. That gives you a chance to lay them in-play, even if they don’t go on to win.

Staking and lay calculations

To lock in an equal profit, your lay stake is: back stake × back odds ÷ lay odds.

For example, you back a horse for £10 at 5.0. Later you lay it at 4.0. Your lay stake is £10 × 5.0 ÷ 4.0 = £12.50. Ignoring commission:

If it wins: +£40 on the back bet, −£37.50 on the lay = +£2.50
If it loses: −£10 on the back bet, +£12.50 on the lay = +£2.50

Betfair takes commission on your net winnings in each market, so your real profit is slightly lower.

The risks

Prices drift as often as they shorten. Each drift is a loss or a full-stake bet you didn’t want.
In-play trading is fast. Prices move in seconds, the live pictures you watch can be behind the market, and your lay bet may not be matched.
Commission and small margins mean you need a lot of successful trades to cover the losing ones.
Results from a few examples prove nothing. Test any system over many races, with small stakes, before you trust it.

Only use money you can afford to lose, and set deposit limits in your Betfair account before you start.