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What is overlaying and underlaying in matched betting?

Overlaying and underlaying are terms used to describe a different style of laying matched bets. We lay slightly more (overlaying) or slightly less (underlaying) to ensure a risk-free matched bet.

Use Trickybet advanced calculator to calculate standard matched bet lay stakes, overlays and underlays.

What is overlaying?

Overlaying is laying more than a standard amount at a betting exchange.

By overlaying you win more money at the exchange if your lay bet wins, but make less profit if your back bet wins at the bookmaker.

Overlaying example

You can use overlaying for free bet on winner horse racing offers.

Let’s imagine you bet £10 on a horse at 5/1 (6.00) for Betfair Sportsbook 3/1+ SP winner offer.

Your horse is 6.00 to lay at Smarkets.

The standard lay stake is £10.03 (at 2% exchange commission) for 17p qualifying loss. Alternatively, lay £10.20 (overlaying) on Smarkets to make this offer risk-free.

  • If your horse wins: The overlay gives a £1 qualifying loss, but with a £10 free bet to come.
  • If your horse loses: there is no free bet due. However, the overlay ensures £0 qualifying loss. Your £10.20 lay covered the exchange commission on the winning lay bet.

A standard lay would give a qualifying loss. So, overlaying is used to eliminate risk when matched betting.

What is underlaying?

Underlaying is laying less than the standard amount. We aim to make the offer risk-free.

  • If your back bet wins – you get more profit.
  • If your back bet loses – your profit is less than a standard matched bet.

We can underlay risk-free bet offers, i.e. refund as a free bet if your first bet loses. The underlay ensures these offers are 100% risk-free.

Underlaying a free bet refund offer

For example, £10 risk-free on a selection that’s 3.00 to back and 3.10 to lay.

Standard lay: a standard lay of £9.74 = £0.45 loss and the offer isn’t risk-free.

Underlay: an underlay of £ 9.52 gives zero loss if win, or £0.67 loss if doesn’t win.

You only receive a free bet if your selection loses, so underlay to break even if win or make a small loss (-£0.67) if lose but with a £10 free bet to come.

Assuming the £10 free bet is converted in to £8 profit, the risk-free net profit is around £7.

Underlaying a free bet

Matched bettors often underlay Stake Not Returned (SNR) free bets. Underlaying is a good technique when using free bets at high odds.

Imagine using a £10 free bet on a 10.00/10.00 odds match. You can lay £7 at the exchange (2% commission).

  • If the free bet wins you are £27 up (£90 win minus £63 lay loss).
  • If the free bet loses £6.86 is the profit.

You are laying less to make extra profit if your high odds selection wins, whilst sacrificing a small portion of your free bet.

Underlaying for bonus offers

Another use of underlaying is for bonus rollover offers. You would underlay to try to lose your bookmaker balance in to the exchange.

Otherwise, if the back bet wins there is enough money at the bookie to complete the wagering requirement.

Underlaying arbitrage bets

Underlaying is also useful when matched betting in shops – or sharbing.

Find an arbitrage bet on a shop betting coupon, simply lay your stake plus commission for a risk-free shot at sharbing profit.

Check out the sharbing guide for some examples of underlaying.