Lay–to–back calculator
This calculator enables you to work out if you can achieve better odds for a particular selection by laying the other two selections in the right proportions. An explanation of this technique and instructions on using the calculator are given further down the page.
The calculator follows the '1X2' football betting convention: 1=Home win, X=Draw, 2=Away win. Book % should match the numbers you see on some exchanges and indicates the efficiency of the market (the closer to 100% the better. 'Best' is the improved book after lay–to–back calculations. Please read the information on the remainder of this page.
Using the calculator
The calculator is simple to use if you follow these steps:
- Copy the quoted betting exchange odds to the corresponding blue and pink cells
- Next to 1, 2 or X indicate what outcome you are looking to back (so the appropriate summary can be generated)
- Enter the amount you would stake if backing
- Click on 'Calculate'
- The green cells will show the odds achievable by laying for the corresponding selection
- If the odds in the green cell are better than for the blue cell in the same row as your selection:
- Read across the line for the selection you have chosen
- To the left and/or right of the green cell are the two amounts which you should lay against the selection indicated above it.
Example
When this page first loads, the blue and pink cells are pre–populated with sample odds and the stake is set to £10. If necessary click 'Reset', then click 'Calculate' and you will get a sample set of results.
Let's say you are planning on backing the home team to win (Selection 1) then we are comparing against the quote of 2.18 to back. Follow this row across and you will see that the green cell shows a value of 2.1935 – an improvement on 2.18. To achieve this improvement you will need to lay the other two outcomes – Away win (2) and Draw (X) – by the amounts shown below these selection in the same row.
So you would lay the Away win for £5.48 and at the same time lay the Draw for £6.45. This should be clear from the 'Summary' shown immediately below the table
Laying to back
It is sometimes possible to achieve better odds for backing a particular outcome by instead laying the other outcomes in the right proportions. This technique is only possible on the betting exchanges and works best when there are only two or three outcomes to an event, though it can occasionally work when there are four or five runners. The calculator above was designed for football match results and refers to Home Win, Away Win and Draw as 1, 2 and X respectively.
If we think about a football match, we might want to back the home team to win. However, if we think about this, backing the home team to win is the same as laying the away team and laying the draw, i.e. we are saying that (a) the away team will NOT win and (b) the match will NOT be a draw.
Several points to note when 'laying to back':
- You will not always get an improvement in odds in which case you're better backing as normal
- Occasionaly, especially in very active markets, you should be prepared that only one of the two lays gets matched, i.e. someone else lays before you do. To reduce this risk, 'refresh' the screen odds just before you submit the bets and if you do get caught, take action to avoid having a position you didn't intend to have. Before embarking on this type of betting you should become familiar with the workings of betting exchanges and the calculations necessary to take evasive action when required.
Further reading: Getting the best odds
About laying
The calculator is coded with the same colours as Betfair – blue for the odds offered for backing, pink for the odds available if you wan't to lay. When laying, it is worth remembering that the exposure and potential profit are not calculated in the same way as when you are backing. For example if you lay £10 that the home team will NOT win and the quoted odds to lay are 2.25, £10 is actually the backers stake and what you would stand to gain. Your potential downside is what the backer would stand to gain if the home team did actually win, i.e.£12.50.
If you want to think of lay odds in more regular terms use this formula:
regular_odds = 1 / (lay_odds – 1) + 1
Example: if the quote on laying Arsenal is 1.71, this means your odds of Arsenal NOT winning are:
1 / (1.71 – 1) + 1 = 2.41
Further reading: Betting exchanges
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