Market Making Calculator
One fair line plus a margin, and your two-sided quotes at every alternate spread.
| Spread | Fair % | Push % | Lay it | Take it |
|---|---|---|---|---|
| -9 | 30.6% | 1.9% | +214 | -260 |
| -8.5 | 31.9% | — | +201 | -243 |
| -8 | 32.6% | 2.2% | +195 | -234 |
| -7.5 | 34.1% | — | +182 | -218 |
| -7 | 35.8% | 4.6% | +169 | -201 |
| -6.5 | 38.8% | — | +148 | -175 |
| -6 | 39.9% | 2.9% | +141 | -166 |
| -5.5 | 41.7% | — | +131 | -154 |
| -5 | 42.6% | 2.1% | +126 | -148 |
| -4.5 | 43.8% | — | +120 | -141 |
| -4 | 44.9% | 2.6% | +114 | -134 |
| -3.5 | 46.4% | — | +107 | -126 |
| -3your line | 50.0% | 7.3% | -108 | -108 |
| -2.5 | 53.6% | — | -126 | +107 |
| -2 | 54.8% | 2.2% | -133 | +113 |
| -1.5 | 55.8% | — | -139 | +118 |
| -1 | 57.1% | 2.2% | -146 | +124 |
| -0.5 | 58.0% | — | -152 | +129 |
| 0 | 59.5% | 2.5% | -163 | +138 |
| +0.5 | 60.5% | — | -170 | +144 |
| +1 | 61.8% | 2.1% | -180 | +152 |
| +1.5 | 62.6% | — | -187 | +157 |
| +2 | 64.0% | 2.0% | -199 | +167 |
| +2.5 | 64.7% | — | -206 | +172 |
| +3 | 69.2% | 6.5% | -257 | +212 |
"Lay it" is your price on the favorite side of that number, "take it" is your price on the underdog side. The pair carries the width you set, so at 4% the two quoted probabilities add to about 104%. Notice how much the price moves across a key number compared with an ordinary one: that gap is the whole reason alternate lines are not evenly spaced.
Advanced: model assumptions+
These are the two inputs the model actually runs on, and you can change them. Sigma is how far final margins scatter around the line. The multipliers say how much more often each exact margin occurs than a smooth curve would predict, which is what makes 3 and 7 expensive in football. Edits are saved in your browser and shared across every calculator that uses this model, so your tuned key numbers follow you.
1.00 means no clustering at that margin. Anything above 1 means the number lands more often than a smooth curve predicts, so a half point across it costs more.
Enter one spread, the fair odds you believe belong on it, and the total margin you want to run. The calculator returns the two-sided prices to post at every alternate half point, holding your margin constant while the prices move with the real probability of each number.
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How the Market Making Calculator works
How the ladder is built
Your spread and fair odds define a view: at that number, this side covers this often. The calculator finds the margin distribution consistent with that view, reads the cover probability at every other half point, then adds your margin evenly across the two sides. Every rung comes from the same opinion, so the whole board is internally consistent.
Margin is the lever you control
Width, or margin, is the total overround across both sides of your quote. At a 4.5% margin the two prices you post imply about 104.5% between them, and that is your theoretical hold. Tighter attracts more volume with less cushion; wider does the reverse. Set it once and every rung inherits it.
Why the prices move unevenly
Because football results cluster on 3 and 7, the two-sided price shifts far more when you move across those numbers than across an ordinary one. A maker who prices 3 to 3.5 as a small, even move gets picked off on the most common margin in the sport. This calculator moves the price by the real probability, so your key numbers are protected.
Pushes and whole numbers
On a whole number there is a real chance of landing exactly on it, a push rather than a win or loss. The percentages here are conditional on the bet resolving, and the push column shows how much outcome space is set aside, which is why a whole number prices so differently from the half points beside it.
A worked quote ladder around -3
An NFL favorite fair at -3, quoted at a 4.5% margin. Read down the two price columns and watch what happens either side of 3: the step from -3.5 to -2.5 moves the price far more than the step from -6.5 to -5.5. That is the key-number effect a maker must price in, or get picked off on the most common margin in the sport.
| Spread | Fair % | Push % | Lay it | Take it |
|---|---|---|---|---|
| -6 | 39.9% | 2.9% | +140 | -169 |
| -5.5 | 41.7% | — | +130 | -156 |
| -5 | 42.6% | 2.1% | +125 | -150 |
| -4.5 | 43.8% | — | +119 | -143 |
| -4 | 44.9% | 2.6% | +113 | -136 |
| -3.5 | 46.4% | — | +106 | -128 |
| -3 | 50.0% | 7.3% | -109 | -109 |
| -2.5 | 53.6% | — | -128 | +106 |
| -2 | 54.8% | 2.2% | -134 | +112 |
| -1.5 | 55.8% | — | -140 | +117 |
| -1 | 57.1% | 2.2% | -148 | +123 |
| -0.5 | 58.0% | — | -154 | +128 |
| 0 | 59.5% | 2.5% | -165 | +136 |
How this is modeled. Margins are treated as a normal distribution around your line, reweighted by how often each exact margin occurs, using the same per-league key numbers as the compare lines calculator. Tune those key numbers in the advanced panel and the change follows you across every calculator.
Taking prices instead of setting them? The alternate lines calculator strips margin out and shows fair value, so you can judge whether a book's alternate line is worth taking.
Frequently asked questions
What is a market making calculator?+
It turns one fair reference line into a full set of two-sided quotes. You supply a spread, the fair odds you think belong on it, and the margin you want to run, and it returns the prices to post at every alternate half point.
How do you set two-sided betting lines?+
Start from a fair probability for the main number, read the fair probability at each alternate number from a margin distribution, then add your chosen margin evenly across both sides. This calculator does all three steps and holds the margin constant across the ladder.
What is a good market width?+
It depends on the volume you want and the risk you will carry. Retail books commonly run 4 to 5% on a standard spread. Tighter than that attracts more action with less cushion for being wrong.
How is this different from the alternate lines calculator?+
The market making calculator adds your margin and outputs the prices you would post. The alternate lines calculator strips margin out and shows fair value, for a bettor deciding whether a book's number is worth taking.
When should I use a market making calculator?+
Use it when you are the one setting prices, whether posting lines on a peer-to-peer exchange or pricing a private pool, and you want a consistent two-sided ladder from a single fair opinion.