Alternate Lines Calculator
Check whether a book's alternate spread or total is actually fair value.
| Alt spread | Fair (favorite) | Fair (underdog) | Push |
|---|---|---|---|
| -9 | +206 | -206 | 2.0% |
| -8.5 | +194 | -194 | — |
| -8 | +188 | -188 | 2.3% |
| -7.5 | +176 | -176 | — |
| -7 | +163 | -163 | 4.7% |
| -6.5 | +144 | -144 | — |
| -6 | +137 | -137 | 3.0% |
| -5.5 | +128 | -128 | — |
| -5 | +123 | -123 | 2.1% |
| -4.5 | +118 | -118 | — |
| -4 | +112 | -112 | 2.6% |
| -3.5 | +106 | -106 | — |
| -3main line | -110 | +110 | 7.3% |
| -2.5 | -126 | +126 | — |
| -2 | -133 | +133 | 2.2% |
| -1.5 | -138 | +138 | — |
| -1 | -146 | +146 | 2.2% |
| -0.5 | -151 | +151 | — |
| 0 | -161 | +161 | 2.5% |
| +0.5 | -168 | +168 | — |
| +1 | -178 | +178 | 2.1% |
| +1.5 | -184 | +184 | — |
| +2 | -195 | +195 | 2.0% |
| +2.5 | -201 | +201 | — |
| +3 | -248 | +248 | 6.3% |
These are the fair, no-vig prices at each alternate number. A book's price is worth taking only when it pays more than the fair number for the side you want.
Good value — take it.
Fair price on the favorite at -6.5 is +144, and the book is offering +180. That is worth +$14.58 per $100 (+36 cents vs fair).
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 the main line and the vig-free odds it should carry, and the calculator shows the fair price at every alternate spread around it. Then drop in the price a book is offering on any alternate number to see whether it is good value or a trap.
Done with the math? Bet a real market.
These numbers are live on the BettorEdge marketplace right now, at prices set by bettors, not the house.
Related tools
Now get these prices for real.
The math is free. Better odds are on BettorEdge. Sign up for a shot at up to $100. No deposit needed.
How the Alternate Lines Calculator works
What this tells you
Books offer a ladder of alternate spreads and totals, each at its own price, and most of those prices are worse than fair once you account for the margin. This calculator strips that away: from one fair reference line it derives the true, no-vig price at every alternate number, so you can tell a genuine bargain from a number dressed up to look like one.
Fair value versus a book's price
The fair odds here carry no margin. A book's offered alternate line almost always does, so comparing the two directly shows you exactly how much juice you are being charged for that number. When a book's price is better than fair, which happens on stale or promo lines, that is the alternate line worth taking.
Why the rungs are not evenly spaced
Football margins pile up on 3 and 7, so the fair price gap between -2.5 and -3.5 is far larger than between -10.5 and -11.5. A calculator built on a smooth curve would misprice exactly the numbers that matter most. This one carries the same key-number clustering used by the compare lines calculator.
Alt lines versus market making
This tool is for a bettor deciding whether to take a number. If instead you are the one setting prices, the market making calculator does the reverse job: you supply a fair line and a margin, and it returns the two-sided quotes to post at every alternate spread.
Fair alternate prices off a -3 line
An NFL favorite fair at -3, shown as the vig-free price at every alternate number. These are what each alternate is actually worth, with no margin. Compare a book's offer against the matching row: if the book pays more, it is value; if it pays less, you are buying juice.
| Alt spread | Fair (favorite) | Fair (underdog) |
|---|---|---|
| -7 | +180 | -180 |
| -6.5 | +158 | -158 |
| -6 | +150 | -150 |
| -5.5 | +140 | -140 |
| -5 | +135 | -135 |
| -4.5 | +129 | -129 |
| -4 | +123 | -123 |
| -3.5 | +116 | -116 |
| -3 | -100 | -100 |
| -2.5 | -116 | +116 |
| -2 | -121 | +121 |
| -1.5 | -126 | +126 |
| -1 | -133 | +133 |
| -0.5 | -138 | +138 |
| 0 | -147 | +147 |
| +0.5 | -153 | +153 |
| +1 | -162 | +162 |
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. The NFL weights come from the published 2000-2025 margin distribution. Treat the fair prices as a well-grounded reference, not an exact market number.
Setting prices instead of taking them? The market making calculator adds your margin and outputs the two-sided lines to post. To value a single half point, use the half point calculator.
Frequently asked questions
What is an alternate lines calculator?+
It shows the fair, vig-free price at every alternate spread or total around a main line, so you can judge whether a book's offered alternate line is good value or overpriced.
How do I know if an alternate line is worth it?+
Compare the book's offered price against the fair price for that number. If the book pays more than fair, it is value; if it pays less, you are being charged extra juice for the alternate. Enter both above to see the exact gap.
Why do fair prices jump so much around 3 in the NFL?+
Because roughly one NFL game in seven ends with a 3-point margin. Moving across 3 shifts far more probability than moving across a number where results rarely land, so the fair price moves much further there.
What is the difference between the alternate lines and market making calculators?+
The alternate lines calculator is for a bettor judging a book's price and shows fair, no-vig odds. The market making calculator is for someone setting prices and adds a chosen margin to output the two-sided lines to post.
When should I use the alternate lines calculator?+
Use it when a book offers a spread or total at a number other than the main line and you want to know if the price is fair before taking it.