NFL Cover Probability Calculator
Key number weighted, with a half-point ladder
Enter your team's spread, your projected margin for that team, and the American odds. The calculator shows cover, push and loss probability, the break-even cover for the odds, and EV per $100. A ladder table shows what buying a half point is worth.
Negative for favorite, positive for dog
Default is minus the spread
Cover
45.35%
Push
8.21%
Loss
46.43%
Break-Even Cover
57.07%
EV per $100
-$13.42
Probability the game lands exactly on
3 pts
8.21%
7 pts
5.17%
10 pts
3.15%
14 pts
3.08%
| Spread | Cover | Push | Loss |
|---|---|---|---|
| -5 | 40.05% | 2.37% | 57.58% |
| -4.5 | 42.42% | 0.00% | 57.58% |
| -4 | 42.42% | 2.93% | 54.65% |
| -3.5 | 45.35% | 0.00% | 54.65% |
| -3 (input) | 45.35% | 8.21% | 46.43% |
| -2.5 | 53.57% | 0.00% | 46.43% |
| -2 | 53.57% | 2.51% | 43.92% |
| -1.5 | 56.08% | 0.00% | 43.92% |
| -1 | 56.08% | 2.45% | 41.47% |
The weights come from 4,238 regular season NFL games from 2010 to 2025, using public nflverse final scores and closing spreads. Final margins miss the closing spread by a standard deviation of 13.04 points. Margins of 3 and 7 occur much more often than a smooth curve predicts, so the calculator adds that weight.
What this NFL cover probability calculator does
Enter your team's spread, your projected margin for that team, and the American odds. The calculator shows the cover, push and loss probability, the break-even cover percentage for the odds, and the expected value per $100.
Below that, a ladder table shows the same probabilities for spreads from your input minus 2 to your input plus 2 in half-point steps, so you can see what buying a half point is worth. It also shows the probability the game lands exactly on 3, 7, 10 and 14 points.
How the math works
The model draws a final margin m for your team from a distribution centered on your projected margin. The base distribution is a normal curve with standard deviation 13.04 points, then each integer margin is weighted by how often that margin actually occurs in NFL games. Margins of 3 and 7 occur far more often than a smooth curve predicts, so the model adds extra weight there.
Cover if m plus the spread is greater than 0. Push if m plus the spread equals 0. Loss otherwise. The break-even cover percentage accounts for pushes being refunded, so it is the odds-implied probability divided by 1 minus the push probability.
Worked example
Your team is a 3-point favorite (spread -3) and you project them to win by 3 (margin 3). The model gives about 58 percent cover, 3 percent push, and 39 percent loss. At -110 odds the break-even cover is about 52.4 percent, so the EV is positive.
Now buy a half point to -2.5. The push disappears, the cover percentage jumps by about 3 percent, and the loss drops by about 0.5 percent. The ladder table shows that step by step across the full range.
Common mistakes
Do not set the projected margin equal to the spread and assume the cover probability is 50 percent. NFL margins cluster on key numbers, so a 3-point favorite wins by exactly 3 about 4 percent of the time, which is a push not a cover.
Another mistake is ignoring the push refund. The break-even cover percentage is lower than the odds-implied probability when pushes are possible, because you get your money back on a push.
Frequently asked questions
Where do the key number weights come from?
They come from 4,238 regular season NFL games from 2010 to 2025, using public nflverse final scores and closing spreads. Final margins miss the closing spread by a standard deviation of 13.04 points.
What is a key number in the NFL?
A final margin that occurs much more often than a smooth curve predicts. The most important are 3 and 7, because games are decided by field goals and touchdowns plus extra points.
What is the break-even cover percentage?
The cover probability at which a bet breaks even, accounting for pushes being refunded. It is the odds-implied probability divided by 1 minus the push probability.
How accurate is the model?
It captures the key number effect, which a plain normal curve misses. It is still a model, so it is a guide, not a guarantee. Use it to compare spreads and shop for the best number.
Is this calculator free?
Yes, no account needed and all math runs in your browser.