Calculate football win probability from the score, time left, possession, field position and point spread, with fair moneyline odds and the lead you need.

Sets the spread of final margins used by the model: 13.45 points for the NFL, 16.5 for college.

Yard line 1 to 50 as marked on the field. Left blank it assumes the ball is on the offense’s own 25.

Negative if your team was favored, positive if an underdog. Leave blank for an even matchup.

+ Advanced: down and distance

Football Win Probability Formula

This calculator uses a transparent American-football scoring-margin model. It does not use soccer expected goals or a Poisson goal model. The primary assumption is that the final score margin can be approximated by a normal distribution whose mean changes with the game state.

Pregame Model

When the point spread is entered from your team’s perspective, the model converts that spread to an expected final margin. A team listed at -3.5 is treated as having an expected margin of +3.5 points. The full-game scoring-margin standard deviation is 13.45 points for the NFL setting and 16.5 points for the college setting.

Expected Margin = - Point Spread
Final Margin sim Normal(Expected Margin, Standard Deviation)

Regulation ties are counted as half a win. The result therefore adds the probability of a margin above +0.5 to half the probability between -0.5 and +0.5.

Live Game Model

Live mode starts with the current score margin. It then adds a bounded expected-points estimate for the current drive and the remaining share of the pregame expectation. The amount of future scoring uncertainty decreases with the square root of the fraction of regulation time remaining.

Time Fraction = racSeconds Remaining3600
Live Mean = Current Margin + Possession Sign imes Drive EP - Spread imes Time Fraction
Live SD = Full Game SD imes sqrtTime Fraction

The drive estimate uses field position, down, distance, and expected seconds remaining in the drive. It is capped between -1.6 and 6.6 points and is intentionally a compact heuristic rather than a play-by-play model.

Lead Needed for a Target Probability

Target mode reverses the same normal-margin calculation. It finds the score margin that produces the selected win probability at the chosen time, assuming neutral possession and evenly matched teams. The whole-number lead is rounded up when a positive lead is required.

How to Use the Result

  • Use live mode for score, clock, possession, field position, down, and distance.
  • Use pregame mode to convert a point spread, rating edge, or American moneyline into an estimated fair win probability.
  • Use target mode to estimate the lead associated with a selected win probability and time remaining.

Assumptions and Limitations

  • The model is an estimate and is not trained separately for every team, season, weather condition, or injury situation.
  • It does not explicitly model timeouts, two-minute clock strategy, overtime rules, turnover likelihood, fourth-down choices, or team-specific pace.
  • Point spreads and moneylines may contain a sportsbook margin. The no-vig option can remove a two-sided market margin when both prices are entered.
  • Small input changes late in a game can produce large probability changes because little scoring uncertainty remains.

Browse the complete Football calculator collection or return to the Sports & Fitness Calculators hub.

Sources

Calculator Academy football win-probability model specification, version August 2026.