4th Down Decision Calculator: Go for It, Kick, or Punt?

The 4th Down Calculator

The calculator opens on 4th-and-2 at the opponent's 40, the worked example below. The same model runs the 4th-down card on the tools page.

What It Computes

Each choice is scored from the offense's point of view. Points the opponent is expected to score on its next drive count as negative.

• Go for it = (conversion chance) × (expected points of a new 1st-and-10 at the line to gain) − (failure chance) × (the opponent's expected points taking over at the spot). A conversion that reaches the goal line is scored as a touchdown, worth 6.95 points in the model.
• Field goal = (make chance) × 3 − (miss chance) × (the opponent's expected points taking over at the spot of the kick, 7 yards behind the line, or its own 20 if that is better for it).
• Punt = −(the opponent's expected points after a 40-yard net punt, never worse for it than its own 20).

Three hand-set curves feed those formulas:

• Conversion chance depends only on the distance: 68% on 4th-and-1, falling by a factor of e^−0.085 for each extra yard (about 32% on 4th-and-10), kept between 2% and 95%.
• Field-goal chance is a logistic curve in the kick distance (yards to the goal line plus 17 for the end zone and the snap): 1 / (1 + e^{(distance − 56) / 6.5}). It is 50% at 56 yards, and a try longer than 68 yards counts as 0%.
• Expected points of a 1st-and-10 run in straight lines through five anchors: −0.6 at your own goal line, +0.6 at your own 20, +2.0 at midfield, +4.2 at the opponent's 20 and +6.4 at the opponent's 1.

The two inputs are the yards to go (1–30) and the yard line, entered as a side of the field plus a number. Internally the model measures from the offense's own goal line, so "opponent's 40" is 60.

Worked Example: 4th-and-2 at the Opponent's 40

The calculator returns go for it +1.22, field goal +0.38 and punt −0.60 expected points, so it recommends going for it. Step by step:

• Go: the conversion chance on 4th-and-2 is 0.68 × e^−0.085 = 62.5%. A conversion gives a 1st-and-10 at the opponent's 38, worth 2.88 points. A failure hands the opponent the ball at its own 40, worth 1.53 points to it. 0.625 × 2.88 − 0.375 × 1.53 = 1.80 − 0.58 = +1.22.
• Field goal: the try is 40 + 17 = 57 yards, made 46.2% of the time. A miss gives the opponent the ball at its own 47, worth 1.86 points to it. 0.462 × 3 − 0.538 × 1.86 = 1.38 − 1.00 = +0.38.
• Punt: a 40-yard net punt from the opponent's 40 reaches the end zone, so the opponent starts at its own 20, worth 0.60 points to it: −0.60.

Distance moves the call. From the same spot, only the go value changes:

Every value in this section is the output of the calculator above, run with these inputs.

Limits

• The curves are hand-set, not fitted. They follow the shape of published expected-points work, but the site's game-level dataset cannot fit a real expected-points model, so none is claimed. Treat close calls (a gap of a few tenths of a point) as close.
• No score or clock. Expected points ignore the game state. Late in a close game the right call is the one that raises win probability, which can differ; see the win probability calculator.
• No team, kicker or weather. Every offense converts at the same rate and every kicker has the same range.
• Fixed punt and fixed conversion spot. Every punt nets 40 yards, and a conversion is credited as a 1st-and-10 exactly at the line to gain.

If you want to plug in your own conversion rate, kick rate and expected-points values, the assumptions version on the calculators page takes them as inputs.

Further Reading

• The Fourth-Down Revolution: What the Analytics Actually Say
• Expected Points (EP) and EPA, the scale every value above is on
• Special Teams Analytics, on kicking and punting value
• Chapter 22: Fourth Down Decision Making, the code-first version
• NFL Win Probability Calculator
• All NFL calculators