Calculate a football passer’s completion percentage and next-pass scenarios, or find how many consecutive completions are needed to reach a target rate.
Football Completion Percentage Formula
Football pass completion percentage measures completed forward passes as a share of official pass attempts. The NCAA statistics manual states the calculation directly:
The calculator requires completions and attempts from the same scope, such as one quarterback in one game, a full season, or a team total.
What Counts in the Denominator?
Use the pass-attempt total in the official box score. Do not substitute dropbacks. Standard NFL passing tables list sacks separately from attempts, and an intercepted forward pass is an attempt but not a completion. Statistical rules can treat unusual plays differently, so official box-score totals are the safest inputs.
Next-Pass Scenarios
The primary result includes two useful one-play comparisons. A completed next pass produces:
An incomplete next pass leaves completions unchanged while attempts increase by one.
Consecutive Completions Needed for a Target
Target mode solves for the minimum number of added attempts that must all be completed. If n is that number and the target is written as a decimal, the inequality is:
The calculator represents the entered decimal target exactly and rounds the threshold up to a whole pass. If a defined current rate already meets the target, the answer is zero. With no attempts yet, the rate is undefined; one first completed pass defines a rate of 100 percent and meets any valid target, including zero. Once an attempt without a completion exists, an exact 100 percent cumulative rate cannot be restored with any finite number of later completions.
Example
A passer with 98 completions on 166 attempts has 68 incompletions. Dividing 98 by 166 and multiplying by 100 gives approximately 59.04 percent.
Interpretation and Limitations
- Completion percentage describes outcomes, not throw difficulty. NFL Next Gen Stats uses completion probability to add context that the basic box-score rate does not contain.
- Drops, throwaways, spikes, pressure, depth of target, and game situation are not separated by this formula.
- Small samples can move sharply after one attempt, which is why the calculator shows both next-pass scenarios.
- Target mode assumes every added pass is complete; it is a mathematical requirement, not a performance prediction.
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Sources
National Collegiate Athletic Association. Official NCAA Football Statisticians' Manual, current edition.
National Football League. NFL Player Passing Statistics and Next Gen Stats Glossary, current editions.
