Age Grading Calculator

What does this calculator do?

The age-grading calculator multiplies a finish time by an age factor to produce an open-class (20–29) equivalent time. A 45-year-old 50:00 10K becomes a faster equivalent so you can compare it with younger performances, or with yourself at a different age.

The method type is Endurometry approximation. These numbers are not an official World Masters Athletics (WMA) result. WMA publishes separate factor tables by sex and by event. This page uses one simplified road-style curve for every distance and both sexes. Do not use it for records, rankings, championships or prize eligibility.

How does it work?

The factor is 1.0000 from age 20 through 25 (open class). From 30 to 90 the factor falls in 5-year knots; ages between knots are linear interpolations. Graded time = finish time × factor. Because masters factors are below 1, the equivalent time is faster than the clock — that is the point of the conversion, not a claim that you ran faster.

The distance box only computes the displayed average pace. It does not choose a different table: 5K, marathon and everything in between share the same knots. Official WMA grading is event-specific and sex-specific; this page is not.

Formula

graded time = finish time × f(age)

Endurometry knots (same table, all events, men and women)
  20–25  1.0000     50  0.9259     75  0.7396
  30     0.9930     55  0.8986     80  0.6896
  35     0.9822     60  0.8665     85  0.6378
  40     0.9676     65  0.8292     90  0.5848
  45     0.9490     70  0.7866

Between knots: linear interpolation
  f = f0 + (age − a0) / (a1 − a0) × (f1 − f0)

Factors are shown to four decimals. Times are rounded to the nearest second only when displayed. Ages outside 20–90, and paces faster than 1:00/km or slower than 2:00:00/km, are rejected rather than silently clamped on this page.

Worked example

How to interpret the result

Read the large figure as “what this performance would look like on an open-class clock, according to Endurometry’s curve.” It is a conversation aid — tracking yourself year to year, or stacking club-mates of different ages — not a ranking score. This page does not compute an age-grade percentage against a world standard; that is a different WMA product.

If two calculators disagree by tens of seconds, believe the official WMA / Howard Grubb tables when the use case is competition. For a race-time scaling to another distance, use the race time predictor, which is a published model, not this approximation.

Assumptions and limitations

Assumptions

• The factor depends only on age. Sex, event, surface and the year of the WMA table are ignored.
• Open class is ages 20–29 (factor 1.0000 through the 25-year knot).
• The finish time is a genuine race effort on the selected distance; the distance does not change the factor.

Limitations

• Not official WMA. Endurometry does not copy, license or reproduce World Masters Athletics factor tables. Results must not be presented as WMA age grades.
• One table for men and women. Official WMA publishes separate male and female factors; mixing them here is a simplification, not equality of physiology.
• One table for every distance. Official grading uses different standards for 5K, 10K, half, marathon and track events.
• 5-year knots with straight lines between them. Real WMA tables are finer and are revised; ours are not.
• No age-grade % (performance vs world record). Only time × factor is shown.
• Ages outside 20–90, or a pace outside 1:00–2:00:00 per km, are rejected.

Methodology and sources

Method type: Endurometry approximation

This calculator is an Endurometry approximation: a single road-style age-factor curve with 5-year knots and linear interpolation, shared by all distances and both sexes. It is not an implementation of official WMA tables and must not be read as an official WMA result.

• Methodology: Age grading (Endurometry approximation)
• Methodology: Rounding and displayed precision

Sources: Endurometry age factors

Last reviewed: October 5, 2026