How age grading works in running
Age grading lets a 68-year-old and a 28-year-old compare performances fairly by adjusting for the slowdown that comes with age. It rests on a set of published age factors and a couple of simple formulas. Here is how the arithmetic works, why different websites disagree slightly, and what an age-grade percentage does — and does not — mean.
Open the Age Grading calculatorThe Age grading calculator applies the factors and formulas below to your time, age, sex and event, and returns your age-graded time and age-grade percentage.
The idea behind age grading
Age grading answers a simple question: how good is this performance for someone of this age and sex? It compares your time against an age standard — the time a hypothetical world-class athlete of your exact age and sex would run for the same event — and expresses the result as a percentage. That makes it possible to line up results across ages and events on a single, comparable scale.
The three formulas
Everything follows from an age factor: a number between 0 and 1 that captures how much a typical peak performance declines by your age for your event. From it, three relationships give you the outputs you need.
- actual time
- the time you actually ran for the event
- age factor
- the WMA factor for your sex, age and event (0–1)
- open standard
- the class world-best reference time for the event, independent of age
- age-graded time
- your time scaled to its open-class equivalent
- age standard
- the target time for your exact age and sex
The age-graded time restates your performance as if you had run it at peak age, so you can compare it against the open standard. The age-grade percentage then reads like a score: higher is better, with the open standard sitting at 100%. Broadly, above 60% is regional-class, above 70% national, above 80% world-class and above 90% approaching world-record territory — but treat those bands as rough signposts, not official cut-offs.
Why sites disagree: the table-year rule
The single most important thing to understand is §4.0: the factors come from World Masters Athletics age-grade factor tables that are identified by year. WMA revises these tables periodically as the pool of masters performances grows, and different calculators are built on different table years. Because a factor might shift from, say, 0.812 to 0.809 between editions, two reputable sites can report age-grade percentages that disagree by a few tenths of a percent for the identical performance.
Neither is “wrong” — they are using different editions of the same underlying method. For that reason we link to the official WMA publication rather than mirroring the whole table here, and we always state which table year a result is based on. If you are comparing two numbers, first check they came from the same table year.
What age grading does not tell you
Age grading tells you how a result ranks against an age-and-sex standard; it does not predict what you will run next, nor prescribe training. The factors are population statistics, so they describe the typical decline curve rather than your personal trajectory. Results also depend on the table year in force, and small differences in age rounding or event definitions between calculators can move the percentage by a fraction. Read an age-grade percentage as a fair comparison on a given day, using a stated table edition — not as a fixed truth about your ability.
Frequently asked questions
What is a good age-grade percentage?
As a rough guide, above 60% is regional-class, 70% national-class, 80% world-class and 90% approaching world-record standard. These are informal bands, not official thresholds.
Why does another site give me a different percentage?
Almost always because it uses a different WMA table year. The factors are revised periodically, so editions differ by tenths of a percent. Compare only numbers from the same table year.
Can age grading predict my next race?
No. It is a comparison of a performance against an age-and-sex standard, based on population statistics. For a forward-looking estimate, use a race-time predictor instead.
Related tools and reading
Age grading calculator
Enter time, age, sex and event to get your age-graded time and age-grade percentage.
ReadHow accurate is the Riegel race predictor?
For a forward-looking estimate rather than a comparison, see how race prediction works.
Sources
- World Masters Athletics, Age-Grade Factor Tables — the official age-grade factors, identified by table year; state the table year in force when reporting a result. Checked 23 Aug 2026.
- World Athletics, Competition and Technical Rules — event and course definitions underlying the open standards. Checked 23 Aug 2026.