Race equivalent times — find your true performance potential
A single personal best never tells the whole story. When you enter several race times, patterns appear: maybe your 10K is world-class for your fitness while the marathon still lags — classic signs of incomplete endurance training, fuelling issues or simply fewer long efforts.
Why compare several distances?
Tables that map “level 62” from a 10K to a marathon assume your fitness is interchangeable across distances. Real runners specialise. Speed work lifts 5K/10K VO2 estimates; long aerobic volume lifts half and marathon estimates.
By computing effective VO2 max for each race (Daniels & Gilbert, 1979) you see which performances are currently “expensive” relative to your best day. That is more insightful than looking up one row in a static level chart.
Peak fitness is simply the highest effective VO2 among the distances you entered. Potential times assume you could race every distance at that same fitness — a useful ceiling, not a promise.
How the estimate works
Daniels & Gilbert model the oxygen cost of running speed and the fraction of VO2 max you can sustain for a given duration. Faster short races imply higher VO2; longer races at the same VO2 take proportionally longer.
Unlike world-record ratio tables that freeze men’s 2019 track records into 100 levels, our model updates continuously for any time you type. Elite ratios are a historical curiosity; your own recent races are a better training signal.
Use races from the last 6–8 weeks when possible. Course hills, heat and wind can inflate gaps that are not “fitness” problems.
How to read the gaps
Short distances lag. Often means missing speed or neuromuscular work — strides, intervals, and race-pace 5Ks — or that you simply have not raced short lately.
Marathon lags. Common for runners who train well for half marathons but undercook long runs, glycogen practice or weekly volume. A 5–15 minute gap vs peak is typical until the long-run engine catches up.
Even profile. When gaps stay under ~30–60 seconds (scaled by distance), you are well balanced. Keep the mix of easy volume and quality that got you there.
What to train next
If the marathon is the weak link, prioritise progressive long runs, marathon-pace segments and fuelling rehearsals — not more all-out 5Ks.
If the 5K/10K is soft versus your half, add threshold and VO2 intervals while protecting easy aerobic volume.
Pair this tool with our VO2 max calculator for training paces, and the event pace calculator when you pick a specific race with hills and weather.
FAQ
Is this the same as a “performance level” table?
Similar idea, deeper method. Level charts use fixed world-record ratios. We estimate VO2 from your actual times, so uneven profiles and intermediate times are handled continuously.
Which race should I trust most?
The one that produced the highest effective VO2 under fair conditions. That is your current peak fitness signal.
Can I project a first marathon from a 10K?
Yes — enter the 10K (and ideally a half). Treat the marathon potential as an optimistic ceiling until long-run training catches up.