Calculator · Training zones
Training Pace Calculator
Convert one race result into the five paces your week should actually be run at — easy, marathon, threshold, interval and repetition — using the Daniels and Gilbert VDOT model.
Recent race performance
Training zones
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Yasso 800s
Repeat target
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Why paces come from a race and not from a heart rate
Every training system needs an anchor: some measured quantity that says how fit you are right now. Heart rate can serve, but it drifts with heat, sleep, caffeine, stress and hydration, and maximum heart rate cannot be estimated from age with any useful precision. A recent race is a direct measurement of the thing you are actually trying to improve. It is the sturdiest anchor available to a runner without a laboratory.
The calculator takes that race and works backwards through two equations published by Jack Daniels and Jimmy Gilbert in 1979.
VO₂ = −4.60 + 0.182258v + 0.000104v²
Sustainable fraction of maximum over t minutes:
%max = 0.8 + 0.1894393·e^(−0.012778t) + 0.2989558·e^(−0.1932605t)
VDOT = VO₂ ÷ %max
The first equation says how much oxygen a given running speed demands. The second says what share of your ceiling you can hold for a given duration — high for a short race, decaying towards eighty percent as the race lengthens. Divide one by the other and you recover the ceiling itself. Then the calculator runs the process in reverse at each training intensity to produce a velocity, and converts velocity to pace.
What each zone is for
Easy, 62 to 72 percent
This is where adaptation happens, and it should occupy roughly eighty percent of your weekly minutes. The stimulus here is structural and metabolic: more capillaries feeding the working muscle, more mitochondria inside it, tougher tendons, a stronger left ventricle. None of that requires suffering, and all of it requires time on feet.
Marathon pace, 79 to 84 percent
Useful mainly to marathoners, where it rehearses the exact rhythm and fuelling of race day. For everyone else it sits in an awkward middle — too hard to be restorative, too easy to drive threshold adaptation. Use it deliberately or not at all.
Threshold, 86 to 88 percent
The highest intensity at which lactate production and clearance stay in balance. Training here raises the speed at which that balance tips, which is the single best predictor of distance race performance. The classic session is twenty minutes continuous, or cruise intervals of five minutes with one minute of jogging.
Interval, 97 to 100 percent
Work at or near the velocity that elicits your maximum oxygen uptake. Repeats of three to five minutes, because it takes about ninety seconds at this intensity just to reach maximum uptake — anything shorter and you finish before the stimulus properly starts.
Repetition, 105 to 110 percent
Not an aerobic session. Short, fast, fully recovered repeats that sharpen mechanics and neuromuscular recruitment. Two hundred to six hundred metres, with recovery long enough that each rep is fresh.
Reading the output honestly
The paces are ranges, not targets, and the range exists because your fitness is a moving thing and the day is a variable. On a warm afternoon, run the slow end. In cool conditions on rested legs, the fast end is available.
Polarised training research consistently finds that the runners who improve most run the great majority of their volume genuinely easy and the remainder genuinely hard, with very little in between. The failure mode for amateurs is a week composed entirely of moderate running: too taxing to recover from, too gentle to force adaptation.
Yasso 800s, and why they work better than they should
Bart Yasso, longtime race director at Runner’s World, noticed a coincidence: the time in minutes and seconds that a runner could hold for ten 800-metre repeats matched their marathon time in hours and minutes. Three minutes thirty per 800 predicted a 3:30 marathon.
There is no physiological mechanism that makes this true. It is a numerical accident that happens to land close for a wide band of runners, because 800 m at roughly 10K effort and marathon capability are both downstream of the same aerobic fitness.
What makes the session worth doing is not the prediction. Ten by 800 with equal-time recovery is a substantial aerobic workout in its own right, and building towards ten repeats across a training block is a clear, motivating progression. Treat the predictive claim as a rough sanity check and the session as the actual point.
Yasso tends to flatter runners with strong speed and modest endurance — precisely the group that struggles most in the last ten kilometres of a marathon. If your Yasso prediction is much faster than what the Riegel model gives from a recent half, trust Riegel.
Adjusting for conditions
The paces assume flat ground and cool weather. Hills and heat both raise the physiological cost of any given pace, sometimes dramatically. If you are training on a treadmill or on rolling terrain, the grade-adjusted pace calculator shows what a given incline is really costing you, and running by heart rate zone is the more reliable guide once the temperature climbs past about 20 °C.
If your race result is older than eight weeks, get a fresher number first — or estimate one with the race time predictor and treat the resulting paces as provisional.
Common questions
What does VDOT actually measure?
It is a performance-derived index, not a laboratory VO₂max. Jack Daniels and Jimmy Gilbert built it by combining the oxygen cost of running at a given velocity with the fraction of maximum oxygen uptake a runner can sustain for a given duration. Two runners with identical lab VO₂max values but different running economy will have different VDOTs, and the VDOT is the more useful of the two numbers because it reflects what you can actually do.
My easy pace looks embarrassingly slow. Is it wrong?
It is almost certainly right, and the discomfort you feel about it is the single most common reason amateur training plans fail. Easy running exists to build mitochondrial density and capillary networks and to let hard sessions be genuinely hard. Running it at threshold pace produces a permanently fatigued runner with no top end.
How often should I recalculate?
After any genuine race effort, and otherwise every six to eight weeks. Chasing paces derived from a result you can no longer reproduce turns every workout into a failed test.
Can I use a time trial instead of a race?
Yes, with a correction. Solo time trials typically run ten to twenty seconds per mile slower than a race of the same fitness because there is no field to pull you along and no bib to concentrate the mind. Either accept slightly conservative paces or subtract that margin knowingly.