A training pace calculator answers a different question from a race pace calculator, and the distinction is the entire point of this page. You give it a race you have already run, and it returns the paces you should be running in training — the speed for an easy day, the speed for a tempo, the speed for intervals — each of which is slower or faster than race pace by a specific, physiologically defined amount.
Arb Digital publishes a free tools library, and this page deliberately does not overlap with four tools already in it. The running pace calculator solves the pace, time and distance triangle: you give it two of the three and it returns the third, which is what you want when planning how fast to run a race. This page never answers that question. It takes a finished result as its input and returns five prescribed workout paces as its output. Different input, different output, different job.
The other three: the marathon time predictor forecasts a finishing time for one specific distance from a shorter result, which is a prediction rather than a prescription. The pace converter converts a single pace between minutes per mile, minutes per kilometre and speed units. The treadmill pace calculator translates a treadmill's belt speed and incline into an outdoor-equivalent effort. None of them prescribes training zones, and this page does nothing else.
What This Training Pace Calculator Does
It converts one race result into a VDOT value — a single number representing current running fitness — and then derives five training paces as fixed intensity fractions of it.
Easy is the pace for the large majority of weekly volume, including long runs and recovery days. Marathon pace is the steady, controlled effort used in longer specific work. Threshold is the pace you could hold for roughly an hour in a race, used for tempo runs and cruise intervals, and it is the workhorse of most training plans. Interval pace is close to the speed that stresses maximal aerobic capacity, used for repeats of three to five minutes. Repetition pace is faster still and short, used for running economy and mechanics rather than aerobic development.
Alongside each pace it shows a heart-rate band as a percentage of the maximum you enter. Those bands are an approximation offered for convenience, not an independent measurement — heart rate lags effort, drifts with heat and dehydration, and varies day to day, which is exactly why pace-based prescription exists.
How to Use It
- Use a recent result, run hard. A race from the last six weeks, run to something close to your limit, is the only valid input. A time-trial in training works if you genuinely emptied the tank.
- Prefer a distance between 5 km and a half marathon. Very short races overstate aerobic fitness and very long ones understate it, because both sit at the edges of the model's fit.
- Enter the time exactly. Both mm:ss and hh:mm:ss are accepted, so 45:00 and 1:38:20 are both fine.
- Pick your easy intensity honestly. The default of 70% is the standard. If you are returning from a break or running the day after a hard session, drop it.
- Recalculate every four to six weeks. VDOT moves as fitness moves, and running to a stale set of paces is the most common way a plan goes wrong.
The Formula / How It's Calculated
The calculation runs in three steps, all of them from Jack Daniels' published VDOT model.
Step one — oxygen cost of your race velocity. With velocity v in metres per minute, VO₂ = −4.60 + 0.182258 × v + 0.000104 × v². This gives the oxygen demand of running at that speed.
Step two — what fraction of maximum that represents. A race lasting t minutes is run at a predictable percentage of maximal aerobic capacity: fraction = 0.8 + 0.1894393 × e−0.012778t + 0.2989558 × e−0.1932605t. Short races use a higher fraction, long ones a lower one. VDOT = VO₂ ÷ fraction.
Step three — invert for each training zone. Each zone is a fraction of VDOT: easy at 65–74%, marathon at 84%, threshold at 88%, interval at 98% and repetition at 105%. Multiplying VDOT by the fraction gives a target oxygen cost, and solving the step-one quadratic backwards gives the velocity that produces it: v = (−0.182258 + √(0.182258² + 0.000416 × (VO₂ + 4.60))) ÷ 0.000208. Pace is then 1,000 ÷ v minutes per kilometre.
Worked example, matching the values this page loads with. A 10 km in 45:00. Velocity is 10,000 ÷ 45 = 222.22 m/min, so VO₂ = −4.60 + 40.502 + 5.136 = 41.04. For t = 45 minutes the fraction is 0.8 + 0.1066 + 0.00005 = 0.9066, giving a VDOT of 45.3. Running the inversion at each intensity produces an easy pace of 5:32 per km, marathon pace 4:47, threshold 4:37, interval 4:14 and repetition 4:00. Note where race pace sits: the 10 km was run at 4:30 per km, comfortably between threshold and interval, which is exactly where a 45-minute effort belongs.
Why Easy Pace Is Slower Than You Think
The single most common reaction to a set of VDOT paces is that easy pace looks absurdly slow. In the worked example it is more than a minute per kilometre slower than the race that generated it. That gap is not an error, and closing it is the most reliable way to stall a training block.
Easy running exists to accumulate volume at an intensity that produces aerobic adaptation without meaningful recovery cost. Run it faster and you get slightly more stimulus at disproportionately more fatigue, which then degrades the quality of the sessions that actually drive improvement. The result is the familiar plateau: every run moderately hard, no run genuinely hard, no progress.
This is not a fringe position. A review of the training intensity distribution among well-trained and elite endurance athletes examined how elite endurance athletes actually distribute their training and found that the large majority of volume sits at low intensity, with pyramidal and polarised distributions dominating and experimental comparisons favouring polarised approaches over threshold-heavy ones. The same review is careful to note that no single optimal distribution can be identified across sports and individuals — but the direction is consistent, and it is not towards running everything at a moderate effort.
It is worth separating this from general health guidance, which answers a different question. The American College of Sports Medicine's Physical Activity Guidelines resources describe how much aerobic and muscle-strengthening activity adults should accumulate for health. That is a floor for the general population, not a distribution for a runner chasing a personal best — the zones on this page are about how to allocate training you are already doing.
A practical test: if you cannot hold a conversation in full sentences, you are not running easy, whatever the watch says.
Threshold Is the Session That Moves the Needle
If you can only add one hard session a week, the evidence and the practice both point at threshold work.
Threshold pace is roughly the fastest you could sustain for about an hour under race conditions, which for most runners falls between 10 km and half marathon pace. Physiologically it sits at the point where lactate production and clearance are balanced, and training there raises the speed at which that balance breaks. Because the effort is hard but not maximal, you can accumulate 20 to 40 minutes of it in a session — far more stimulus than an interval workout delivers, at a fraction of the recovery cost.
Two formats dominate. A continuous tempo of 20 to 40 minutes at threshold pace is the simplest. Cruise intervals break the same volume into repeats of five to fifteen minutes with short recoveries, which lets less experienced runners hold the pace properly rather than drifting. Both work; the second is more forgiving of pacing errors.
The most common mistake is running threshold too fast. It is not a race effort, and the difference between threshold and interval pace in the worked example above is only 23 seconds per kilometre — small enough to cross by accident, large enough to turn a repeatable session into one that costs three days.
What VDOT Cannot Tell You
The model is a fit to observed race performances, and it inherits the limits of that fit.
It assumes you are trained for the distance you raced. A runner with a fast 5 km and no long-run history will get a VDOT that overstates their marathon readiness, because the model converts across distances on the assumption of appropriate preparation.
It says nothing about durability. Two runners with identical VDOT values can have completely different capacities to absorb weekly volume, and the paces do not know which one you are.
Terrain, heat and altitude are absent. The prescribed paces assume flat ground in reasonable conditions. On a hot day or a hilly route, run to effort and let the pace fall where it falls — this is where a heart-rate check earns its place, and the heart rate zone calculator covers those bands in more detail.
Aerobic capacity is only one input to performance. Running economy, fatigue resistance and pacing all contribute, which is why two runners with the same VDOT can race quite differently. The VO2 max calculator estimates the underlying capacity from field tests if you want the physiological figure rather than the training prescription.
Arb Digital builds fast, dependency-free calculators and interactive tools that load instantly, rank in search and keep visitors reading.
Browse the Free Tools Talk to Arb DigitalCommon Mistakes to Avoid
- Using an old personal best — the paces describe current fitness, and a result from two years ago prescribes work you cannot currently absorb.
- Running easy days at marathon pace — the gap between those two zones exists to protect the hard sessions, and closing it degrades everything downstream.
- Treating threshold as a race effort — it is the pace you could hold for about an hour, not the pace you would race for twenty minutes.
- Holding the prescribed pace on a hot or hilly day — the model assumes flat ground and reasonable conditions, and forcing the number turns an easy run into a hard one.
- Never recalculating — VDOT moves with fitness, and paces set at the start of a block are wrong by the end of it.
Related Free Tools From Arb Digital
Use the running pace calculator when you want to solve pace, time and distance for a race rather than prescribe training zones, the marathon time predictor to forecast a marathon finish from a shorter result, the pace converter to switch a single pace between units, and the treadmill pace calculator to translate belt speed and incline into outdoor effort. The heart rate zone calculator and VO2 max calculator cover the physiological side. Everything else is in the free online tools hub.
Frequently Asked Questions
The running pace calculator solves the pace, time and distance triangle — give it two and it returns the third, which is what you need to plan how fast to run a race. This page never answers that. It takes a race you have already finished as its input and returns five prescribed workout paces for training. Different inputs, different outputs, different purpose.
A single number representing current running fitness, derived from a race result by working out the oxygen cost of the velocity you held and dividing by the fraction of maximum that a race of that duration is run at. It is used as an index for prescribing training paces rather than as a laboratory measurement.
The most recent one you ran hard, ideally within the last six weeks and between 5 km and a half marathon. Very short races overstate aerobic fitness and very long ones understate it, because both sit at the edges of the model's fit.
Because easy running exists to accumulate aerobic volume without meaningful recovery cost. Running it faster adds a little stimulus and a lot of fatigue, which degrades the quality of the sessions that actually drive improvement. If you cannot speak in full sentences, it is not easy.
Tempo runs and cruise intervals. It is roughly the fastest pace you could hold for an hour, sitting where lactate production and clearance balance, and training there raises the speed at which that balance breaks. Twenty to forty minutes at threshold is the highest-value single session in most weeks.
Every four to six weeks, or after any race that meaningfully beats your previous result. Fitness moves, and running a whole block to paces set at the start of it means training too easily by the end.
Follow the pace on flat ground in reasonable conditions, and follow effort when it is hot, hilly or humid. Heart rate lags effort and drifts with heat and dehydration, so the bands shown here are a cross-check rather than a second measurement.
This tool applies a published training model to a race result you supply. It is general fitness information, not medical advice or a coaching prescription for you specifically, and anyone starting or intensifying training — particularly after illness, injury or a long break — should speak to a qualified professional first.
