Pace & speed

Worked example. 10 km in 50:00 → 3000 s ÷ 6.2137 mi = 483 s/mi = 8:03 /mi; ÷ 10 km = 300 s/km = 5:00 /km; speed = 6.2137 ÷ 0.8333 h = 7.46 mph (12.0 km/h).

Race prediction (Riegel)

A 20:00 5K predicts a 10K of 1200 × (10000/5000)^1.06 ≈ 41:39. The 1.06 exponent models how pace fades as distance grows.

VO₂ max (Daniels VDOT) & training paces

VDOT is estimated from your velocity and effort duration, then each training zone targets a percentage of VO₂ max — Easy ≈ 70%, Marathon ≈ 84%, Threshold ≈ 88%, Interval ≈ 98%, Repetition ≈ 105%. The tool inverts the oxygen-cost equation to turn each target into a pace.

Calories (ACSM)

VO₂ (ml/kg/min) = 0.2 × speed(m/min) + 0.9 × speed × grade + 3.5; calories = VO₂ × weight(kg) ÷ 1000 × 5 × minutes. Elevation adds grade; heavier runners burn more.

What is running pace?

Running pace is how long it takes you to cover a set distance — usually expressed as minutes per mile or minutes per kilometer. It's the single most useful number in running because it turns an abstract effort into something you can plan around: if you know your pace, you know your finish time, your splits, and how hard a given run should feel. Everything else in this guide builds on it.

Pace vs speed vs cadence

Pace is time per distance; speed is distance per time. They're two views of the same effort — an 8:00 mile is 7.5 mph — but runners think in pace because races are measured in fixed distances. Cadence is different again: it's your step rate (steps per minute), part of how you produce a pace. Improving cadence and stride length is one route to a faster pace, but pace is the outcome you actually race on.

How to calculate pace

Divide your time by your distance. Run 5 km in 25 minutes and your pace is 5:00 per kilometer, or about 8:03 per mile. To go the other way — from a target pace to a finish time — multiply pace by distance. This calculator does both instantly and adds the conversions between miles and kilometers, so you never have to juggle the 1.609 factor yourself.

Race pacing strategies

How you distribute effort across a race matters as much as your fitness. Even pacing — holding a steady pace throughout — is simple and effective. Negative splits, running the second half faster than the first, is the strategy most associated with personal bests, because it banks energy early and finishes strong. Positive splits, slowing in the second half, usually signal starting too fast — the most common racing mistake there is. Use the split table above to set target times at each checkpoint and resist the urge to bank time early.

Marathon pacing

The marathon punishes over-eagerness more than any other distance. A pace that feels easy in the first 10K can become unsustainable by 30K as glycogen depletes and fatigue accumulates — the infamous "wall." Most experienced marathoners aim for even or slightly negative splits and hold something in reserve for the final 10K. Your predicted marathon time here assumes appropriate training and fueling; treat it as a ceiling to train toward, not a guarantee.

Training pace zones

Not every run should be run at race pace. Effective training spreads effort across zones: easy and recovery runs build aerobic base and let you absorb hard work; marathon and threshold/tempo paces raise your sustainable speed; interval work sharpens VO₂ max; and repetition paces improve speed and economy. The zones shown above are derived from your VDOT so each hits the intended intensity. The classic guidance holds: run most of your miles easy, and make the hard days genuinely hard.

VO₂ max and what it means

VO₂ max is the maximum rate at which your body can use oxygen during intense exercise — a strong predictor of endurance performance. We estimate it from a race result using Jack Daniels' VDOT model, which links your running velocity and effort duration to oxygen cost. It's an estimate from one performance rather than a lab test, but it's remarkably useful: a rising VDOT over months is clear evidence your training is working, and it anchors all your training paces.

Heart-rate training, briefly

Pace and heart rate are complementary. Pace tells you the output; heart rate reflects the internal cost, which shifts with heat, fatigue, hills and hydration. On a hot day your easy pace might spike your heart rate, and that's your cue to slow down. Many runners pace by feel and pace on easy days and use heart rate as a guardrail, then race by pace and splits.

Improving your running pace

Pace improves through consistency more than heroics: steady weekly mileage, mostly easy, with a small dose of faster work. Add tempo runs to raise your threshold, intervals to lift VO₂ max, and strides to improve economy. Strength training and adequate sleep protect against injury so you can keep training. Progress is rarely linear — expect plateaus — but a patient runner who trains consistently for months will see their pace chart shift steadily leftward.

Fueling, hydration and common mistakes

For runs under an hour, water and normal meals are usually enough; beyond that, carbohydrate intake during the run (roughly 30–60 grams per hour) and a deliberate hydration plan become important, especially in heat. The most common mistakes are starting races too fast, doing easy runs too hard and hard runs too easy, skipping recovery, and ignoring weather. This calculator's terrain, elevation and temperature options exist precisely because those factors shift your realistic pace — plan for the conditions you'll actually face.