Pace Calculator

Pace measures how long it takes to cover a fixed distance (minutes per kilometre or per mile). Speed measures how much distance is covered per unit of time (km/h or mph). Runners use pace because smaller pace numbers feel more sensitive; cyclists prefer speed. Both describe the same effort — simply inverted: speed = 60 ÷ pace(min/km) km/h.

The Peter Riegel formula T₂ = T₁ × (D₂ ÷ D₁)^1.06 is widely used and typically within 2–4% of actual finish times for trained runners covering distances from 5K up to the marathon. Accuracy drops for untrained runners, hilly courses, extreme weather, and when extrapolating far from the input distance (e.g. 1 mile → marathon). Treat predictions as a guideline, not a guarantee.

A negative split means running the second half of a race faster than the first. It is associated with better pacing discipline and often yields personal bests. To execute it, hold back slightly in the early miles (5–10 seconds per km slower than goal pace), then accelerate gradually. Starting too fast depletes glycogen and causes the dreaded positive split where you slow down in the final kilometres.

Roughly: easy runs at 60–90 seconds per km slower than 10K race pace; tempo/threshold around 15–25 seconds slower than 10K pace; interval/VO₂ max at mile race pace or slightly faster; recovery at whatever feels effortless. Polarised training spends ~80% of weekly mileage in the easy zone and ~20% at threshold or harder.

Treadmills reduce wind resistance and propel the belt under you, so the effort is typically 2–5% lower than outdoor running at the same displayed speed. Setting the incline to 1% compensates for most of the difference. Also check treadmill calibration — many consumer machines drift by 5–10% over time.

Every 1% of uphill grade slows pace by roughly 12–15 seconds per mile (8–10 s/km) at moderate effort. Downhills recover about half that amount because braking muscles and footstrike impact limit gain. For hilly routes, judge effort by heart rate or perceived exertion rather than pace, and save pace analysis for flat segments.

Pace measures how long it takes to cover a fixed distance (minutes per kilometre or per mile). Speed measures how much distance is covered per unit of time (km/h or mph). Runners use pace because smaller pace numbers feel more sensitive; cyclists prefer speed. Both describe the same effort — simply inverted: speed = 60 ÷ pace(min/km) km/h.

The Peter Riegel formula T₂ = T₁ × (D₂ ÷ D₁)^1.06 is widely used and typically within 2–4% of actual finish times for trained runners covering distances from 5K up to the marathon. Accuracy drops for untrained runners, hilly courses, extreme weather, and when extrapolating far from the input distance (e.g. 1 mile → marathon). Treat predictions as a guideline, not a guarantee.

A negative split means running the second half of a race faster than the first. It is associated with better pacing discipline and often yields personal bests. To execute it, hold back slightly in the early miles (5–10 seconds per km slower than goal pace), then accelerate gradually. Starting too fast depletes glycogen and causes the dreaded positive split where you slow down in the final kilometres.

Roughly: easy runs at 60–90 seconds per km slower than 10K race pace; tempo/threshold around 15–25 seconds slower than 10K pace; interval/VO₂ max at mile race pace or slightly faster; recovery at whatever feels effortless. Polarised training spends ~80% of weekly mileage in the easy zone and ~20% at threshold or harder.

Treadmills reduce wind resistance and propel the belt under you, so the effort is typically 2–5% lower than outdoor running at the same displayed speed. Setting the incline to 1% compensates for most of the difference. Also check treadmill calibration — many consumer machines drift by 5–10% over time.

Every 1% of uphill grade slows pace by roughly 12–15 seconds per mile (8–10 s/km) at moderate effort. Downhills recover about half that amount because braking muscles and footstrike impact limit gain. For hilly routes, judge effort by heart rate or perceived exertion rather than pace, and save pace analysis for flat segments.