Running pace, speed, time — how the calculator works

The goal of a running pace calculator is simple: it keeps distance, time, pace, and speed consistent. If you know any two of them (in the right combination), the others can be computed using straightforward formulas.

• Distance is how far you run (e.g., 5 km, 3.1 miles, 400 m).
• Time is how long it takes (e.g., 00:25:30).
• Pace is time per unit distance (e.g., 5:06 min/km or 8:13 min/mile).
• Speed is distance per unit time (e.g., 11.8 km/h or 7.3 mph).

• Pace = Time ÷ Distance
  If time is in seconds and distance is in kilometers, pace becomes seconds per kilometer (then we format as min:sec).
• Time = Pace × Distance
  If pace is 300 sec/km (5:00) and distance is 10 km, time is 3000 seconds (50:00).
• Speed = Distance ÷ Time
  Then converted to km/h or mph. For km/h: speed(km/h) = distance(km) ÷ time(hours).
• Speed ↔ Pace conversion
  In km: pace(sec/km) = 3600 ÷ speed(km/h). In miles: pace(sec/mi) = 3600 ÷ speed(mph).

You might enter distance in miles but want pace in min/km, or enter pace in min/mile but want speed in km/h. This page handles all conversions behind the scenes:

• 1 mile = 1.609344 km (used for mile ↔ km pace and speed translations).
• 1 km = 1000 m (used for track-style distances like 400 m).
• 1 hour = 3600 seconds (used for speed ↔ pace conversions).

Splits answer the practical question: “If I keep this pace, what time will I hit at each kilometer (or mile)?” The calculator builds a split table by multiplying your per-km (or per-mile) pace by 1, 2, 3… until the distance is reached. This is perfect for:

• Race planning (avoid starting too fast).
• Tempo runs (hold a target pace consistently).
• Sharing progress (screenshots of clean split tables are very “runner social”).

• Example A: 5K in 25:00
  Distance = 5 km, Time = 25:00 → Pace = 25:00 ÷ 5 = 5:00 min/km. Convert to min/mile: 5:00 min/km ≈ 8:03 min/mile. Speed: 5 km in 0.4167 h → 12.0 km/h.
• Example B: Pace 9:00 min/mile for 10K
  10K is 6.2137 miles. Time = 9:00 × 6.2137 = 55.923 minutes → about 55:55. Speed: 60 ÷ 9 = 6.67 mph (≈ 10.73 km/h).
• Example C: Treadmill at 10 km/h for 30 minutes
  Distance = speed × time = 10 km/h × 0.5 h = 5 km. Pace = 60 ÷ 10 = 6:00 min/km (≈ 9:39 min/mile).

The most shareable outputs are: (1) your pace in both units (min/km and min/mile), (2) your predicted finish time for a common distance (5K/10K/half/marathon), and (3) the split table screenshot. That’s why this calculator includes presets and a copy/share button set.

Frequently Asked Questions

• What’s the difference between pace and speed?

  Pace is time per distance (e.g., 5:30 per km). Speed is distance per time (e.g., 11 km/h). Runners often talk pace; machines often show speed. This tool converts both ways.

• Which pace unit is more common: min/km or min/mile?

  Many countries use min/km, while the U.S. often uses min/mile. Both are valid — choose the one your community uses, or display both when sharing.

• Why do my real splits differ from this split table?

  Real running is rarely perfectly even: hills, turns, wind, water breaks, crowds, and fatigue change pace. The split table assumes steady pace for planning and reference.

• Can I use this for walking or cycling?

  Yes. The math is the same for any movement. Just enter the right distance and time.

• What’s a “good” pace?

  “Good” depends on your goals, experience, and health. Compare your pace to your own history, not someone else’s highlight reel.

• Does this calculator store my data?

  No. Everything is calculated locally in your browser. Sharing only happens when you click a share button.