MathIsimple
Pace Calculator

Pace Calculator

Convert race distance and finish time into pace per mile and per kilometer — with speed, and Riegel-formula predictions for your other race distances.

Pace per Mile & per KMRiegel Race Predictions5K to Marathon Presets
Distance and Time
Pick a race distance (or custom miles) and your finish or goal time
Distance
Time (h : m : s)

Pace Chart: Finish Times at Every Pace

Pace × distance = finish time. This grid answers the race-morning question directly — find your goal time, read off the pace to hold:

Pace5K10KHalfMarathon
7:00 /mi21:4543:301:31:463:03:33
8:00 /mi24:5149:431:44:533:29:45
9:00 /mi27:5855:551:58:003:55:58
10:00 /mi31:041:02:082:11:064:22:11
11:00 /mi34:111:08:212:24:134:48:24
12:00 /mi37:171:14:342:37:195:14:37

Why Race Pace Isn't Linear: The 1.06 Exponent

Doubling the distance costs more than double the time. Riegel's exponent 1.06 means each doubling slows pace by ~4%: a runner holding 8:00/mi for a 5K holds roughly 8:20/mi for a 10K and 9:00/mi for a marathon. Worked example: 25:00 5K → 10K prediction = 25:00 × (10/5)^1.06 = 25:00 × 2.085 = 52:07. The formula's blind spot is specificity — it projects fitness, not preparation, so the marathon number assumes you've done the long-run volume the shorter race never required.

Using Pace Zones in Training

A single race pace generates a full training menu: easy runs at race pace + 60-90 s/mi (the bulk of weekly volume), tempo runs at roughly 10K-to-half pace held 20-40 minutes, and intervals at 5K pace or faster. A 28:30 5K runner (9:10/mi) thus trains easy at ~10:15-10:45, tempo at ~9:25, intervals at ~9:00 or quicker. Pair pacing with fueling via the TDEE calculator and daily mileage tracking with the steps to miles calculator.

Frequently Asked Questions

How do I calculate my running pace?
Divide total time by distance. A 28:30 5K: 1,710 seconds ÷ 3.107 miles = 550 s/mile ≈ 9:10 per mile (5:42 per km). Going the other way, planned pace × distance = target finish time — that's how goal paces for race bibs are set.
What is a good running pace for beginners?
Most new runners settle between 10:00 and 13:00 per mile for easy continuous running; a 30-35 minute 5K sits in that band. More useful than comparing to averages: easy runs should allow full sentences aloud — that conversational check tracks the aerobic zone better than any single pace number.
How does the Riegel race predictor work?
t₂ = t₁ × (d₂/d₁)^1.06 — the 1.06 exponent captures how pace degrades with distance across well-trained runners. A 25:00 5K predicts a 51:53 10K and a 4:04 marathon. The marathon prediction assumes marathon-specific training; without long runs, real times typically come in 10-20 minutes slower.
How do I convert pace per km to pace per mile?
Multiply by 1.609: a 5:00/km runner covers a mile in 5:00 × 1.609 ≈ 8:03. Handy anchors: 5:00/km = 8:03/mi, 6:00/km = 9:39/mi, 4:00/km = 6:26/mi. The calculator shows both simultaneously so treadmill (mph) and GPS-watch (min/km) users speak the same language.
What pace do I need to break 2 hours in the half marathon?
13.11 miles in 120 minutes = 9:09 per mile (5:41/km), or 6.55 mph on a treadmill. Common bib targets: sub-25 5K = 8:03/mi; sub-50 10K = 8:03/mi; sub-4 marathon = 9:09/mi — note the sub-2 half and sub-4 marathon demand the same pace, held twice as long.
Does the calculator work for walking and cycling?
Yes — pace is just time over distance. A 15:00/mile walking pace is 4 mph; cyclists usually think in speed rather than pace, which the mph line provides. For the calorie side of walking, our calories-burned-walking calculator uses the same speed input.
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Disclaimer: This calculator is for general educational purposes only and is not medical advice. It does not diagnose, treat, or replace consultation with a qualified healthcare professional. Always discuss your results with your doctor.