This professional-grade pace calculator helps runners, coaches, and fitness enthusiasts compute running pace, speed, time, or distance with precision. It supports both metric and imperial units, provides automatic conversions, and offers projected finish times for popular race distances.

Data Source and Methodology

Authoritative Data Source: NIST Special Publication 811 (2019 Edition): Guide for the Use of the International System of Units (SI). National Institute of Standards and Technology. Direct link. Definitions used include the exact relationships: 1 hour = 3600 seconds; 1 mile = 1.609344 kilometers.

Tutti i calcoli si basano rigorosamente sulle formule e sui dati forniti da questa fonte.

The Formula Explained

Core relationships (LaTeX):

1) Speed: v = d / t ⇒ v_{km/h} = \dfrac{d_{km}}{t_{h}}

2) Pace: p = t / d ⇒ p_{min/km} = \dfrac{t_{min}}{d_{km}}, \quad p_{min/mi} = \dfrac{t_{min}}{d_{mi}}

3) Solve for time: t = p \times d

4) Solve for distance: d = t / p

5) Unit conversion: 1\,\text{mi} = 1.609344\,\text{km}; \quad 1\,\text{h} = 3600\,\text{s}

Glossary of Variables

Distance (d): Length of the run, in kilometers or miles.
Time (t): Total elapsed time (hh:mm:ss).
Pace (p): Time per unit distance (min/km or min/mi).
Speed (v): Distance per unit time (km/h or mph).
Preset Distance: Quick selector for common events (5K, 10K, Half, Marathon).
Splits: Cumulative times at regular unit intervals (km or mile).

How It Works: A Step-by-Step Example

Scenario: You ran 5 kilometers in 25 minutes and want to know your pace and projected 10K time.

  1. Enter distance d = 5 km.
  2. Enter time t = 00:25:00.
  3. Compute pace p using p = t / d = 25 min / 5 km = 5.00 min/km.
  4. Convert to min/mile: p_{min/mi} = 5.00 × 1.609344 ≈ 8.03 min/mi (≈ 8:02).
  5. Speed v = distance/time = 5 km / (25/60 h) = 12 km/h; mph ≈ 7.46.
  6. Projected 10K time: t = p × d = 5.00 min/km × 10 km = 50 minutes.

Frequently Asked Questions (FAQ)

How do I switch between km and miles?

Use the unit dropdown next to Distance. All conversions and results update automatically.

Can I calculate time or distance instead of pace?

Yes. Use “Solve for” to choose Pace, Time, or Distance. The calculator enables the relevant inputs.

What is the difference between pace and speed?

Pace is time per unit distance (e.g., min/km) while speed is distance per unit time (e.g., km/h). They are reciprocals.

Are the race projections exact?

No. They assume a constant pace and don’t factor terrain, fatigue, or conditions. Use them as estimates.

Do you use accurate unit conversions?

Yes. Conversions follow NIST definitions: 1 mile = 1.609344 km; 1 hour = 3600 s.

Why doesn’t the calculator accept 62 minutes?

Minutes and seconds fields use 0–59. If your time is 62 minutes, enter 1 hour and 2 minutes instead.

How many splits are shown?

Up to the first 10 unit splits for readability, plus the final finish time.

Tool developed by Ugo Candido. Content verified by the CalcDomain Expert Team.
Last reviewed for accuracy on: .