Half Marathon Pace Calculator Formula

Understand the math behind the half marathon pace calculator. Each variable explained with a worked example.

Use the Half Marathon Pace Calculator

Formulas Used

Pace (min/mile)

pace_min_part = floor(pace_per_mile)

Pace (sec remainder)

pace_sec_part = round((pace_per_mile - floor(pace_per_mile)) * 60)

Pace (min/km)

pace_per_km = round(total_minutes / 21.0975 * 100) / 100

Average Speed

speed_mph = round(13.1 / (total_minutes / 60) * 100) / 100

Variables

VariableDescriptionDefault
target_hoursTarget Hours(hr)2
target_minutesTarget Minutes(min)0
total_minutesDerived value= target_hours * 60 + target_minutescalculated
pace_per_mileDerived value= total_minutes / 13.1calculated

How It Works

How Half Marathon Pace Is Calculated

A half marathon is 13.1 miles (21.0975 km).

Formula

Pace (min/mile) = Total Time (minutes) / 13.1

Training Notes

Your half marathon pace is typically 15-30 seconds per mile slower than your 10K pace. A proper training plan should include tempo runs at or near half marathon pace.

Worked Example

You want to finish a half marathon in 2 hours.

target_hours = 2target_minutes = 0
  1. 01Total time = 2 * 60 + 0 = 120 minutes
  2. 02Pace = 120 / 13.1 = 9.16 min/mile
  3. 03That is 9 minutes and 10 seconds per mile
  4. 04Speed = 13.1 / 2 = 6.55 mph

Ready to run the numbers?

Open Half Marathon Pace Calculator