Running Splits Calculator

Running splits are the times recorded for each segment of a race or training run, typically each mile or kilometer. Calculating target splits from a goal finish time allows runners to execute an even-pace, negative-split, or banked-time strategy.

Even-split formula: Split Time = Goal Finish Time ÷ Total Distance

Pace formula: Pace (min/mile) = Total Time (minutes) ÷ Distance (miles) Pace (min/km) = Total Time (minutes) ÷ Distance (km)

Converting pace to speed: Speed (mph) = 60 ÷ Pace (min/mile) Speed (km/h) = 60 ÷ Pace (min/km)

Negative split strategy (recommended for races): Run the first half at 2–5% slower than goal pace; run the second half at or slightly faster than goal pace.

First-half pace = Goal Pace × 1.02–1.05 Second-half pace = Goal Pace × 0.97–1.00

Common race distances and paces for popular finish times:

5K (3.107 miles):

• 20:00 finish = 6:26/mile pace
• 25:00 finish = 8:03/mile pace
• 30:00 finish = 9:39/mile pace

Half Marathon (13.109 miles):

• 1:30:00 finish = 6:52/mile pace
• 2:00:00 finish = 9:09/mile pace
• 2:30:00 finish = 11:27/mile pace

Marathon (26.219 miles):

• 3:00:00 finish = 6:52/mile pace
• 3:30:00 finish = 8:01/mile pace
• 4:00:00 finish = 9:09/mile pace
• 5:00:00 finish = 11:27/mile pace

What each variable means:

Even splits are an identical time per mile or km throughout, and it is the simplest strategy to execute.
Positive split means running the first half faster. It leads to a fading second half and it is the most common amateur mistake.
Negative split means running the second half faster. Almost every distance world record has been set this way.

Worked example: Goal: finish a half marathon in 1:45:00 (105 minutes).

Even pace = 6,300 seconds ÷ 13.1094 miles = 480.6 sec/mile = 8:01/mile

Negative split plan, splitting at the halfway point of 6.55 miles:

• First half at 2% slower: 8:10/mile, reaching halfway in 53:33
• Second half at whatever is left: 7:51/mile, covering the last 6.55 miles in 51:27
• Total: 1:45:00

The arithmetic is perfectly symmetric: 10 seconds a mile given away early, 10 seconds a mile taken back later. What is not symmetric is your body. Ten seconds a mile is easy to find in the first half when you are fresh and nearly impossible to find in the last three miles when you are not, which is the whole argument for running it this way round.