What is a negative split?

The second half is completed faster than the first. This tool uses a 1 to 5% reduction in second-half time.

How much faster should the second half be?

Choose 1 to 5% for this model. Suitability depends on the course and your pacing experience.

Do hills change my splits?

The model does not include gradients, weather or terrain. Adjust expectations for the course.

Should I bank time early?

This tool models even or negative pacing; it does not prescribe faster early splits.

An unbranded stopwatch beside white track lane markings

Make your next run count

Race split planner

See the split and elapsed times needed to reach your finish-time goal.

Enter your race distance and goal time, then choose an even pace or a faster second half. The table shows each kilometre or mile split and your total elapsed time at every marker, including the finish. Keep a copy as a PDF or download the splits for a spreadsheet.

Split time is the time for one section; elapsed time is the total since the start. The final row includes any remaining part of a kilometre or mile and finishes exactly on your goal.

ByStrideSheet team

Free to useOn your deviceReady to print

Your race splits

Your split and elapsed times.

Goal finish time

Negative split 2%

50:00

6.2137 miles race

Average pace

8:03 /mile

First half: 8:08 /mile; Half time 25:15
Second half: 7:58 /mile; Half time 24:45

Split targets

7 markers

Distance in miles, split time, and elapsed time at every marker, including the finish.
Distance (miles)	Split time	Elapsed
1	8:08	8:08
2	8:08	16:15
3	8:08	24:23
4	7:59	32:22
5	7:58	40:20
6	7:58	48:18
Finish6.2137 miles	1:42	50:00

For general information only, not professional advice. Check the official sources below. Use your own judgement and speak to a qualified professional before you act.

A little context

Get more from your result.

The steps, examples and sources
behind this tool.

Set your race split targets

Choose a standard race distance or enter a custom distance.
Enter goal time and select kilometres or miles.
Choose even pacing or a negative split from 1 to 5%.
Read the markers, download the table with Save PDF, share settings, print or download CSV.

A worked example

10 km, 50:00 goal, negative 2%.
First 5 km: 5:03/km; last 5 km: 4:57/km.
Final elapsed time: 50:00.

How this tool works

For a negative split s expressed as a decimal, first-half time equals goal time divided by (2 - s). Second-half time equals first-half time multiplied by (1 - s).

Each half's pace is its time divided by half the distance. A split crossing halfway includes both paces. Even pacing uses s = 0.

Markers occur at whole kilometres or miles, followed by the exact finish distance. The last elapsed time equals your goal exactly. Calculations keep precision; only displayed times round to the nearest second.

A few useful answers

Sources

World Athletics: Competition and Technical Rules (2026 edition), Technical Rule 55.1
Technical Rule 55.1, PDF page 250: Road Mile 1609.344 m and Marathon 42.195 km. Half-marathon distance is confirmed by the separate discipline record.
World Athletics: Marathon (discipline page)
Marathon distance: 26 miles 385 yards (42.195 km).
World Athletics: Half marathon (discipline page)
Half marathon distance: 21.0975 km, exactly half a marathon.
National Institute of Standards and Technology (NIST): NIST Guide to the SI, Appendix B.8: Factors for Units Listed Alphabetically
One mile = 1609.344 metres (exact factor).

Last checked: 13 October 2026

StrideSheet team

We build free running tools: training plans built to your race date, pace bands and race-day plans. Our plans follow published training principles and are a guide, not medical advice.