Negative Split Calculator
Generate a negative split pacing strategy for your next race. Set your target time and how much faster you want to run the second half.
2–3% is a common target for a negative split race.
Race day gear for pacing precision
Executing a negative split on race day is much easier with a GPS watch that keeps you honest in the first half.
Garmin Forerunner 265
Real-time pace alerts prevent you starting too fast. Race predictor adjusts your target as conditions change.
View on AmazonSiS Go Energy Gels
Fuel the second half push with easy-to-digest gels. Take one every 30–45 minutes from the 45-minute mark.
View on AmazonCompression Socks
Support leg muscles during the final miles when fatigue sets in - popular choice for marathon runners.
View on Amazon
I'm Doing My Best Running Jersey
Lightweight, breathable unisex sports jersey in neon yellow. Designed for runners who keep showing up.
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Marathon training plans
Structured marathon plans from beginner finisher to sub-4 hour, with weekly mileage progression and taper guidance.
Beginners Marathon Finisher Plan
£6.99
Breaking the 4 Hour Marathon Training Plan
£6.99
Intermediate 4:30 Marathon Running Plan
£6.99
How the Negative Split Calculator works
A negative split means running the second half of a race faster than the first. The calculator distributes your target time across each kilometre, progressively increasing pace from start to finish. A 2–3% second-half advantage is a widely-used target for road races.
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Frequently asked questions
What is a negative split?
A negative split is when you run the second half of a race faster than the first. It is one of the most effective pacing strategies for distance running - research consistently shows that starting conservatively leads to faster overall times.
How much faster should my second half be?
In most road races, 1–3% faster in the second half is realistic. Going out too conservatively wastes the early miles; going too fast early burns your glycogen too quickly. A 2% negative split is a practical target for most runners.
Which races benefit most from negative splits?
Half marathons and marathons benefit most due to the glycogen demands over the final miles. In a 5K, the difference between splits is smaller, though the strategy still applies.