Pace Chart Calculator
Generate per-km or per-mile splits for any race distance and target time. Choose even, negative, or positive split strategies.
Input Parameters
Quick Presets
Pacing Strategy
How do you want to distribute effort across the race?
Split Unit
Input Guide
A field-by-field explanation of every input and how it affects your pace chart.
Race Distance
selectChoose a standard distance from the dropdown or select "Custom" to enter any distance. Supported distances range from 1 Mile to 100K.
Options
For custom distances, enter the value in kilometres (or miles if using imperial units).
Target Finish Time
numberYour goal finish time in hours, minutes, and seconds. The calculator generates splits that sum to exactly this time.
Use a realistic target — the calculator will warn you if the pace is faster than world records or implausibly slow.
Pacing Strategy
radioEven = same pace throughout. Negative = start slower, finish faster. Positive = start faster, fade later. Most coaches recommend even or slightly negative.
Options
For your first race at a distance, even splits are the safest choice.
Pace Variation
numberOnly appears for negative and positive strategies. Controls the difference between your fastest and slowest split. A 3% variation is a good starting point.
Higher variation means more aggressive pacing — only use 5%+ if you have experience executing split strategies.
Split Unit
radioToggle between per-kilometre and per-mile splits. This changes the segment length and all displayed distances and paces.
Options
Plan Every Split Before Race Day
The Pace Chart Calculator generates per-kilometre or per-mile splits for any race distance and target finish time. Choose an even, negative, or positive split strategy and instantly see the exact pace you need to hit at every segment — so there are no surprises on race day.
What Is a Pace Chart?
A pace chart breaks your total race time into individual split times — one for each kilometre or mile. Instead of memorising a single average pace, you get a complete plan showing exactly when to speed up, hold steady, or ease off. Professional runners and coaches use pace charts for every race, from 5Ks to ultramarathons.
Why Use a Pace Chart Calculator?
- Prevent going out too fast — the most common race-day mistake
- Execute a negative split strategy with precise per-km targets
- Know your cumulative time at every distance marker
- Plan your race for wristband-ready split times
- Compare even, negative, and positive strategies side by side
- Free, instant, and works for any distance from 1 Mile to 100K
Who Uses a Pace Chart?
Marathon runners
Plan every kilometre of a marathon with a negative split strategy — start conservatively and build to a strong finish.
Half marathon racers
Dial in your half marathon pace chart to avoid blowing up in the second half of the race.
Coaches
Generate split sheets for athletes racing different distances and give them concrete per-km targets.
5K and 10K competitors
Even in shorter races, knowing your target split at each km marker helps maintain discipline.
Ultrarunners
Break 50K, 50-mile, and 100K races into manageable per-mile segments with built-in positive split allowance.
Race-day planners
Print or screenshot your splits and tape them to your wrist or watch for quick reference during the race.
Under the Hood
The math behind the split calculations.
Linear Pace Interpolation
For negative and positive splits, pace multipliers are distributed linearly across all segments. Each segment gets a multiplier between (1 - variation) and (1 + variation). The multipliers are normalised so their weighted average equals 1.0, preserving the exact target finish time.
Segment Boundaries
The calculator divides the total distance into equal segments (1km or 1 mile). If the distance doesn't divide evenly, the last segment is shorter. All segments use the same pace model — the last segment simply covers less distance.
Time Preservation
After applying pace multipliers, a normalisation step ensures the sum of all split times equals the target finish time to within 0.01 seconds. Any floating-point drift is absorbed by the final segment.
Privacy
All calculations run entirely in your browser using pure TypeScript math functions. Nothing is sent to any server or logged in any analytics system.
Example Scenarios
Real inputs and expected outputs from the calculator.
Sub-4 Marathon, Even Splits
A 3:59:59 marathon with even splits produces 42 segments of ~5:41/km each, plus a short final 195m segment. Every split time is identical except the last.
42.195 km · 3:59:59 · Even · 42 + 1 splits at ~5:41/km
Sub-2 Half Marathon, Negative 3%
A 1:59:59 half marathon with 3% negative splits starts at ~5:45/km and finishes at ~5:34/km. The second half is faster, targeting a strong finish.
21.1 km · 1:59:59 · Negative 3% · 21 + 1 splits
50K Ultra, Positive 5%
A 5:00:00 50K with 5% positive splits starts at ~5:50/km and fades to ~6:10/km. Realistic for ultra pacing where some slowdown is expected.
50 km · 5:00:00 · Positive 5% · 50 splits
Research & References
Pacing strategies and split calculations in this tool draw on established race-performance research.
- Daniels, J. (2013). Daniels' Running Formula (3rd ed.). Human Kinetics.
- Riegel, P. S. (1981). Athletic Records and Human Endurance. American Scientist, 69(3), 285–290.
- Abbiss, C. R., & Laursen, P. B. (2008). Describing and Understanding Pacing Strategies During Athletic Competition. Sports Medicine, 38(3), 239–252.
Frequently Asked Questions
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Heat Adjusted Pace Calculator
Enter your base pace and race-day conditions to see how heat, humidity, and altitude affect your target splits.