Race Pace and Finish Time Suite

Planning mode:

The mode changes the input path while the split tables, charts, and exports stay in one suite.

Pacing profile:

Use even pace for baseline checks, then compare controlled starts, negative splits, or late fade.

Split ladder unit:

Match race markers, watch alerts, or crew notes with kilometre or mile splits.

Finish adjustment:

Positive values slow the estimate; negative values speed it up. Default 0% is neutral.

{{ finish_adjustment_percent }}%

Riegel exponent:

Lower holds speed better over longer distances; higher assumes more slowdown.

Planned stops:

Leave at 0 for continuous running, or add a pause budget for longer events.

stops sec each

Stop placement:

Pace plan brief metrics
Metric	Value	Planning note	Copy
{{ row.metric }}	{{ row.value }}	{{ row.note }}

Race split ladder
Checkpoint	Distance	Split pace	Segment time	Cumulative time	Note	Copy
{{ row.checkpoint }}	{{ row.distance }}	{{ row.pace }}	{{ row.segmentTime }}	{{ row.cumulative }}	{{ row.note }}

Adjustment scenario guide
Scenario	Finish	Average pace	Vs baseline	Planning note	Copy
{{ row.scenario }}	{{ row.finish }}	{{ row.pace }}	{{ row.delta }}	{{ row.note }}

Pace band ladder
Band	Finish	Average pace	Vs plan	Planning note	Copy
{{ row.band }}	{{ row.finish }}	{{ row.pace }}	{{ row.delta }}	{{ row.note }}

Enter a positive race distance and a valid time, pace, speed, or training profile to build the pace plan.

Embed:

Customize

Include current inputs

Size

Advanced

Width

Height

Aspect ratio

Max height

Collapsible embed

Allow fullscreen

Referrer policy

Sandbox tokens

Every race target has two clocks: the effort a runner can hold while moving and the elapsed time that appears at the finish. A 5:00 pace per kilometre, an 8:03 pace per mile, 12.0 km/h, and a 50-minute 10 km goal can all describe the same steady race, but each wording invites a different mistake when units, stops, or distance markers are misread.

Useful pacing evidence comes from several places. A target time from a plan expresses intent, a recent race result measures demonstrated fitness, and a training block hints at endurance but hides course, weather, long runs, recovery, and how hard the work felt. Choosing the evidence source matters before any split sheet is trusted.

Race pace planning evidence and common cautions
Starting evidence	What it can support	Common mistake
Known pace or finish goal	A direct split sheet for the chosen race distance.	Treating an aspirational pace as proven fitness.
Recent race result	A performance-based projection to a nearby distance.	Stretching a short race result too far without endurance evidence.
Training summary	A rough marathon check from volume, speed, and frequency.	Forgetting that averages hide long runs, workouts, terrain, and recovery.

Elapsed time also includes non-running minutes. Watches often show the pace while the runner is moving, but race results and aid-station checkpoints use the race clock. Planned stops, walking breaks, shoe changes, bathroom stops, or crew stops all make the average race pace slower even when the running effort is unchanged.

Course diagram showing start, split checkpoints, pace, and finish clock

Race-time projections lose strength as the target distance moves away from the evidence. A 10 km result can say a lot about a half marathon, while a 5 km result tells less about a marathon because endurance, fueling, muscle damage, heat, and pacing discipline matter more as the race gets longer. Course certification and official timing also matter when comparing a target to a qualifying standard, but everyday planning still needs practical allowances for terrain, crowding, GPS error, and weather.

A defensible plan is a range, not a single magic finish. Use the neutral pace to understand the basic demand, then test slower and faster scenarios, stop budgets, and pace bands until the target still makes sense under race-day conditions.

How to Use This Tool:

Start with the planning mode that matches your strongest evidence, then check the brief before using the split table, scenarios, and charts.

Set Planning mode. Choose Plan from target pace or speed for a direct goal, Predict from a recent race for a verified prior result, or Estimate marathon from training for a rough marathon check from recent weekly running.
For direct planning, set Race distance and Target input. Pace, speed, and finish time all feed the same race clock, so confirm Projected finish, Average pace, and Target distance before changing advanced settings.
For a race prediction, enter Previous race distance, Previous race time, and Target race distance. Keep Riegel exponent at 1.06 unless you are deliberately testing stronger or weaker endurance fade.
For the training estimate, enter Weekly running distance, Average training speed, and Runs per week from the same recent block. Treat Race speed vs training speed as a required sanity check.
Choose Pacing profile and Split ladder unit. Use Even pace first, then compare Controlled start, Negative split, or Stable early, late fade when you want to see how the split ladder changes.
Open Advanced only after the neutral result looks right. Finish adjustment applies a percentage allowance, Planned stops adds elapsed pause time, and Stop placement controls which checkpoint segments receive that pause time.
If the warning appears instead of results, fix the selected mode until it produces a positive finish time. Common causes are zero distance, zero pace, zero speed, a missing previous race time, or a training profile that produces a non-positive marathon estimate.
The warning clears only after the selected path has a positive distance and one valid time, pace, speed, race-result, or training estimate.
Use Pace Plan Brief for the main result, Race Split Ladder for checkpoint pacing, Adjustment Scenario Guide for sensitivity checks, Pace Band Ladder for seconds-per-unit changes, and the chart tabs for visual comparison.

A neutral first pass makes mistakes easier to see. After the units, distance, and base finish are correct, add conditions, stops, and pacing shape one change at a time.

Interpreting Results:

Projected finish is the elapsed race-clock result after the selected calculation path, finish adjustment, and planned stops. Neutral baseline is the base moving estimate before those additions. When those two values differ, the difference comes from the adjustment percentage, the stop budget, or both.

Average pace is gross pace across the full race. It includes planned stop time, so it can be slower than the moving pace you expect to see while running. Check Race Split Ladder when a checkpoint looks slow; the affected row may include a stop or a pacing-profile weight rather than a true change in effort.

Prediction caution labels and distance ratios
Prediction caution	Distance ratio	How to use the label
`Close-distance comparison`	< 1.8	The reference and target races are close enough for a more useful first estimate.
`Moderate stretch`	≥ 1.8 and < 4.0	The projection can guide pacing, but long-run evidence and race conditions matter.
`Wide-distance stretch`	≥ 4.0	The clock should be treated as a broad planning range unless other evidence supports it.

Adjustment Scenario Guide and Scenario Finish Chart show whether the result is fragile. If a small exponent change, a +5% course allowance, or one extra weekly run moves the finish by several minutes, use the range when setting race-day checkpoints.

Do not let a precise time create false confidence. Verify the Target distance, unit choice, Prediction caution, Race speed vs training speed, and stop-adjusted split rows against recent training, course profile, heat, fueling, and the longest continuous effort you can defend.

Technical Details:

All three calculation paths reduce the race to distance in metres, time in seconds, and pace per kilometre before the final outputs are formatted. That normalization is why the same plan can display kilometres, miles, pace, speed, split rows, and chart points without changing the underlying race clock.

Direct pace planning is simple distance-time arithmetic. A pace input is converted to seconds per kilometre, a speed input becomes seconds per kilometre through 3600 / speed, and a finish-time input becomes seconds per kilometre by dividing the target finish by the selected distance.

Formula Core:

The base finish is built first, then the final elapsed finish applies any percentage adjustment and planned stop time.

\begin{matrix} T_{pace} & = & D \times P \\ T_{2} & = & T_{1} \times {(\frac{D_{2}}{D_{1}})}^{p} \\ M & = & 326.3 + 2.394 K - 12.06 V - 46.1 R \\ T_{finish} & = & T_{base} \times (1 + \frac{a}{100}) + S \end{matrix}

In these equations, D is race distance in kilometres for the direct pace calculation, P is seconds per kilometre, T1 and D1 are the previous race time and distance, T2 and D2 are the predicted target race time and distance, p is the Riegel exponent, M is marathon minutes from the training path, K is weekly kilometres, V is training speed in km/h, R is rounded runs per week, a is finish adjustment percent, and S is total planned stop seconds.

Calculation paths and validation boundaries
Path	Core mechanism	Boundary to check
`Plan from target pace or speed`	Distance multiplied by pace, or finish time divided by distance.	Distance must be positive; pace, speed, or target finish must be positive.
`Predict from a recent race`	Riegel distance-power scaling from previous time to target distance.	The visible exponent range is `0.90` to `1.20`; `1.06` is the default.
`Estimate marathon from training`	Linear marathon-minute estimate from weekly kilometres, training speed, and runs per week.	The result is rejected when the model returns a non-positive marathon time.
Adjustment and stops	Percentage adjustment is applied before planned stop seconds are added.	The visible adjustment slider runs from `-15%` to `+30%`.

The training estimate deserves special caution because the local linear formula is a sensitivity model, not a full physiology model. In the displayed equation, higher training speed and more weekly runs reduce predicted marathon minutes, while weekly distance enters with a positive coefficient. That makes Race speed vs training speed and the training scenario rows more important than the single clock value.

The split ladder divides the target distance into one-kilometre or one-mile checkpoint segments. Even pace keeps segment weights close to the average. Controlled start and Negative split assign more time to early segments and less to later ones. Stable early, late fade keeps early segments slightly lighter and puts more slowdown into the final part of the race.

Scenario, pace band, and chart mechanics
Output	How it is built	Best use
`Adjustment Scenario Guide`	Creates mode-specific alternatives such as raw baseline, faster/slower effort, exponent changes, course stress, and training changes.	Testing whether the plan survives small assumption changes.
`Pace Band Ladder`	Adds and subtracts `15`, `10`, and `5` seconds per selected split unit around the current plan.	Turning a goal into practical watch or checkpoint bands.
`Pacing Timeline`	Plots current elapsed minutes and neutral baseline minutes over the selected split unit.	Seeing where pacing shape or stop placement changes the clock.
`Scenario Finish Chart`	Plots scenario finish minutes against the current plan baseline.	Comparing the finish-time spread across assumptions.

Accuracy Notes:

Race predictions are planning estimates, not guarantees. The calculation cannot see heat, wind, hills, surface, altitude, recent illness, taper quality, fueling, shoe choice, injury risk, or whether the reference race was truly all-out.

Use certified race distances and official chip or gun times when comparing against qualifying standards.
Use recent races that match your current fitness; old personal bests can make a target look safer than it is.
Use the same stop and adjustment assumptions when comparing two versions of the same plan.

Advanced Tips:

Keep Riegel exponent at 1.06 for a neutral recent-race projection, then compare nearby values only when you have a reason to model stronger or weaker distance carryover.
Apply Finish adjustment before adding Planned stops when you want course, heat, or crowding to affect running time rather than aid-station pauses.
Set Split ladder unit to the markers you will actually see on race day. A kilometre split sheet is easier to misuse on a mile-marked course.
Use Pace Band Ladder to turn a goal into watch tolerances. The +5s, +10s, and +15s rows show how small pace changes accumulate into finish-time changes.
For the training estimate, check Race speed vs training speed before accepting the clock. A high ratio means the marathon estimate is asking for much faster racing than the average training block shows.

Worked Examples:

These examples use common inputs and the visible result labels that change when a plan is direct, projected, or adjusted.

A direct 10 km target

Choose Plan from target pace or speed, set Race distance to 10 km, and enter 5:00 per kilometre. Projected finish is 50:00, Average pace is 5:00 /km | 8:03 /mile, and Neutral baseline also shows 50:00 when no adjustment or stops are applied.

A 10 km result projected to a half marathon

Enter a 50:00 previous 10 km, set Target race distance to half marathon, and leave Riegel exponent at 1.06. Projected finish is about 1:50:19, Average pace is about 5:14 /km | 8:25 /mile, and Prediction caution reads Moderate stretch because the target is more than twice the reference distance.

A training estimate that moves too much

A marathon estimate from 55 km/week, 9.0 km/h, and 3 runs per week gives about 3:31:08, with Race speed vs training speed near 1.33 x training speed. Changing only Runs per week to 4 moves the model near 2:45:02. That large swing is a warning to treat the result as a scenario check, not a firm race goal.

A stop budget creates a slower checkpoint

A 50:00 10 km plan with one 30-second planned stop changes Projected finish to 50:30. The affected Race Split Ladder row includes the pause in Segment time, so its Split pace is slower even if the moving effort stays at the original target.

FAQ:

Which planning mode should I try first?

Use Plan from target pace or speed when your goal is already chosen. Use Predict from a recent race when a verified finish time is your best evidence. Use Estimate marathon from training only as a rough check from weekly distance, training speed, and run frequency.

Why do pace and speed both appear?

Average pace and Average speed describe the same projected finish in different units. The brief shows kilometre and mile pace so a km/mi unit mistake is easier to catch.

Why does a planned stop slow one split?

The split ladder uses elapsed race time. When Stop placement puts a pause inside a checkpoint segment, that row's Segment time and Split pace include the pause.

What does the Riegel exponent change?

Riegel exponent controls how strongly time grows as target distance increases. Lower values assume better carryover to longer distances, while higher values assume more slowdown.

Why does the training estimate look aggressive?

The marathon training path uses only Weekly running distance, Average training speed, and Runs per week. If Race speed vs training speed is high or the scenario rows move by many minutes, treat the result as a caution range.

What should I fix when the warning appears?

Check the selected planning mode first. The calculator needs a positive race distance and a valid pace, speed, finish time, previous race result, or training profile that returns a positive finish.

Are the race calculations sent to a prediction service?

The pace, split, scenario, chart, and JSON calculations run in the browser from the values on the page. The race plan is not sent to a dedicated prediction service.

Glossary:

Projected finish: The elapsed race time after the selected calculation path, finish adjustment, and planned stops.
Neutral baseline: The base moving estimate before finish adjustment and planned stop time are added.
Riegel exponent: The power value that controls distance fade in the recent-race prediction path.
Gross pace: Average pace across elapsed race time, including any planned stop time.
Prediction caution: The label that compares previous and target race distances for race-prediction confidence.
Pace band: A finish estimate produced by adding or subtracting seconds per kilometre or mile from the current plan.

References:

Competition and Technical Rules - 2026 Edition, World Athletics, 1 January 2026.
Athletic Records and Human Endurance, American Scientist, May-June 1981.
Prediction of marathon performance time on the basis of training indices, Journal of Human Sport and Exercise, September 2011.
An empirical study of race times in recreational endurance runners, BMC Sports Science, Medicine and Rehabilitation, 26 August 2016.