Pace Band Generator

Target{{ resultsReady ? formatDuration(computation.values.target_seconds) : '—' }} Distance{{ resultsReady ? formatDistance(computation.values.distance_km, computation.normalizedInputs.distance_unit, 2) : '—' }} Markers{{ resultsReady ? computation.values.marker_count : '—' }}

Race distance preset:

Presets update distance, marker spacing, and a representative target time.

Exact race distance:

Accepted range: 0.05 to 200 km-equivalent.

Target hours and minutes:

min

Hours first, minutes second. Add seconds below when the goal is more precise.

Target seconds:

sec

The total target must be at least one minute.

Marker spacing:

Use official markers where possible; the final row covers any shorter remainder.

Pacing shape:

Shape strength:

Adjust shape

Zero makes every strategy even; 1–2% is subtle and 5% or more is intentionally pronounced.

Band density:

The full checkpoint ledger always remains available.

Display rounding:

Rounding is presentation-only and never feeds later calculations.

Course allowance:

Adjust allowance

The neutral default is 0%; values above 1.5% produce a caution.

Stop buffer per marker:

sec

Adjust stop buffer

The neutral default is 0 seconds; buffers reduce the moving-time budget.

Pace display basis:

Use the unit that matches the course signs or your watch.

{{ raceBandText }}

The chart renderer is unavailable. The checkpoint ledger still contains every planned pace.

Marker	Segment	Cumulative	Pace	Vs even	Cue	Copy
{{ row.marker }}	{{ row.segment }}	{{ row.cumulative }}	{{ row.pace }}	{{ row.delta }}	{{ row.cue }}

Strategy	First marker	Halfway	Final marker	First half	Second half	Copy
{{ row.label }}	{{ row.firstMarker }}	{{ row.halfway }}	{{ row.finalMarker }}	{{ row.firstHalf }}	{{ row.secondHalf }}

A finish-time goal is useful during a race only when it becomes a clock reading at a marker. A pace band turns the goal into cumulative checkpoints so a runner can look down at 5 km, 10 km, halfway, or another marked distance and see whether the race is close to plan.

Average pace alone assumes every kilometre or mile should take the same time. That may be the right plan, but runners also use a controlled opening, a faster second half, an intentionally faster first half, or a late-fade allowance. Each shape redistributes moving time across the course while preserving the same finish target.

Pacing shapes and their intended use
Shape	Clock pattern	Main caution
Even pace	Equal moving pace from start to finish.	Hills, wind, crowding, and aid stations can make equal effort look uneven on the clock.
Controlled start	Patient opening, settling middle, slightly faster close.	An exaggerated opening adjustment can leave too much work late.
Negative split	First half slower than the second half.	The faster finish must be realistic for the runner and course.
Positive split	Faster early running followed by a slower finish.	Banked time can become accumulated fatigue rather than protection.
Late-fade guardrail	Steady early pace with extra time reserved for the closing section.	It describes a contingency, not a prediction of fatigue.

Course distance and travelled distance are not always identical. Turns, crowd movement, water stops, and a line that is wider than the measured shortest route can add distance. A course allowance models that extra effort, while a stop buffer reserves clock time at every marker except the finish. Both settings reduce the moving-time budget, so they make the required running pace faster.

Marker spacing should match signs or landmarks that will actually be available. When the distance is not an exact multiple of the spacing, the last segment is shorter and the finish still lands on the target time. A band with every marker is useful for close monitoring; a sparse band is easier to read while moving.

Race pacing is a plan, not a forecast. Weather, elevation, surface, congestion, fueling, health, and GPS error can all make a mathematically reconciled band inappropriate on the day. Check effort and conditions rather than forcing a checkpoint at the expense of safety.

How to Use This Tool:

Build the clock plan from official distance and markers before adding strategy adjustments.

Choose a race preset or enter the exact Race distance and unit. Enter a target time of at least one minute.
Set Marker spacing to a distance no greater than the race. Use the unit printed on course signs when possible; the final row covers any shorter remainder.
Select a Pacing shape and keep Shape strength modest unless a pronounced change is intentional. A strength of 0% makes every shape equivalent to even pace.
Add Course allowance or a Stop buffer per marker only when the finish target includes them. Review the resulting moving pace because both adjustments consume time or distance.
Choose band density, pace display unit, and display rounding. Check the final cumulative row and the Strategy check before relying on the band.

Interpreting Results:

Read cumulative time at the course marker, not the segment duration beside it. The finish row should equal the target time before display rounding. The Pace profile compares planned segment pace with the even-pace reference, while the Strategy check exposes first-marker, halfway, and closing behavior across all five shapes.

Moving pace excludes reserved stops and reflects any course allowance. Elapsed pace divides the full target time by the official course distance.
A value above even pace in seconds per kilometre means a slower segment; a value below even pace means a faster segment.
Rounded rows are reading aids. Rounding to 5 or 10 seconds can make displayed splits differ slightly from one another, but it never changes the underlying finish reconciliation.
Course allowance above 1.5% triggers a caution because the extra distance materially changes the required moving pace.

Technical Details:

The model converts distance and marker spacing to kilometres, reserves stop time, scales each official segment by the course allowance, and assigns a strategy weight at the segment midpoint. A normalization step then makes the sum of all weighted segment times land exactly on the target.

Formula Core:

With official distance D, marker spacing m, target time T, stop buffer b, and course allowance a as a decimal, the marker and running budgets are:

\begin{matrix} n & = & ⌈ \frac{D}{m} ⌉ \\ T_{stop} & = & \max (0, n - 1) \times b \\ T_{run} & = & T - T_{stop} \\ D_{effort} & = & D (1 + a) \end{matrix}

For segment j, effort distance d_j is multiplied by the strategy weight w_j. The base pace constant q normalizes all segments to the running budget.

\begin{matrix} q & = & \frac{T_{run}}{\sum_{j = 1}^{n} d_{j} w_{j}} \\ t_{j} & = & d_{j} q w_{j} \end{matrix}

Each cumulative checkpoint adds the stop buffer before a non-start segment and then adds that segment's moving time. The final checkpoint therefore equals T to full calculation precision.

Strategy Rule Core:

Progress p runs from 0 at the start to 1 at the finish. Strength is capped at 8% and converted to amplitude A. The weights shape relative pace; normalization preserves total time.

Pace strategy weight rules
Strategy	Weight rule	Effect
Even	`w` = 1	No pace redistribution.
Negative split	`w` = 1 + `A`/2 − `pA`	Weights decrease steadily, so later pace is faster.
Positive split	`w` = 1 − `A`/2 + `pA`	Weights increase steadily, so later pace is slower.
Controlled start	Full opening adjustment through 15%, taper toward even through 72%, then a modest faster close.	Three-piece transition rather than a straight line.
Late fade	Slightly faster weight through 65%, then a linear slowdown to the finish.	Reserves more time for the final 35%.

Units and Boundaries:

One international mile equals exactly 1.609344 kilometres. Mixed race and marker units are converted before segmentation.
Race distance accepts 0.01 to 200 in the selected unit but is also limited to 200 km-equivalent. Marker spacing accepts 0.01 to 50 in its selected unit and cannot exceed race distance.
The band is limited to 500 marker rows. Stop buffers must leave at least 60 seconds of moving time.
Course allowance is 0% through 3%; shape strength is 0% through 8%; display rounding is 1, 5, or 10 seconds.
The last segment uses the exact remaining official distance, so it may be shorter than the selected marker spacing.

Accuracy Notes:

The arithmetic reconciles the selected assumptions; it does not estimate fitness or predict race-day conditions. Course allowance is a user-entered planning adjustment, not a measurement of the actual line run.

Use official course markers rather than GPS distance when the two disagree.
Compare plans only when distance, marker spacing, allowance, stop buffers, and rounding remain the same.
Slow down, stop, or seek help when symptoms or conditions make the planned pace unsafe.

Worked Examples:

One kilometre at even pace

A 1 km target of 5:00 with markers every 0.5 km, no allowance, and no stop buffer creates two checkpoints. Each half kilometre takes 2:30, so the cumulative rows are 2:30 and 5:00. Changing display rounding cannot alter those full-precision values.

Aid-station time inside a marathon goal

A stop buffer is charged before every marker after the first and before the finish. Adding 10 seconds to a 1 km band therefore reserves time repeatedly, not just once. The finish target stays fixed, so the moving pace becomes faster; check the displayed moving pace before deciding that the buffer is realistic.

References:

NIST Guide to the SI, Appendix B.8, National Institute of Standards and Technology.
Competition and Technical Rules, World Athletics, 2026 edition.