Pace & Speed Converter

Pace-Speed Conversion

{{ paceReadable || '—' }} = {{ speedReadable || '—' }}

Pace:

Format is minutes + seconds, e.g. 5 and 00 for 5:00 per selected road unit.

Speed:

Use values such as 12.0 km/h or 7.5 mph; unit selection syncs the pace basis.

Distance:

Enter race or session distance in the active road unit; 0 hides planning rows.

Split distance:

Use 1 km/mi for race splits or 400 m for track-style checkpoints; minimum 0.01.

Projection profile:

Balanced 1.06, endurance 1.04, speed 1.08; compare profiles when distance changes.

Goal distance:

Enter a positive race distance, for example 21.0975 km or 13.1 mi.

View	Current	Notes	Copy
{{ row.label }}	{{ row.current }}	{{ row.notes }}

Metric	Value	Copy
{{ row.label }}	{{ row.value }}

Marker	Clock	Remaining	Copy
{{ marker.label }}	{{ marker.clock }}	{{ marker.remaining }}

Topic	Details	Copy
{{ note.title }}	{{ note.text }}

Checkpoint	Distance	Split Time	Cumulative	Remaining	Progress	Copy
{{ s.label }}	{{ s.splitDistance }}	{{ s.splitTime }}	{{ s.cumulativeTime }}	{{ s.remainingTime }}	{{ s.progress }}
No split ladder yet Add a distance and keep a valid pace or speed input to build the pacing ladder.

Race	Distance	Projected Time	Projected Pace	Projected Speed	Vs Current Pace	Copy
{{ row.race }}	{{ row.distance }}	{{ row.projectedTime }}	{{ row.pace }}	{{ row.speed }}	{{ row.paceDelta }}
No projection ladder yet Add a distance to generate equivalent race projections from the current pace-speed conversion.

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Running pace and running speed describe the same effort in two different languages. Pace tells you how long one kilometre or one mile takes. Speed tells you how much distance you cover in an hour. Most runners move between both views all the time, especially when training outdoors by pace and then checking a treadmill by km/h or mph.

This calculator starts with either side of that pair. Enter a pace and it returns the matching speed. Enter a speed and it returns the matching pace. If you also add a distance, the same effort turns into a finish time, major course markers, a full split ladder, and equivalent-race estimates across common target events.

That makes the page useful for several practical jobs. You can check whether a goal pace matches the treadmill setting you need. You can see what a chosen effort means over 10 km, 10 miles, a half marathon, or a marathon. You can also export the result as CSV, DOCX, chart images, or JSON when you want to drop the numbers into a workout sheet, notes app, or downstream planning workflow.

The output is layered on purpose. Effort Snapshot and Conversion Table give the raw conversion. Course Markers and Split Ladder turn that average effort into checkpoints. Race Projection Ladder applies a Riegel-style distance model with fixed profiles. Pace-Speed Map adds a visual view of the current effort instead of another table.

It also helps to be clear about what kind of answer each part gives. The pace-speed conversion and finish time are direct arithmetic once the inputs are valid. The race-projection rows are estimates built from a distance model, so they are best used as planning guidance rather than a guarantee, especially when the jump to the goal race is large.

Technical Details

The calculation starts with the reciprocal link between pace and speed. If you know the seconds needed to cover one kilometre, speed is simply 3600 divided by that value. If you know speed in km/h, pace is the same relationship turned over. The same logic applies in miles after unit conversion. Because the page keeps the underlying effort normalized, switching between kilometre and mile views does not create a new run. It only changes how the same run is expressed.

Distance is optional, but once it is present the calculator multiplies normalized pace by normalized distance to get elapsed time. That shared time value then feeds the marker rows, split rows, and projection ladder. Split spacing can match the current road unit, switch to the other road unit, or use metres when you want short interval-style checkpoints.

One valid pace-speed pair becomes the shared baseline for every other view. Distance adds finish-time context, and the projection settings branch into equivalent-race estimates.

\begin{array}{lcl} p_{km} & = & \frac{T}{D_{km}} \\ v_{km/h} & = & \frac{3600}{p_{km}} \\ T finish & = & p_{km} \times D_{km} \\ T goal & = & T ref \times {(\frac{D_{goal}}{D_{ref}})}^{e} \end{array}

The projection ladder uses three fixed Riegel exponents: 1.04 for an endurance-leaning profile, 1.06 for a balanced profile, and 1.08 for a speed-leaning profile. Lower values hold pace better over longer distances. Higher values assume more slowdown. The table includes standard targets such as 5K, 10K, 10 miles, half marathon, marathon, and one custom goal distance.

The chart is deliberately relative. Pace-Speed Map draws a curve around the current effort, marks the current point, and shades pace bands labelled Race push, Target pace, Steady effort, and Easy / recovery. Those bands are generated from the current pace rather than from an external coaching system, so they help orientation but should not be mistaken for universal training zones.

How each major output is produced
Output	What the calculator uses	What you can do with it
`Effort Snapshot` and `Conversion Table`	The current pace-speed pair, active unit system, and optional distance context.	Check the core conversion before trusting any planning view.
`Course Markers`	The current finish time plus fixed reference points at `25%`, `50%`, `75%`, and, when possible, the start of the final `1 km` or `1 mi`.	Read broad pacing checkpoints without scanning every split row.
`Split Ladder`	The current finish time and the chosen split interval, with cumulative time, remaining time, and progress at each checkpoint.	Build a race band, interval card, or treadmill checkpoint list.
`Race Projection Ladder`	Reference time, reference distance, goal distance, and the selected Riegel exponent.	Compare nearby and longer target races from the same reference effort.
`Pace-Speed Map` and exports	The live pace-speed pair plus derived chart data. All calculations, chart data, and JSON are produced in the browser.	Keep data local, download chart images or CSV, and export structured values for later reuse.

Standard unit relationships and official road-race distances matter here because they anchor the calculator's arithmetic. The mile-to-kilometre conversion follows the international mile used in NIST guidance, and the half marathon and marathon distances match the official World Athletics event lengths.

Everyday Use & Decision Guide

If your only question is conversion, keep the workflow short. Enter pace or speed, leave distance empty, and read Effort Snapshot first. That view gives the fastest confirmation that the two numbers match. Conversion Table is the next stop when you want the alternate road unit, the alternate speed unit, or a quick check of the primary metrics in one list.

The page becomes more valuable when you add distance. A road runner can turn a target half-marathon pace into a finish time and then see both kilometre and mile implications. A treadmill user can start with mph, switch to the mile system, and still check the equivalent pace per kilometre before heading outside. A coach can keep the same reference effort while changing only the split interval to produce session notes at 400 m, 1 km, or 1 mi spacing.

Course Markers and Split Ladder serve different planning styles. Use markers when you want only the big checkpoints, such as halfway or the start of the final kilometre. Use the split table when you need the whole ladder with cumulative time, remaining time, and progress percentage. The split table is especially useful when the chosen interval matches how you expect to receive feedback during the run.

Pacing Notes is the quickest summary panel once the calculation is valid. It condenses the current state into short prompts about unit choice, distance context, split density, and projection stretch. That makes it a good final glance after you have checked the numbers but before you export them.

Use the projection ladder with more restraint than the raw conversion. When the goal race is close to the reference distance, the projection often behaves like a reasonable extension of the current effort. When the goal race is much shorter or much longer, the choice of projection profile matters more, and the result should be treated as a range-setting aid rather than a promise.

Step-by-Step Guide

Enter either a pace or a speed. The matching value updates automatically in the current unit system.
Choose kilometres or miles depending on how you normally think about road pace. The page converts the whole reference effort when you switch systems.
Open Advanced and add a distance if you want finish time, markers, splits, or equivalent-race projections.
Set a split interval that matches how you want to monitor the run. Road units work well for races, while metres are useful for short repeats.
Pick a projection profile and goal distance only after the base conversion looks right.
Read Effort Snapshot and Conversion Table before moving deeper. If those numbers look wrong, fix the inputs first.
Use Course Markers, Split Ladder, and Race Projection Ladder according to the level of detail you need.
Download CSV, DOCX, chart files, or JSON when you want to carry the result into another document or workflow.

A simple rule helps here: change one thing at a time. Keep the same reference effort while you compare unit systems, split sizes, or projection profiles so the difference you see stays easy to explain.

Interpreting Results

The most literal answers are the conversion rows. Pace (per km), Pace (per mile), Speed (km/h), and Speed (mph) are all direct restatements of the same effort. If your question is simply "what pace equals this treadmill speed?" or "what speed equals this goal pace?" those rows are the main result.

Finish time, markers, and split rows are still arithmetic, but now they assume the same average effort is carried across the full distance. That is why they are good planning aids and not a race simulation. The page does not add surges, fade, hills, weather, or fueling problems. It shows the clocks you would hit if the average pace stayed on track.

The projection ladder deserves a more cautious reading. The Riegel relationship is widely used for distance-based race prediction, but evidence in recreational runners suggests it behaves more reasonably up to the half-marathon range than it does for the marathon, where plain distance-only prediction tends to be less well calibrated. When the projected marathon shifts sharply between 1.04, 1.06, and 1.08, the right lesson is usually to widen your pacing margin rather than pick the fastest row.

The chart should be read as a quick visual orientation layer. Faster pace values appear higher because the pace axis is inverted, and the shaded bands are built around the current effort, not around a universal rule set. It is useful for spotting where the current point sits relative to nearby faster and slower efforts, but the actual target numbers should still come from the tables.

How to interpret each output safely
View	Best use	Main caution
`Effort Snapshot`	Quick trust check for the live pace-speed pair.	It does not show how the effort plays out over distance until distance is added.
`Course Markers`	Broad checkpoints such as halfway and late-race timing cues.	Markers still assume even average pacing.
`Split Ladder`	Detailed pacing plan with split, cumulative, remaining, and progress columns.	Very small split sizes create many rows and can make the ladder harder to use in practice.
`Race Projection Ladder`	Comparing how one effort maps to nearby or longer target races.	Profile choice matters more as the distance gap grows, especially toward the marathon.
`Pace-Speed Map`	Seeing the current effort in relation to faster and slower nearby ranges.	The shaded bands are relative labels, not formal coaching prescriptions.

Worked Examples

Turning a steady 10 km pace into a full checkpoint plan

Enter 05:00 / km and set distance to 10 km. The calculator returns 12.00 km/h and a finish time of 00:50:00. In Course Markers, the quarter mark lands at 00:12:30, halfway at 00:25:00, and the start of the final kilometre at 00:45:00.

That is a clean example of when the arithmetic views do most of the work. Nothing is being predicted beyond the chosen effort. The output simply translates one average pace into clocks you can follow.

Starting from treadmill speed and checking the road pace

Enter a speed of 8.00 mph and set distance to 10 miles. The matching pace is 07:30 / mile, which is about 12.87 km/h in the alternate system, and the finish time comes out to 01:15:00.

This is a useful cross-check when the machine shows speed but your race plan is written in pace. The conversion answers the unit question immediately, and the distance context shows whether the target is realistic for the session length you have in mind.

Seeing how the projection profile changes a marathon estimate

Use a reference effort of 10 km in 00:50:00 and compare the marathon row across profiles. The endurance-leaning profile gives about 03:43:29. The balanced profile gives about 03:50:01. The speed-leaning profile gives about 03:56:44.

The important takeaway is not which row looks nicest. It is the spread. When a longer-distance estimate moves by several minutes just from the exponent choice, that distance jump is large enough that you should treat the projection as pacing context, not as a single definitive forecast.

FAQ:

Should I enter pace or speed first?

Use whichever view matches the way the effort was measured. Road plans often start with pace, while treadmills often start with speed. The calculator keeps both views synchronized.

Why do several values change when I switch from kilometres to miles?

Because the page converts the whole effort, not just the label. Pace, speed, and distance all move together so the underlying run stays the same.

Does changing split size change the finish time?

No. Split size only changes how often the same finish time is broken into checkpoints.

Why do projection results feel less trustworthy for very long jumps?

Because the model only knows the reference performance and the distance relationship. As the goal race moves farther away, unmodeled factors such as durability, fueling, terrain, and pacing discipline matter more.

Why do very tiny split intervals stop producing endless rows?

The calculator limits intermediate split rows so the table remains usable. If you need a denser breakdown, export the JSON and continue from the structured data.

Does my data stay local?

Yes. The calculator keeps the pace conversion, finish-time math, chart data, exports, and JSON generation in the browser after the page loads.

Glossary:

Average pace: Time needed to cover one unit of distance, shown here as minutes per kilometre or minutes per mile.
Average speed: Distance covered per hour, shown here as kilometres per hour or miles per hour.
Split interval: The chosen checkpoint spacing used to build the split ladder, either in kilometres, miles, or metres.
Projection profile: The selected Riegel exponent that controls how strongly time rises as distance changes.
Pace delta: The projected pace difference versus the current reference pace shown in the race-projection ladder.

References:

NIST Guide to the SI, Appendix B: Conversion Factors, National Institute of Standards and Technology.
Half Marathon, World Athletics.
Marathon, World Athletics.
Athletic Records and Human Endurance, American Scientist, 1981.
An empirical study of race times in recreational endurance runners, BMC Sports Science, Medicine and Rehabilitation, 2016.