De formule
How to calculate halve marathon tempo
Tempo is hoe lang elke mijl gemiddeld duurt over de hele run, gevonden door de totale tijd te delen door de totale afstand. Het is het getal waarop de meeste trainingsschema's en wedstrijdvoorspellingen zijn gebaseerd, in plaats van de totale eindtijd.
Een halve marathon van 2 uur komt uit op 9,16 minuten per mijl — maar die 0,16 is 16% van een minuut, ongeveer 10 seconden, niet 16 seconden, omdat de uitvoer decimale minuten is en geen minuten en seconden.
What to enter:
- Afstand (miles) — de standaard halve marathonafstand is 13,1 mijl (21,1 km)
- Eindtijd (minutes) — reken uren eerst om naar minuten, bijvoorbeeld 2 uur 5 minuten = 125
Results appear immediately — there is nothing to submit. Changing a field rewrites the link, so you can share the exact scenario you are looking at.
If an exact figure for one of the fields is not available, a careful estimate is a reasonable starting point, since the calculator recomputes instantly the moment a more accurate number is available — nothing here depends on getting every field exact on the first pass.
Why halve marathon tempo matters
People usually look up a halve marathon tempo calculation to put a number on something they can already sense but cannot quite quantify — how their fitness compares with a reference range, how a measurement is trending, or what a change actually means. A calculator turns that vague sense into a concrete figure, which is useful even though the figure itself is only ever an estimate.
This tends to get checked before or after a change in routine — a new training block, a change in diet, a different stage of a pregnancy — as a way of putting a figure on something that would otherwise only be felt rather than measured.
It is also worth being honest about what a formula like this is actually built from. Most of the equations behind calculators like this one were derived from population studies — averages taken across large groups of people — and applied here as a general-purpose estimate rather than a measurement tailored to any one individual. That is a reasonable trade-off for a quick, free estimate, and it is also exactly why a result that looks unusual is worth discussing with a professional rather than acted on alone.
In practice, this kind of figure is often calculated more than once with slightly different inputs to see how sensitive it is — trying a measurement taken this morning against one taken yesterday evening, for instance, to see how much normal daily variation actually moves the result. That habit is a good one: it builds a feel for how much a single reading can be trusted on its own before drawing any conclusion from it.
Worked example
Work through the defaults on this page:
- Afstand: 13.1 miles
- Eindtijd: 120 minutes
That gives:
- Gemiddeld tempo: 9.16 min/mile
Those starting figures exist only to show the calculation working, not as a target or a reference value to compare yourself against — replace them with your own measurements in the calculator above and the same formula applies exactly as shown.
Reading the result
Sub-8:00/mijl is een sterk clublopers-tempo voor de afstand; 10:00-11:00/mijl dekt een groot deel van de finishers. Vergelijk het met een recent 10 km-tempo: halve marathontempo ligt doorgaans 10-20 seconden per mijl langzamer.
Where this goes wrong. De decimale uitvoer is makkelijk verkeerd te lezen als minuten en seconden — 9,5 betekent 9 minuten 30 seconden, niet 9 minuten 5 seconden. Vermenigvuldig het decimale deel met 60 om het naar seconden om te rekenen.
As with any general-purpose formula, the result here is an estimate derived from population averages, not a measurement specific to you — a reasonable starting point for a conversation with a qualified professional, not a replacement for one. Nothing on this page is medical advice.
Ongeveer 11:00-13:00 per mijl is een veelvoorkomend realistisch doel voor een eerste halve marathon, met een finishtijd van ongeveer 2:25-2:50. Tempo is minder belangrijk dan comfortabel finishen bij een eerste poging.
Vermenigvuldig minuten per mijl met 0,621, of deel door 1,609. Een tempo van 9:00/mijl komt uit op ongeveer 5:36/km.
The headline figure is gemiddeld tempo. With 13.1 miles afstand and 120 minutes eindtijd, that comes to 9.16 min/mile. Change any field and the figure moves with it.
It uses a published formula applied exactly as defined, so the arithmetic itself is precise — but the formula is a population-level estimate, and individual results can vary from it for reasons the formula has no way to account for. Treat the output as a reasonable estimate rather than a measured or diagnostic value.
For most people, yes — a single reading is a snapshot, while the same measurement repeated consistently over weeks or months shows a trend, which is generally more informative than any one figure taken in isolation.
Small differences between calculators usually come down to which published formula or reference dataset each one uses — several equations in this area exist in more than one accepted version. This page states the specific formula used in the section above, so it is possible to check directly whether another source is using the same one.