Sport & running
How many seconds per km do super shoes and the drop take off?
A 2–4% pace band when you add or remove a carbon-plate super shoe, and the drop in mm — which does not itself set the seconds per km.
Quick answer
A change of drop is not a pace. Drop is the heel-to-toe difference in millimetres; the seconds per kilometre that lab tests attach to new-generation shoes come from the carbon plate and the foam, and only as a band. The figure most often cited is about 4% better running economy for a plated super shoe against a traditional racing shoe. This page uses 2–4% of your own pace, and only when that plate is added or removed. The 2% is the low side of the same result, for a runner who does not get all of it — not a second measurement, and not a promise. Worked example: 5:00/km is 12.0 km/h, in a 10 mm shoe with no plate. A 6 mm super shoe with a plate is about 6 to 12 seconds per km, so 4:54–4:48/km, about 12.2–12.5 km/h. The 4 mm of drop is written beside that band so you can match the box. It is not what produced the seconds. A road shoe is the one runners call illegal in a World Athletics rankings race when the sole is over 40 mm, it has more than one plate or two plates stacked, or it is a prototype not on sale and not on the approved list. On the track the sole limit is 20 mm. Those shoes can still be bought and trained in. The ban is that start line. The shoe rules in force from 20 April 2026 say so.
Pace band per km
4:48–4:54 /km
- Seconds per km in the band
- about 6–12 s faster
- Speed
- 12.2–12.5 km/h
Drop 10 mm → 6 mm. Those millimetres are not the seconds. This band exists only because a carbon plate and the foam around it came in, or went out. It is a lab range, not your next race. Not legal in a World Athletics road rankings race — the shoes runners call illegal: a sole over 40 mm, more than one plate or two plates stacked, or a prototype that is not on sale and not on the approved list. On the track the sole limit is 20 mm. You can still buy them and train in them. The ban is that start line, not the shop. Shoe rules in force from 20 April 2026.
Just converting the pace? Running pace calculator
2–4% of your pace, and only when you add or remove a carbon-plate super shoe. The 4% is the lab figure most often cited for that kind of shoe against a traditional racing shoe; 2% is the low side of the same band, for runners who do not get all of it. Drop in mm is shown so you can match the box. It is not a seconds-per-millimetre formula, and it is not a reason to change drop for an injury.
How it works
Read the drop off the shoe, then decide whether a plate is in the picture. Zero to 4 mm is a low-drop shoe and puts more work on the calf and the Achilles. Many current super shoes sit around 6–8 mm, with a stack built up toward the 40 mm road-race limit. A daily trainer from the previous generation is often 10–12 mm of drop and a much lower stack. Two shoes can share an 8 mm drop and be different generations: one is foam and a plate, the other is a normal trainer. If both of yours are the same class, the band is about 0 seconds per km. The millimetres still matter for how the leg is loaded. They do not have a measured time.
| Drop | The shoe it usually is | What actually changes |
|---|---|---|
| 0–4 mm | Zero drop or low drop | More load on the calf and Achilles |
| 6–8 mm | Many super shoes | Drop is moderate. The plate is the other number |
| 10–12 mm | Classic daily trainer | The shoe a lot of people trained in a decade ago |
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Frequently asked questions
Does each millimetre of drop take seconds off a kilometre?+
No. Drop is how much higher the heel sits than the forefoot. A 10 mm shoe and a 6 mm shoe can both be ordinary trainers, or one of them can be a super shoe. The lab band on this page — about 2–4% of your pace — turns on only when a carbon plate is added or removed. Change the drop and leave the class alone, and the estimate is about 0 seconds per km.
Is the 2–4% my next race time?+
It is a running-economy band from the lab, not a finish time. The 4% is the figure most often cited for a plated super shoe against a traditional racing shoe; the 2% is the cautious edge of that same figure. Course, weather, fitness and the years between an old race and a new one move the clock by more than the shoe. Two races a long way apart cannot be subtracted down to a shoe.
Why did drop go down while shoes got taller?+
They are two different measurements. Drop is heel minus forefoot. Stack is how tall the shoe is under the foot. New-generation racing shoes grew in stack, up toward the 40 mm road limit, and many of them landed at a smaller drop than the 10–12 mm trainers people used before. Comparing an old time with a new time mixes those two numbers. The one with a lab pace band is the plate and the foam, not the millimetres of drop. Past 40 mm of sole on the road — or 20 mm on the track — the shoe is not legal for a World Athletics rankings race. The same is true of a second plate, two plates stacked, or a prototype that is not on sale and not on the approved list. That is the shoe runners call illegal. It can still be a training shoe. It cannot be the shoe of a rankings result. The rule in force is the one dated 20 April 2026.
Should I lower the drop to fix a calf or Achilles problem?+
This calculator does not choose a drop for an injury. A lower drop shifts load onto the calf and the Achilles; a higher drop shifts it the other way. That is a reason to change gradually if you switch shoes, not a treatment. The seconds on this page are a lab band for a plate, and they stay about 0 when the only thing that changed is the drop.
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