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CalculatorAltitude pace calculator
The same effort is slower at altitude: about 8% in Johannesburg, 5.6% in Pretoria. Type a pace, choose where you train and where you are running, and see the equivalent — for a Joburg runner heading to Cape Town, or a Durban runner racing Soweto.
The same effort as 6:00/km at home, around the country
| Place | Same effort |
|---|---|
| Sea level (0 m) | 5:32/km |
| Durban (8 m) | 5:32/km |
| Cape Town (25 m) | 5:32/km |
| Gqeberha (60 m) | 5:32/km |
| Pietermaritzburg (596 m) | 5:34/km |
| Nelspruit (660 m) | 5:36/km |
| Howick (1 075 m) | 5:45/km |
| Rustenburg (1 160 m) | 5:47/km |
| Polokwane (1 310 m) | 5:50/km |
| Pretoria (1 339 m) | 5:51/km |
| Bloemfontein (1 395 m) | 5:52/km |
| Centurion (1 450 m) | 5:53/km |
| Midrand (1 600 m) | 5:57/km |
Why altitude slows you down
Air pressure falls as you climb, so each breath carries less oxygen to the muscles. The same heart rate and the same effort produce a slower pace. Race Shape slows prescribed paces by roughly 2% for every 300 m above 500 m. That is a planning rule rather than a laboratory measurement — acclimatised athletes lose less — but training to sea-level paces at altitude reliably means training too hard.
Correct for the difference, once
What matters is the difference between where you trained or tested and where you are running. A Johannesburg runner racing the Cape Town Marathon or Two Oceans should expect the same effort to be quicker on the day. A Durban runner racing Soweto should expect it to be slower. Correcting twice — once for where you trained and again for where you race — is the error most tools make.
Racing low after training high
The trap for Gauteng runners at the coast is the first 5 km. Your coastal-equivalent pace feels easy, so you go out at it and beyond, and the debt arrives at 30 km. Use the converted pace as a ceiling for the first third, then hold or lift. Heart rate is a useful cross-check: in the first days after travelling up, it runs high at paces that normally feel easy.
Common questions
How much slower is running in Johannesburg?
About 8% at 1 753 m for the same effort: a 6:19/km easy pace at the coast is about 6:51/km in Johannesburg.
Will I be faster racing at the coast?
If you live and train at altitude, yes — the same effort produces a quicker pace at sea level. Start no faster than your converted pace and let the second half be the quick one.
How long does it take to acclimatise to altitude?
Some adaptation starts within days, but meaningful adaptation takes weeks. A weekend trip does not acclimatise you.
Does altitude affect cycling power too?
Yes. Power drops by roughly 6% per 1 000 m above 500 m, less for a rider who lives at altitude. Cycling power zones.
Put this calculator on your club’s website
Free for running clubs, coaches, race organisers and bloggers. Copy the code below into any page that accepts HTML — WordPress, Wix and Squarespace all do — and your members get the same live altitude pace calculator, with nothing to install and no sign-up.
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Related
- How altitude affects running pace
- Training pace calculator
- Running plans in Johannesburg
- All calculators
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