GP Bern Forecast
GP Bern time (10 miles) → forecast for all distances
GP Bern time (10 miles, 16.1 km)
Flat equivalent (without the 204 m of climbing): 1:09:02 · VDOT: 49.6
Forecast via Riegel formula (exponent 1.06)
From the Grand Prix to every other distance
The Grand Prix of Bern runs over ten miles, just over 16 kilometres, and is one of Switzerland's largest running events. Many runners have a recent, genuinely raced time from it.
That makes a good starting point: the calculator estimates what would be possible over five or ten kilometres, a half marathon or a marathon.
How it is calculated
Step one: flat time = GP Bern time / 1.014. The factor comes from Minetti's energy cost for the course's 204 m of climbing and 201 m of descent (assumed at an average grade of 4 %): going up costs more than coming down saves. Step two: prediction = flat time × (target distance / 16.093)^1.06 — the Riegel formula with the Grand Prix's 10 miles as the base. VDOT comes from the flat time, following Jack Daniels.
The exponent 1.06 describes how pace fades with distance; for the GP that gives factors of 0.290 for 5 km, 0.604 for 10 km, 1.332 for the half marathon and 2.778 for the marathon.
Example: 1:10:00 = 4200 s. Flat time = 4200 / 1.014 = 4142 s = 1:09:02. 5 km = 4142 × 0.290 = 1200 s = 20:00. 10 km = 4142 × 0.604 = 2501 s = 41:41. Half marathon = 4142 × 1.332 = 5519 s = 1:31:59. Marathon = 4142 × 2.778 = 11507 s = 3:11:47. VDOT = 49.6.
The elevation correction is an estimate without the exact profile; since the last 1.5 km in Bern are steep, the real course probably costs a little more than 1.4 % — so the prediction stays on the cautious side.
If you calculate a marathon time from your GP Bern result, treat it as an upper bound: the jump from 16 to 42 km is large, and the formula knows nothing about your long-run training.
What to keep in mind
The Bern course is not flat. A time set there came on rolling terrain — on a flat course a little more would be possible.
For longer distances the usual caveat applies: the prediction assumes you have trained for them.
Frequently asked questions
- Does this only work with a GP Bern time?
- No. Any seriously raced ten-kilometre time works; Bern is simply the most common occasion.
- How reliable is the marathon prediction?
- It tends to be optimistic. Being fast over ten kilometres without ever running long will not get you there.
- What is the VDOT value shown?
- A measure of your running form that training paces can be derived from. The VDOT calculator explains more.