PB predictor

How long will my race take on this course?

Enter a recent result and the race you are targeting. We convert your current form to an equivalent finish time, then apply the target course's GAP factor when verified geometry is available.

Fastest 10k courses in the current model

• Bozeman Half Marathon & 10K

  GAP -5.3%.

• La Jolla Half Marathon, 10K & 5K

  GAP -4.5%.

• St. Croix Crossing Half Marathon 10K

  GAP -3.3%.

• Montana Marathon (Billings) 10K

  GAP -2.6%.

• RAD Half Marathon & 10K (Asheville)

  GAP -2.3%.

• Generali Genève Marathon 10K

  GAP -1.3%.

• Zurich Rock 'n' Roll Running Series Madrid 10K

  GAP -0.8%.

• Bay of Fundy International Marathon 10K

  GAP -0.8%.

Why a course-adjusted predictor

Generic predictors assume every course is flat. When a race has a verified GAP profile, this tool uses that measured gradient profile so a target with 300 m of climb is predicted slower than a pancake-flat PB course.

See the gradient-normalisation methodology →

Find a course that suits your target

• Flattest marathons

  Courses with the lowest GAP penalty in our gradient model.