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 marathon courses in the current model

• Estes Park Marathon and Half Marathon

  GAP -4.6%.

• Montana Marathon (Billings)

  GAP -2.5%.

• Windermere Marathon (Spokane)

  GAP -0.5%.

• Reims Champagne Run Marathon

  GAP -0.4%.

• Maratona do Funchal (Funchal Marathon)

  GAP -0.4%.

• Generali Genève Marathon

  GAP -0.3%.

• Belfast City Marathon

  GAP -0.1%.

• Hoag OC Marathon Running Festival

  GAP -0.1%.

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.