ITRA Km-Effort Calculator
Calculate the official ITRA km-effort and distance category of any trail race. Free, instant, no account needed.
Result
How Km-Effort Is Calculated
This is ITRA's (International Trail Running Association) official, unmodified formula: km-effort = distance (km) + D+ (m) / 100. For example, a 40km route with 2,500m of D+ equals 40 + 25 = 65 km-effort. ITRA uses this figure to sort races into seven categories, from XXS (under 25) to XXL (210 and up). This differs from the km-effort shown on our GPX Explorer tool, which deliberately adds a descent term to reflect the real muscle load of steep descents — the figure shown here is ITRA's own, unmodified formula.
Frequently Asked Questions
What is km-effort?
It's a difficulty unit ITRA uses to compare races with different distance/elevation combinations on an equivalent scale. 100m of elevation gain is treated as roughly equivalent to 1km on flat ground.
Why does my km-effort differ from another calculator's number?
Some calculators (including our own GPX Explorer tool) use extended formulas that also account for descent. This tool shows ITRA's official, climb-only formula.
What do the ITRA categories mean?
Seven categories, from XXS (very short, low-elevation races) to XXL (very long, high-elevation ultras), indicate a race's overall difficulty/size class.