Free tools · No login required

Training Stress Score Calculator

TSS and Intensity Factor for any cycling or running session

Calculators

LT1/LT2

Lactate Analysis

7-zone

Power Zones

Free

Forever

Training Load (TSS)

Calculate Training Stress Score and Intensity Factor for any session

Duration (hours)

Duration (minutes)

Normalized Power / avg (W)

Your FTP (W)

Lactate Analysis

LT1, LT2, OBLA from blood lactate step tests

Progress Tracking

Track fitness trends across weeks and months

Training Zones

7-zone power, HR and pace zones for every sport

Coach Tools

Manage multiple athletes and share test reports

LaChart combines lactate testing, training analytics, Strava sync and coach collaboration in one platform.