Swimming SWOLF & Stroke Efficiency Calculator - Measure Hydrodynamic Speed per Pull
Combine lap time and stroke count into a unified SWOLF index to swim faster with less drag and lower heart rate.
How to Use Swim SWOLF Calculator in 3 Simple Steps
Step 1: Upload
Drag & drop your .FIT, .GPX, or .TCX activity file. All processing is 100% private in your browser.
Step 2: Process
FitCrop inspects telemetry streams, removes anomalies, recalibrates metrics, or fixes binary checksums.
Step 3: Export
Download your clean Strava, Garmin, and Zwift compatible file with 1 click. Zero server wait.
Frequently Asked Questions
What is a good SWOLF score in a 25m pool?
A score under 35 in a 25m pool indicates advanced swimming efficiency. Elite swimmers routinely score under 30.
How is SWOLF calculated?
SWOLF is the sum of time in seconds plus the number of arm strokes taken to complete one pool length.