Find your pace per 100m/yd and get all 6 training zones for smarter swim workouts.
| Zone | Name | Effort | Pace Range (per 100) | Purpose |
|---|
| Distance | Target Time | Rest (β10%) |
|---|
Choose Pace from Swim to enter a distance and time you've actually swum β the tool calculates your pace per 100m or 100yd automatically. Or choose CSS (Threshold Pace) to enter your known Critical Swim Speed directly. Hit Calculate to see all six training zones.
Training without structure is one of the biggest mistakes swimmers make at every level. A recreational swimmer churning out 30 laps at the same moderate effort every session will plateau within weeks. A structured approach using training zones changes everything.
Zones 1β2 build your aerobic base and teach your body to use fat as fuel β essential for triathletes and open-water swimmers. Zone 3 (tempo) improves your lactate threshold, the key driver of sustained speed. Zone 4 (threshold/CSS) is where most performance gains happen for competitive swimmers β intervals at this pace with short rest are the bread and butter of elite squad training. Zones 5β6 develop raw speed and VO2max, critical for 50β200m racers.
A common example: a 1:50/100m swimmer doing threshold sets (Zone 4) with 10-second rests turns a 400m swim from a slog into a structured workout with measurable improvement week over week. Knowing your zones means every metre you swim has a purpose.
Pace: Total seconds Γ· (Distance Γ· 100) = seconds per 100m or yd.
Training zones are derived from your threshold pace (CSS), using widely-accepted percentage multipliers:
Higher pace values (more seconds) = slower swimming. Zone 1 has the highest seconds/100 value.
CSS is the theoretical maximum pace you could sustain indefinitely without accumulating lactate β in practice it's your ~1,500m race pace for trained swimmers. It's the gold-standard threshold marker for swim training. You calculate it by comparing your 400m and 200m all-out time trial results.
Train in whatever unit your pool uses. Most 25m and 50m pools worldwide use metres; most US pools are 25-yard courses. The pace difference is small (~9%) but meaningful β always specify your unit to avoid incorrect zone targets. This calculator supports both.
They're based on well-established percentage ranges used by coaches worldwide, but individual physiology varies. If a zone feels too easy or too hard after a few sessions, adjust by 3β5 seconds per 100 in the appropriate direction. Heart-rate and RPE data alongside pace gives the most complete picture.
Yes β enter your GPS-tracked open-water pace (distance and time) into the calculator. Bear in mind that open-water pace is typically 5β10% slower than pool pace due to sighting, turns, and current. Your zones will still be valid as relative targets for OWS training.