Swim Split Calculator

Per-100m pace · per-length splits · triathlon finish times · pool or open water

metres
Swim Time
hrs
min
sec
Environment
Pool Length
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pace per 100m
Enter distance and time
Triathlon Projections
Sprint — 750m
Olympic — 1500m
70.3 — 1900m
Ironman — 3800m
Per-Length Splits
Length Distance Split Cumulative
Enter distance and time to see splits
Finish Times at Current Pace
Distance Pool Finish Open Water (+5%) Pace / 100m
Enter a swim time on the Calculator tab first

Formula

Pace = Total Time ÷ (Distance ÷ 100)
Open Water = Pool Pace × 1.05
Finish Time = (Distance ÷ 100) × Pace/100m

Frequently Asked Questions

What is a good 100m swim pace?

For recreational swimmers, 2:00–2:30/100m is a solid baseline. Intermediate swimmers typically hold 1:30–2:00/100m. Competitive age-groupers aim for 1:10–1:30/100m. Elite open-water triathletes race near 1:00–1:10/100m. For triathlon context: finishing an Ironman swim (3800m) in under 70 minutes requires approximately 1:50/100m.

How much slower is open water swimming vs pool?

Open water swimming is typically 5–10% slower than pool swimming. The standard adjustment used in triathlon planning is +5% — meaning a 1:30/100m pool pace becomes roughly 1:34/100m in open water. The difference comes from navigation (sighting), chop, currents, lack of wall push-offs, and wetsuit buoyancy effects (which can partially offset the slowdown).

How should I pace my triathlon swim?

Start slightly conservative for the first 200–300m to avoid blowing up in the chaos of a mass swim start. Settle into your target pace for the middle portion. Save a slight surge for the final 100–200m. For most age-groupers, a consistent even-paced effort beats going out hard — the bike and run are what win triathlons, and an aerobic swim effort preserves energy for both.

How many pool lengths is a triathlon swim?

In a 25-metre pool: Sprint Tri (750m) = 30 lengths, Olympic Tri (1500m) = 60 lengths, 70.3 Ironman (1900m) = 76 lengths, Ironman (3800m) = 152 lengths. In a 50-metre (Olympic) pool: Sprint = 15 lengths, Olympic = 30 lengths, 70.3 = 38 lengths, Ironman = 76 lengths.

What swim pace do I need for a sub-1-hour Ironman swim?

To swim 3800m in under 60 minutes, you need a pace faster than 1:34/100m in open water (approximately 1:30/100m pool-equivalent). This is a strong but achievable goal for dedicated age-group triathletes. Most Ironman age-groupers finish the swim in 65–85 minutes, requiring a pace of 1:42–2:14/100m.