Open Water Swim Pace Calculator

How much slower is open water swimming than pool swimming?

Without a wetsuit, open water swimming is typically 5–15% slower than pool pace at the same effort. The main reasons are sighting (lifting your head to navigate costs 3–10 seconds per 100m), absence of wall push-offs, water conditions, and navigational inefficiency. With a well-fitted wetsuit, the buoyancy advantage can offset most of these factors, making wetsuit open water pace comparable to or faster than pool pace for many swimmers.

How much faster does a wetsuit make you in open water?

A standard triathlon wetsuit typically improves open water pace by 8–15 seconds per 100m compared to swimming without one. The improvement comes from increased buoyancy (higher body position reduces drag), warmth (allowing better muscle function), and the psychological confidence of feeling more supported in the water. Racing wetsuits with thinner arms offer slightly more improvement due to reduced shoulder restriction.

What is sighting in open water swimming?

Sighting is the technique of lifting your head during freestyle to look forward and navigate toward a buoy or landmark. It is necessary in open water where you cannot follow a lane line. Each sighting action causes a slight body position drop that costs 3–8 seconds per 100m depending on how often you sight and your technique. Experienced swimmers minimise this by sighting every 15–20 strokes using a brief forward glance rather than a full head lift.

How do I calculate my open water swim time for a triathlon?

Start with your pool pace per 100m. Add adjustments for sighting (+3–10 sec/100m), water conditions (+0–25 sec/100m), and subtract the wetsuit advantage if wearing one (−8–15 sec/100m). Multiply your adjusted pace by the distance in 100m units. For example: 2:00/100m pool pace + 6s sighting + 8s chop − 12s wetsuit = 2:02/100m open water pace × 19 (for 1900m) = 38:38.

Does current affect open water swim time significantly?

Yes. A moderate favourable current (river, tidal) can reduce swim time by 10–25 seconds per 100m — saving several minutes on a triathlon swim. Swimming against current adds the same penalty. Most triathlon courses are designed as loops to neutralise current effects, but point-to-point open water races can be significantly affected. Check race conditions and course map before estimating your time.

What water temperature requires a wetsuit?

World Triathlon (ITU) rules require wetsuits when water temperature is below 16°C (61°F) and prohibit them above 22°C (72°F). Between 16°C and 22°C, wetsuits are optional. Ironman events follow similar rules with slight variations. Below 16°C, a wetsuit is strongly recommended for safety regardless of rules. Water temperature also affects performance — cold water (below 18°C) can cause significant muscle efficiency reduction.

How can I improve my open water swimming?

The biggest improvements come from practising sighting technique (reduces the pace penalty significantly), swimming in open water regularly before racing (reduces navigation anxiety and improves confidence), drafting behind other swimmers (reduces energy cost by 15–20%), and starting in a position that matches your pace to avoid early congestion. Pool fitness is necessary but not sufficient — open water specific skills are learned only in open water.

Is a 1500m open water swim hard?

A 1500m open water swim is the Olympic triathlon distance. For a swimmer with consistent pool training (3–4 sessions per week), it is comfortably achievable. With a wetsuit in calm conditions, most recreational swimmers who can complete 1500m continuously in a pool will finish the open water distance in 25–40 minutes. Without a wetsuit in choppy conditions, expect 5–10 minutes longer than your pool time.