Open water swim time

Start from your pool pace, add a wetsuit and an allowance for open water conditions to see how long your swim will take.

Your details

1,500 m in open water

30:29

estimated swim time

Same distance in the pool30:00
Wetsuitabout 3% quicker
Your open water allowance5% slower
Open water pace2:02 per 100 m

Water under 15°C can trigger cold water shock: get in slowly, let your breathing settle, and keep the first swims short. Sighting, waves and no walls to push off all cost time. Swim with others, wear a bright hat and use a tow float.

In an emergency on or near water, call 999 or 112 and ask for the Coastguard. If you fall in, Float to Live: lean back, ears under, until your breathing settles.

The working

1,500 m at 2:00 per 100 m

In the pool that is 30:00. A wetsuit made swimmers about 3.2% faster over 1,500 m in one study, and a 5% open water allowance adds time back: 30:29, or about 2:02 per 100 m.

Why open water is slower

And sometimes faster

Factor	Effect
No walls to push off	slower
Sighting every few strokes	slower
Waves and currents	slower or faster
Wetsuit buoyancy	faster
Drafting another swimmer	faster

Staying safe

Every time

Swim with others or at a lifeguarded venue
Bright hat and a tow float
Get in slowly and let your breathing settle
Know how you will get out before you get in

Read with care

What this cannot tell you

ConditionsTides and wind can change a swim by minutes.
Your allowanceUse your own number once you have done a few open water swims.
ColdCold water slows everyone and can be dangerous.

Questions

Common questions

Is open water swimming slower than pool?

Usually, because there are no walls and you need to sight, though a wetsuit can make up some of it.

How much faster is a wetsuit?

One study found about 5% over 400 m and 3% over 1,500 m. Leaner swimmers gained more.

What is cold water shock?

A gasp and fast breathing when you enter water under 15°C. It passes in under a minute if you float and wait.

Sources

Last checked 21 October 2026. Spotted something wrong? Tell us and we will fix it.

Before you push on

New to exercise, or got a heart, lung or joint condition? Have a word with your GP or practice nurse first. Stop and get help if you feel chest pain, faintness or unusual breathlessness, and call 999 if it is severe.