Sweat Rate & Hydration Calculator

Why do we need to know our sweat Rate?

Dehydration in sport can lead to:

  • Cramping
  • Reduced endurance capacity
  • Reduced strength and power
  • Impaired skill execution and concentration
  • Impaired decision making capacity
  • Increased injury risk

In order to prevent the decline in performance we must hydrate well.


This simple sweat test can be done at home and calculates your sweat loss per hour. You should concentrate on replacing this amount of fluid during training and competition.

What should I be Aiming For?

Aim to limit your percentage dehydration to 1% during racing/competition.

For ultra endurance events, aim to limit your percentage dehydration to 2% over the race.

The sweat Rate Calculator


  1. Choose a training session where you will be training at race pace, in a similar climate to your race climate (where possible) and for a duration of at least 1 hour.
  2. Use accurate scale to the nearest 0.1 – 0.01 kg.
  3. Weigh yourself before training with no clothes on.
  4. Weigh your water bottles prior to training.
  5. Train at race pace for 1hr or more  and record the amount of time that you trained for.
  6. Remove all clothing and towel dry the sweat from your body.
  7. After training, weigh yourself again and weigh your water bottles separately.


Total Sweat Loss: L

Percentage Dehydration: %

Sweat Loss Per Hour: millilitres / hour

Still having problems?

If you are hydrating well and still experiencing cramping, fatigue or poor performance then you may need help improving your:

  • Pre-training/competition nutrition
  • During training/competition nutrition
  • Recovery nutrition
  • Electrolyte balance
  • Mineral status

Get in touch to book an online or in-clinic sports nutrition consultation to maximise your performance.

  • 0490 876 451