WHY IS YOUR SWEAT SALTY AND HOW MUCH SALT ARE YOU ACTUALLY LOSING?

October 26, 2026

Written by Jessica Jackson

Welcome to the first installment of the Hydration Edit, where we chat about how hydration actually works: what’s going on with your body, what the research says, and what that really means day-to-day for you. To kick us off, we’re starting with salty sweat.

You might trickle it or pour it, but how much sodium are you actually losing when you sweat?

Spoiler: it depends.

Sweat sodium concentration varies considerably from person to person. And your personal physiology plays a big role too. Factors like exercise conditions and heat acclimatisation can also influence how salty your sweat is.

But here’s what actually sets the number, and how to work out which end of the range you could be on.

Signs you’re a salty sweater

You might already have an inkling of whether you’re a salty sweater or not, especially if any of these sound familiar:

White salt marks on your clothing and/or skin once the sweat dries
Sweat that stings your eyes or burns on any cuts or grazes
Sweat that tastes distinctly salty

Interestingly, research involving professional male athletes found an association between how salty athletes believed their sweat was and their measured sweat-sodium concentration.

However, these signs aren't a reliable way to calculate exactly how much sodium you're losing. For that, you'd need information about both your sweat rate and its sodium concentration.¹

Why is your sweat salty in the first place?

Let’s back up a second and explain why your sweat is salty in the first place.

Your sweat glands produce fluid containing water and electrolytes, including sodium. And as that fluid moves towards your skin’s surface, your sweat ducts reabsorb some of the sodium. Some people’s ducts are very good at doing this, so what reaches the surface is dilute. However, some people’s ducts reclaim less, so the sweat still has most of its sodium.

Some people naturally have saltier sweat than others, but your sweat composition isn't completely fixed. Factors like heat acclimatisation, sweat rate and dietary sodium intake can influence how much sodium reaches your skin's surface.

Regular exposure to hot conditions can help your body adapt, including by reducing the concentration of sodium lost through sweat. But, individual differences can remain substantial.

How much salt do you actually lose?

The concentration on its own doesn’t tell you what you’ve lost, for that you need two numbers:

Litres of sweat x mg of sodium per litre = total sodium lost

Let’s look at this in an example:

Two runners go out for an hour together: same pace, temperature, and distance. They both lose 1.2 litres of sweat.

Runner A’s sweat is 400mg/L

1.2 x 400 = 480mg of sodium lost

Runner B’s sweat is 1800mg/L

1.2 x 1800 = 2160mg of sodium lost

That’s four and a half times more, from a run and effort that looked identical.

LIMITED TIME ONLY

$88.00 AUD

$88.00 AUD $140.00 AUD

Free delivery 20% off every order Skip, pause or cancel anytime

Will Goodge is a very salty sweater

Currently, Will Goodge is attempting to run 50 marathons across all 50 US states in just 24 days, covering more than 1,300 miles.

Before the mission Will got his sweat tested.

The result? 1801mg of sodium per litre of sweat.

In other words, he’s a very salty sweater. It’s close to double that of the average which is 991mg/L.²

That test is what kick-started our work with him on a high-sodium formula. Humantra x Rizkia carries 500mg of sodium per serving with no added vitamins, deliberately, so it doesn’t double up on whatever an athlete is already taking.

So, do you need to replace salt after you exercise?

It depends.

On how long you went, how hot it was, how hard you worked, and how salty your sweat was to begin with.

For most everyday workouts, our everyday hydration range is plenty.

But if you’re planning on extraordinary pushes in your training, or you’re building up to one, calculating your hydration strategy can be a key part of this.

The overall thing to remember is that hydration isn’t just set and forget. It changes depending on what you’re doing, where you’re doing it, and for how long.

FAQs

No, it’s completely normal and largely set by genetics. Being at the very salty end doesn’t mean something’s wrong, neither can you train yourself to not lose as much salt. But if something has suddenly changed about your sweating, we’d always recommend a chat to your GP.

No, but it does depend on what you’re doing. Half an hour weight session in the gym? The likelihood is no you won’t need to replace salt. A two hour run in July? Yes, you probably will need to. During longer sessions, and particularly in hot conditions or when sweating heavily, sodium losses may become more relevant. Whether you need additional sodium depends on your individual circumstances and overall food and fluid intake.

But short, ordinary sessions won’t move the needle that much.

For most of us, no. Using the signs described above will be enough to know if you’re a salty sweater or not. But if you’re training for something that will push you further, or if the heat has affected you badly on several occasions, it may be worth doing to understand a hydration strategy that works best for you.

References