The Heat Dose
What is the heat actually taking?
You already know the summer costs you something. This puts a number on it. Tell it the month, roughly how you spend the day and how much of you there is, and it will estimate the fluid and the sodium that day takes, and what puts the sodium back.
Month in Dubai
Typical daytime high
August in Dubai runs about 42°C in the afternoon at 49% humidity. Brutal. The kind of afternoon most people plan around rather than through.
A day like that costs you
1.1L
Sweat lost
1,030mg
Sodium lost
3.6L
Fluid to aim for
2sachets
SOLT to put it back
One sachet puts back 500 mg of sodium in 750 ml of water, which is where the figures above come from.
At 2 a day that is 60 sachets a month, or 3 boxes a month of 20.
An estimate, not a measurement. Sweat rate and sweat sodium vary a lot between people and from day to day, so treat these as a sense of scale rather than a prescription. Weather figures are long-run Dubai monthly averages, not today’s forecast. If you are managing a medical condition or a sodium-restricted diet, talk to a doctor rather than a website.
How the number is made
Our working, so you can argue with it
None of this is proprietary and none of it is magic. It is four published figures and some multiplication, and we would rather show it than ask you to trust a black box.
- 01
Sweat rate
Starts from a typical rate for the kind of day you picked, then scales up with the heat and with your body size. Sweat tracks surface area more closely than raw weight, so a heavier person sweats more but not proportionally more.
- 02
Humidity
Humid heat costs more than dry heat at the same temperature, because sweat that cannot evaporate does not cool you, so your body simply makes more of it. That is why a Gulf August is harder work than a dry 42°C somewhere else.
- 03
Sodium in that sweat
Sweat carries roughly 600–1400 mg of sodium per litre depending on the person. The "salty sweater" question picks which end of that range to use.
- 04
What replaces it
One SOLT sachet carries 500 mg of sodium. Divide one by the other and you have the sachet count, which we then cap at 3 a day.
Where it stops
The calculator will not suggest more than 3 sachets a day however hard you push the sliders, and it will not tell you to drink more than six litres. Past those points the problem is the day, not the drink, and there is no version of this where we sell you more product to solve it.
Prefer a flavour recommendation to a number? Take the hydration quiz instead, or read The Heat Index for the longer write-ups.
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