Hydration calculator
GLP-1 Water Intake Calculator
Build a reasonable fluid range for today, with every coefficient traceable to a published source—without turning hydration into a contest.
Estimate today's fluid range
2.6-3.3 liters / day
This is a range because the published planning values are ranges, and it counts all fluids rather than plain water alone. Heat, vomiting, and diarrhea push needs toward or past the top of it without a number anyone can put on them. More is not always better, especially with kidney or heart conditions.
A range, and where every number in it comes from
The baseline is 30 to 35 milliliters per kilogram of body weight, the ordinary adult maintenance-fluid planning range. Exercise adds 0.4 to 0.8 litres per hour, the replacement rate in the American College of Sports Medicine position stand. Nothing else is added, and the result is reported as a range because both published values are ranges.
An earlier version of this page added a flat half-litre for a warm day and a further buffer per half hour of activity. Neither came from a source we could cite, so both are gone. Heat, vomiting, and diarrhea genuinely raise requirements — there is simply no single number that describes by how much, so they belong in your judgment and your clinician's rather than in the arithmetic. Food moisture and other beverages count toward the total.
Water first, electrolytes when useful
Most routine hydration can start with water and regular food. If you are replacing substantial sweat or gastrointestinal losses, compare sodium and sugar—not just flavor—in our electrolyte guide. A 1,000 mg sodium packet is a materially different product from a 55 mg sodium powder.
Use symptoms as a safety signal
Persistent gastrointestinal symptoms are a reason to contact your prescriber. The FDA label specifically connects dehydration from nausea, vomiting, or diarrhea with reports of acute kidney injury. Do not use more fluid or electrolytes to delay appropriate care.
Straight answers
Frequently asked questions
Do GLP-1 medicines cause dehydration?
The medicine itself does not mean everyone needs extra fluid, but nausea, vomiting, diarrhea, reduced intake, and lower thirst can contribute to fluid loss. Current Wegovy labeling warns about kidney injury from volume depletion associated with gastrointestinal reactions.
Do I need an electrolyte powder every day?
Not automatically. Plain water and food are enough for many people. Electrolytes may be useful after meaningful sweat or gastrointestinal losses, but high-sodium products are not a universal daily wellness need. Ask a clinician if you have high blood pressure, kidney disease, heart disease, or take medicines that affect fluid or electrolytes.
Why is the result a range instead of one number?
Because the published planning values are ranges. Adult maintenance fluid is usually planned at 30 to 35 millilitres per kilogram per day, and the American College of Sports Medicine puts replacement during exercise at 0.4 to 0.8 litres per hour. Presenting a single figure would imply a precision that neither source supports.
What about hot weather, vomiting, or diarrhea?
All three raise fluid needs, and none of them has a single agreed number to add. Treat them as reasons to sit at or above the top of the range rather than as arithmetic. Persistent vomiting or diarrhea is a reason to contact your prescriber, not to drink your way through it.
Does coffee count toward fluid intake?
Most nonalcoholic beverages contribute to total fluid intake. Water is still a simple default, and calorie- or sugar-containing drinks should be considered in the context of your full nutrition plan.
When should I contact my prescriber?
Contact your clinician for persistent vomiting or diarrhea, inability to keep liquids down, very low urine output, fainting, confusion, severe weakness, or other concerning symptoms. These are not situations to solve with an online calculator.
Sources and method
Formula choices and health context were checked against the sources below in July 2026. Estimates are rounded so they stay practical.