Water Intake Calculator
How much water you actually need, based on your bodyweight, how long you train, and the climate you live in. Not eight glasses.
Count real working time, including cardio and walks in the heat.
Fill in the fields above and your number appears here instantly.
What your numbers mean
Your daily target
A baseline set by your bodyweight, plus what training and heat pull out of you. Treat it as a floor on hard days, not a ceiling.
Why hydration shows up in the gym
A two percent drop in body water measurably cuts strength and endurance. Most missed reps blamed on a bad night's sleep are really a dry day.
Electrolytes matter at volume
Once you are drinking well over a gallon, plain water alone can thin out sodium. Salt your food, and add electrolytes on heavy sweat days.
How to adjust after two weeks
- 1Weigh in the same way every morningAfter the bathroom, before food or water, same clothing. One day means nothing. The seven day average is the number you read.
- 2Compare week two's average to week one'sLosing fat: you want a half pound to one percent of bodyweight down per week. Building: a quarter to half pound up. Holding steady inside those ranges means the numbers are right, so leave them alone.
- 3Move calories, not everything at onceOff target for two straight weeks? Change calories by roughly 150 to 200 and hold protein exactly where it is. Protein is what protects the muscle you already built.
- 4Recheck the calculator when your weight moves 10 lbA lighter or heavier body burns a different amount. Ten pounds in either direction is the trigger to run these numbers again.
Numbers are the easy part.
Eating them every day is where people fall off. Turn these macros into a full 7 day meal and training plan, built around your body, free.
Start my free 7 day kickstartCommon questions
How much water should I drink a day?
Start at roughly 0.6 ounces per pound of bodyweight, then add about 14 ounces for every 30 minutes of training and another 10 to 20 percent in real heat. For most lifters that lands between 100 and 160 ounces, which is well above the old eight glasses rule.
Is the eight glasses a day rule real?
It was never based on bodyweight, training, or climate. A 130 pound office worker and a 220 pound lifter training in Florida do not have the same need, which is exactly why this calculator asks for all three.
Does coffee count toward water intake?
Yes. The diuretic effect of normal coffee and tea intake is far smaller than the fluid they deliver, so they count. Alcohol is the exception, since it genuinely pulls fluid out.
How do I know if I am hydrated?
Urine the color of pale straw through most of the day. Dark yellow means catch up. Completely clear all day usually means you are overdoing it and flushing electrolytes with it.
Does drinking more water help fat loss?
Indirectly. Hydration keeps training quality and appetite signals honest, and water before meals blunts intake a little. It does not burn fat on its own, and no amount of it replaces a calorie deficit.