Free Water Calculators

Find your daily number

Start here if you want a daily water target.

• Daily Water Intake CalculatorYour daily drinks target from your weight and how much you exercise, with the math shown.
• Water Intake Calculator for Weight LossThe same daily target, plus the before-meal water used in two weight loss trials.
• Pregnancy Water Intake CalculatorThe National Academies figures for pregnancy and breastfeeding, in ounces, liters and bottles.

Training and supplements

For people who sweat a lot or take creatine.

• Sweat Rate CalculatorWeigh yourself before and after a workout, add what you drank, and see liters per hour.
• Creatine Water Intake CalculatorA water number for maintenance or loading, with what the research found.

Bottles and conversions

When you already have a number and want to see it in your own bottle.

• Water Bottles Per Day CalculatorTurn a daily goal into bottles and drink-by times.
• How Many Bottles of Water Are in a Gallon?Convert gallons, liters or ounces into any bottle size.

How these calculators relate

Each of these calculators does one job. The daily intake calculator gives a target from your weight and exercise. The weight loss and creatine versions start from that same target and add what the research on those topics supports. The pregnancy page looks up a published figure, since we found no formula to apply. The sweat rate calculator works from a weigh-in, so it measures what you lost instead of predicting it.

Every page shows its math and its sources. If you want the reasoning before the number, the hydration guides cover what counts, when it's too much, and where common rules like 64 oz came from.

General information for healthy adults, not medical advice. If you are pregnant or breastfeeding, or you have kidney, heart or liver conditions or a fluid limit, ask a clinician first. Terms and medical disclaimer.