By CalculatorInn Team · Updated: 2026-03-22 · Free & accurate · Instant results
Determine your recommended daily water intake based on body weight, physical activity, and environmental factors.
Interactive Water Intake Calculator
JavaScript is required for the interactive calculator. Enable JavaScript to use this tool.
Base = Body Weight (lbs) × 0.5 oz; adjusted for activity and climate
A common guideline is half your body weight in ounces as a baseline, with additional hydration for exercise (12-36 oz extra) and hot climates (16-32 oz extra).
The '8 glasses' rule (64 oz) is a rough approximation. Actual needs depend on body weight, activity, and climate. A 200-lb active person needs significantly more than 64 oz.
Partially. While caffeine is a mild diuretic, coffee and tea are mostly water and do contribute to hydration. However, pure water is still recommended as the primary source.
Fast, accurate calculators for finance, work, tech, and everyday math. Clear formulas and instant answers.
Browse 600+ free online calculators for finance, math, health, tech, business, education, salary, time, and unit conversions. Instant, accurate results with formulas and worked examples.