Water Intake Calculator

It starts from a per-kilogram base rate — 33 ml/kg for women, 37 ml/kg for men — then adds on top for activity level and climate, plus a flat 300 ml for pregnancy or 700 ml for breastfeeding if you select them. The base rate itself is scaled so it reproduces EFSA's reference intakes (2.0 L/day for a 60 kg woman, 2.5 L/day for a 70 kg man) rather than just handing everyone the same flat number regardless of size.

Both adjustments scale with your weight rather than adding a fixed amount for everyone. Moving from temperate to hot climate adds roughly 0.5 L/day at a 70 kg body weight, and moderate activity adds about 0.35 L/day at the same weight — a heavier or lighter person gets a proportionally different amount, which is why the jump looks different from what you might see quoted elsewhere.

It's total water — the EFSA quantity this calculator is built on includes water from food as well as drinks, and food typically supplies 20-30% of that total. If you're trying to hit the number purely through drinking, you can reasonably count water-rich foods like fruit, vegetables, and soup toward it rather than treating it as a drinks-only target.

The calculator applies a 1.5 L/day floor regardless of how low your weight, age, or activity inputs would otherwise push the number. This keeps the estimate from suggesting an intake that's unrealistically low for basic hydration, even though the weight-scaled formula alone could technically produce a smaller figure for a very light person.

No — this estimate is for healthy adults and doesn't apply if you have heart failure, kidney disease, or any condition where a clinician has set a specific fluid target or restriction. Follow your provider's guidance instead, since those conditions can make a 'more hydration is fine' assumption actively unsafe.