Water Intake by Weight
Your body weight is the single biggest predictor of how much water you need. Look yourself up in the chart, then fine-tune with the calculator below.
Daily Water Intake by Weight Chart
Baseline values use the 35 ml per kilogram guideline (≈ 0.53 fl oz per lb) drawn from EFSA and IOM reference intakes. These are starting points for a temperate-climate rest day — add exercise and heat adjustments below.
| Weight (kg) | Weight (lbs) | Daily Water (ml) | ≈ Bottles (500 ml) |
|---|---|---|---|
| 40 | 88 | 1,400 | 2.8 |
| 45 | 99 | 1,575 | 3.1 |
| 50 | 110 | 1,750 | 3.5 |
| 55 | 121 | 1,925 | 3.9 |
| 60 | 132 | 2,100 | 4.2 |
| 65 | 143 | 2,275 | 4.5 |
| 70 | 154 | 2,450 | 4.9 |
| 75 | 165 | 2,625 | 5.3 |
| 80 | 176 | 2,800 | 5.6 |
| 85 | 187 | 2,975 | 6.0 |
| 90 | 198 | 3,150 | 6.3 |
| 95 | 209 | 3,325 | 6.7 |
| 100 | 220 | 3,500 | 7.0 |
| 105 | 231 | 3,675 | 7.3 |
| 110 | 243 | 3,850 | 7.7 |
| 115 | 254 | 4,025 | 8.1 |
| 120 | 265 | 4,200 | 8.4 |
Fill in your details to see your daily goal
Why Weight Drives Your Water Needs
Two people of different sizes doing identical work lose different amounts of fluid. Larger bodies have greater blood volume, more metabolically active tissue and more skin surface evaporating sweat — every process that consumes water scales with mass. That's why weight-based targets feel noticeably better than generic advice: a 55 kg runner following a 3-liter prescription meant for a 90 kg athlete ends up sloshing, while the 90 kg athlete chasing a 2-liter target quietly runs a deficit by mid-afternoon.
After a significant weight change — more than about 5 kg in either direction — recalculate. Need the full picture with exercise and climate factored in? Use the main water intake calculator.
Frequently Asked Questions
How much water should I drink based on my weight?
A widely used guideline is 35 ml per kilogram of body weight (about 0.53 fl oz per pound). So a 70 kg person starts at about 2.4 liters a day, before adding exercise and climate adjustments. Use the chart or calculator above for your exact number.
How many ounces of water per pound of body weight?
The 35 ml/kg rule converts to roughly half an ounce of fluid per pound — a 150 lb person lands near 75 fl oz, or about 2.2 liters, as their baseline before adjustments for workouts and hot weather.
Do heavier people really need proportionally more water?
Yes. Water volume scales with lean tissue and blood volume, both of which grow with body mass. A 100 kg adult carries more metabolically active tissue than a 55 kg adult and needs meaningfully more fluid to sustain the same balance.
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