Formula guide
Water Intake Per kg of Body Weight
Quick answer
A practical metric rule is 30–40 ml per kg of body weight per day. For a 70 kg adult, that is about 2.1–2.8 litres. Use the lower end for cool, sedentary days and add more for training, hot weather, pregnancy, breastfeeding, illness, or heavy sweating.
Fine-tune
Your daily goal: 2.6 litres, 10.5 glasses.
Your daily goal
of water a day · about 10.5 glasses or 5 half-litre bottles
- 2.6
- Litres
- 88
- Ounces
- 10.5
- Glasses
Your sip schedule
- 7:00 AM · Start the day2 glasses
- 9:48 AM · Top up2 glasses
- 12:36 PM · Top up2 glasses
- 3:24 PM · Top up2 glasses
- 6:12 PM · Top up2 glasses
- 9:00 PM · Wind down2 glasses
Ease off after 9:00 PM for better sleep.
Electrolytes? Skip them today
For everyday hydration, plain water and a normal diet cover your electrolytes just fine.
A friendly estimate for healthy adults, not medical advice. Your needs rise with heat, exercise, illness, pregnancy, and some medications. Don't drink more than ~1 litre per hour.
Per-kg water chart
| Body weight | Low end | High end | Glasses |
|---|---|---|---|
| 50 kg | 1.5 L | 2.0 L | 8 |
| 60 kg | 1.8 L | 2.4 L | 10 |
| 70 kg | 2.1 L | 2.8 L | 11 |
| 80 kg | 2.4 L | 3.2 L | 13 |
| 90 kg | 2.7 L | 3.6 L | 14 |
| 100 kg | 3.0 L | 4.0 L | 16 |
Why this site starts near 33 ml/kg
The calculator uses about 33 ml/kg as a steady middle baseline, then adds activity, climate, and life-stage adjustments. That keeps the default realistic without pretending body weight is the only variable.
Frequently asked
How much water per kg of body weight should I drink?
A practical metric range is 30–40 ml per kg of body weight per day. For a 70 kg adult, that is about 2.1–2.8 litres before activity, heat, pregnancy, breastfeeding, or heavy sweat adjustments.
Is 35 ml per kg a good formula?
Yes, 35 ml/kg is a useful middle estimate for many healthy adults. This site uses about 33 ml/kg as the baseline, then adds activity and climate adjustments.
Should athletes use more than 40 ml per kg?
Often yes on training days. Athletes should add session fluid based on sweat rate instead of relying only on a per-kg daily rule.
Sources
- 1.U.S. National Academies (IOM/NAM), 2005 — Adequate total water intake of about 3.7 L/day for men and 2.7 L/day for women, including water from food and all beverages.
- 2.European Food Safety Authority (EFSA), 2010 — Adequate total water intake of 2.5 L/day for men and 2.0 L/day for women under temperate conditions.
- 3.Mayo Clinic — General guidance of roughly 2.7–3.7 L of total fluids a day, with thirst and pale-yellow urine as everyday checks.