For weight loss
Water Intake Calculator for Weight Loss
Quick answer
To support weight loss, drink about 0.5–0.75 oz per pound of body weight (30–40 ml per kg), then add roughly 500 ml (2 cups) before each main meal. That extra water helps with fullness, may slightly raise calorie burn, and supports a modest deficit when paired with food and activity. For a 80 kg (176 lb) adult that means about 3.5–4 litres a day.
Fine-tune
Your daily goal: 3.2 litres, 13 glasses.
Your daily goal
of water a day · about 13 glasses or 6.5 half-litre bottles
- 3.2
- Litres
- 110
- Ounces
- 13
- 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.
Water goal by body weight for weight loss
A quick reference that combines your weight-based baseline with the pre-meal water habit. Use the calculator above for a number tuned to your real activity and climate.
| Body weight | Daily goal | Glasses | Before meals |
|---|---|---|---|
| 60 kg (132 lb) | 3.8 L | 15 | 500 ml × 3 |
| 70 kg (154 lb) | 4.1 L | 16 | 500 ml × 3 |
| 80 kg (176 lb) | 4.4 L | 18 | 500 ml × 3 |
| 90 kg (198 lb) | 4.8 L | 19 | 500 ml × 3 |
| 100 kg (220 lb) | 5.1 L | 20 | 500 ml × 3 |
| 110 kg (243 lb) | 5.4 L | 22 | 500 ml × 3 |
| 120 kg (265 lb) | 5.8 L | 23 | 500 ml × 3 |
How water actually helps weight loss
Water isn't a fat-burning pill, but it supports weight loss in three real ways. First, drinking water before meals increases fullness, which can naturally reduce how much you eat at the meal. Second, drinking water causes a small, temporary rise in resting energy expenditure (your body burns a little energy warming and processing it). Third, sometimes what feels like hunger is actually mild thirst — staying hydrated helps separate the two signals.
The strongest evidence is for the pre-meal habit. A 2010 randomised trial in older adults found that drinking about 500 ml of water before each main meal, alongside a low-calorie diet, led to greater weight loss over 12 weeks than the diet alone. The effect was modest but real, and it costs nothing.
Where water can't help
Drinking more water does not cancel out a poor diet. If your overall calorie intake is well above what you burn, the water you drink won't change the maths. And “drink a gallon a day to lose weight” diets aren't supported by evidence — beyond a point, more water just means more trips to the bathroom, and very large amounts drunk quickly can be dangerous. Hit your goal, spread it out, and pair it with real food and movement.
Frequently asked
How much water should I drink to lose weight?
Aim for the higher end of your weight-based target — about 0.5–0.75 oz per pound (30–40 ml per kg) of body weight, plus an extra 350–500 ml before each main meal. Drinking water before meals can reduce calorie intake modestly, and it temporarily raises the rate at which you burn calories (water-induced thermogenesis). It is a genuine support for weight loss, not a magic fix.
Does drinking water boost your metabolism?
Mildly and briefly. Studies show drinking about 500 ml of water raises resting energy expenditure by around 10–30% for roughly an hour — a real but small effect. Over weeks and months, it can support a modest calorie deficit when paired with diet and activity.
Should I drink a glass of water before every meal?
It's a good habit. A 2010 study in older adults found drinking about 500 ml before each main meal, alongside a low-calorie diet, led to greater weight loss over 12 weeks. Water before meals helps with fullness and may naturally reduce portion sizes.
Does cold water burn more calories than warm water?
A little. Your body warms cold water to body temperature, which uses a small amount of energy. The effect is small — a few extra calories per glass — so temperature matters far less than drinking enough in the first place.
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.