Published:
How much water do you actually need?
Hydration · 3 min read · April 2026
The widely repeated advice to drink “8 glasses of water a day” has no strong scientific basis. It emerged from a misread of a 1945 US Food and Nutrition Board recommendation that referred to total water from all sources — including food — not pure drinking water. The figure stuck, despite being neither evidence-based nor personalised.
Awra does not use 8 glasses as a fixed target. It calculates your daily water goal from your body weight.
How Awra calculates your water goal
The formula is simple: 35ml of water per kilogram of body weight, converted into glasses of 250ml each.
Daily water goal (glasses) = ROUND( (body weight in kg × 35) ÷ 250 )A few examples:
| Body weight | Daily water (ml) | Daily goal (glasses) |
|---|---|---|
| 60 kg | 2,100 ml | 8 glasses |
| 70 kg | 2,450 ml | 10 glasses |
| 80 kg | 2,800 ml | 11 glasses |
| 90 kg | 3,150 ml | 13 glasses |
Awra sets this goal automatically during onboarding, based on the weight you enter. One glass is 250ml. You log glasses throughout the day; Awra tracks your progress toward your personalised target.
Why 35ml per kilogram?
The 35ml/kg figure comes from standard clinical nutrition guidelines. It reflects the amount of water a typical adult in a temperate environment needs to maintain normal physiological function — supporting kidney filtration, thermoregulation, and circulation — before accounting for significant exercise or extreme heat.
It is an evidence-based starting point, not a magic number. Individual variation exists, but 35ml/kg is a better baseline than a universal fixed number because it scales with body size.
Signs you are consistently under-hydrated
Chronic mild dehydration is common and often not obvious. Thirst is a late signal — you can be meaningfully dehydrated before you feel thirsty.
More reliable indicators:
- Urine consistently darker than pale yellow
- Afternoon fatigue without obvious cause
- Headaches, particularly mid-afternoon
- Difficulty concentrating
If your Awra water log regularly falls short of your goal and you notice any of these signs, the fix is usually straightforward: increase your logged glasses across the day rather than trying to catch up all at once.
Mild dehydration is also one of several cross-dimensional factors in persistent fatigue — alongside sleep consistency and micronutrient intake. For a fuller look at how these patterns interact, see Why Am I Tired All the Time?.
A note on overhydration
For most people in normal conditions, drinking to a reasonable daily target is safe. Overhydration — where excess water dilutes blood sodium to dangerous levels — is rare outside extreme endurance events. It is not a concern at the volumes Awra targets.
Treat your Awra water goal as a floor, not a ceiling. On hot days or after hard exercise, drinking a bit more than your calculated target is fine.
Awra identifies patterns in your logged health data and explains them in plain language. Awra is not a medical device and does not provide medical advice.
For more articles: Health Knowledge Base