Recommended Intake
Your Personal Hydration Target

NAS & IOM recommended daily water intake with an interactive calculator — personalised by age, sex, and activity level.

Interactive Calculator
Activity-Adjusted Table
Daily Schedule
Hydration Tips

Interactive Hydration Calculator

Select your age group, sex, and typical activity level to see your personalised daily water target from beverages.

Calculate Your Daily Target

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litres per day (from beverages)
Adjust the fields above to calculate

Activity-Adjusted Intake by Age & Sex

Bars scaled to 4.2 L maximum. Columns show Sedentary baseline, Moderate (+0.5 L), and Very Active (+1.2 L) daily totals.

Age Group Sex Sedentary Moderate Very Active
20–30♂ Male 3.0 L 3.5 L 4.2 L
20–30♀ Female 2.3 L 2.8 L 3.5 L
31–45♂ Male 3.0 L 3.5 L 4.2 L
31–45♀ Female 2.3 L 2.8 L 3.5 L
46–60♂ Male 2.8 L 3.3 L 4.0 L
46–60♀ Female 2.1 L 2.6 L 3.3 L
61–75♂ Male 2.5 L 3.0 L 3.7 L
61–75♀ Female 1.9 L 2.4 L 3.1 L
75+♂ Male 2.2 L 2.7 L 3.4 L
75+♀ Female 1.8 L 2.3 L 3.0 L

Sample Daily Hydration Schedule

Spread your intake evenly throughout the day. Avoid large volumes at once — the kidneys can only process ~0.8–1 L per hour.

7:00 AM
400 mL
Wake up — large glass before coffee to rehydrate after sleep
8:30 AM
300 mL
With breakfast — aids digestion and nutrient absorption
10:30 AM
300 mL
Mid-morning — combats focus dip and early dehydration
12:30 PM
350 mL
With lunch — hydration supports afternoon energy levels
3:00 PM
400 mL
Afternoon — beat the 3 PM slump; dehydration mimics fatigue
5:30 PM
400 mL
Pre-exercise — hydrate 30 min before workout; replace during
7:00 PM
300 mL
With dinner — moderate intake; heavy evening fluids disrupt sleep
9:00 PM
200 mL
Evening wind-down — small amount only; avoid large volumes before bed

Daily total shown: ~2,650 mL. Adjust volumes proportionally based on your calculated personal target above.

Practical Hydration Tips

Evidence-based strategies for maintaining optimal hydration throughout the day.

Drink Before You're Thirsty

Thirst is a lagging indicator — by the time you feel thirsty, you may already be 1–2% dehydrated, enough to impair cognitive performance and physical output. Schedule water intake proactively throughout the day rather than reacting to thirst. This is especially important for older adults (60+), who have a diminished thirst response.

Coffee, Tea & Caffeinated Drinks

Moderate coffee and tea consumption (up to 400 mg caffeine/day ≈ 4 cups) does not significantly dehydrate healthy adults — the fluid in the beverage offsets the mild diuretic effect. However, high caffeine intake (energy drinks, espresso shots stacked throughout the day) does reduce net hydration. Count moderate tea and coffee toward your fluid target.

Alcohol & Hydration

Alcohol suppresses antidiuretic hormone (ADH), causing the kidneys to excrete more water than you consume. As a rule of thumb, add 250 mL of water for each standard drink consumed to offset alcohol-induced dehydration. Drink a full glass of water before sleep after drinking to mitigate next-day dehydration symptoms.

Water from Food

Around 20–30% of daily water intake comes from food. High-water-content foods contribute significantly and should be factored into your total fluid intake.

🥒Cucumber96% waterExcellent source
🍉Watermelon92% waterGreat hydrator
🥬Lettuce95% waterLow calorie
🍓Strawberries91% water+ Vitamin C
🍊Oranges87% water+ Electrolytes
🥛Milk87% water+ Protein

The Simple 8×8 Rule

You may have heard "drink 8 glasses of 8 oz (240 mL) per day" — that's ~1.9 L, which is a reasonable minimum for sedentary adult females. However, most people need more. Use the calculator above for a personalised target, and check your urine colour throughout the day as a real-time hydration indicator.