Water Intake & Sleep Cycle Calculator
Get your daily hydration target and optimal bedtimes based on 90-minute sleep cycles.
Water & sleep times appear here
Enter your details and click Calculate.
Daily Water Intake Formula
Water (L) = Weight (kg) × 0.033 + Activity Bonus
Activity bonuses: Sedentary +0L | Light +0.35L | Moderate +0.5L | Active +0.75L | Very Active +1.0L
Sleep Cycle Formula
Bedtime = Wake Time − (Cycles × 90 min) − 15 min
The 15-minute buffer accounts for average sleep onset latency. Complete 5 cycles (7.5h) for optimal recovery.
Frequently Asked Questions
Does coffee count toward daily water intake?
Moderate coffee consumption (1–3 cups/day) has minimal diuretic effect and can count toward hydration. Alcohol, however, is dehydrating and should not be counted.
Is 7–8 hours always enough sleep?
Sleep quality matters as much as quantity. Waking mid-cycle leaves you groggy. 7.5 hours (5 cycles) or 6 hours (4 cycles) aligned with your wake time is often better than 7.5 hours at a random time.
What happens if I drink too much water?
Overhydration (hyponatremia) is rare but possible with extreme intake. Do not exceed 3–4 L above this calculator's recommendation without medical advice.
Last reviewed: October 2024
Sources:
EFSA dietary reference values for water· NHS — How much water should I drink?· CDC — How much sleep do I need?
Hydration and sleep needs vary by individual health, climate, and activity. Consult a healthcare professional.