Drink 5–7 mL per kg of body weight 2–4 hours before your run; if urine stays dark, add 3–5 mL/kg about 2 hours before.

Most adults need about 400–800 mL of water per hour of exercise, adjusted for heat, sweat rate, and body size.

Most adults do well by drinking enough to keep urine pale and reaching about 2–2.5 liters of urine a day for kidney health.

Most adults get the best boost with 1.5–3 mg caffeine per kg, taken 30–60 minutes before a workout.

During breastfeeding, aim for about 3.8 liters of total water daily, or drink to thirst with a glass at each feed and meals to stay hydrated.

For caffeine per day, most healthy adults can have up to 400 mg; pregnancy target is 200 mg, and teens should stay under 100 mg.

To prevent kidney stones, drink enough to make 2.5 liters of urine a day—usually 2.5–3 liters of fluids, more in heat or exercise.

Pregnancy hydration target is 8–12 cups (64–96 oz) of fluids daily, or about 2.3 L from beverages within a 3.0 L total water goal.

During most workouts, drink 0.4–0.8 liters per hour and start with ~500 ml two hours before; adjust for heat, pace, and your sweat loss.