Set a daily water target tuned to your body weight, activity level, climate, and life stage. Educational tool — not a medical prescription.
Free tool
Daily target
2,800 mL(2.8 L)
So far today: 1,200 mL (43 % of target)
Still to drink: 1,600 mL (~7 × 250 mL glasses).
Health Canada and the IOM Adequate Intake (AI) for total water (drinks + food) is 3.7 L/day for adult men, 2.7 L/day for adult women — about 80 % comes from drinks. The 30–50 mL/kg baseline above is a more personalised version of that. About 20 % of intake comes from food, which is why the on-screen drink target is below the 3.7 L total figure. Climate, exercise, fever, and breastfeeding all increase needs. Educational tool — listen to your body and your healthcare team if you have kidney, heart, or hyponatremia concerns.
Why “8 glasses a day” isn’t the answer
The 8×8 rule (eight 8-oz glasses, ~2 L) was popularised in the 1940s and never had a rigorous origin. The actual evidence-based number depends on weight, climate, exercise, pregnancy and breastfeeding. A 55 kg sedentary office worker in Vancouver winter needs much less water than an 85 kg labourer in Saskatchewan summer.
Hydrate proactively, not reactively
By the time you feel thirsty, you’re already 1–2 % dehydrated — enough to dull cognitive performance and reaction time. Drink 250–500 mL with each meal and again before bed; carry a refillable bottle and aim to finish it twice during the day. For workouts longer than 60 minutes, switch to a sodium-containing electrolyte drink rather than plain water.
Special situations
Pregnancy adds ~300 mL/day. Breastfeeding adds ~700 mL. Fever, vomiting, or diarrhea sharply increase losses — use an oral rehydration solution rather than water alone. People with kidney disease, congestive heart failure, or SIADH should follow their clinician’s individual fluid plan rather than a generic calculator.
This tool is for educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a licensed Canadian healthcare professional. Read our full disclaimer.