{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"water-intake"},"result":{"entity_type":"calculator","id":"water-intake","calculator_id":"water-intake","canonical_url":"https://tttkmbb.com/health/water-intake","name":"Water Intake Calculator","title":"Daily Water Intake Calculator – Hydration Needs by Weight and Exercise","category":"health","category_name":"Health","tool_name":"calculate_daily_water_intake","featured_mcp_tool":false,"description":"Estimates daily drinking-water needs from body weight (35 ml per kg) plus an allowance for exercise time, reported in litres, millilitres and 240 ml cups.","use_when":"You want a practical daily fluid target for a healthy adult based on weight and activity.","do_not_use_when":"The person has kidney, heart or liver disease, is pregnant, or works in extreme heat; medical advice supersedes this rule of thumb.","inputs":[{"name":"weight_kg","label":"Weight","type":"number","unit":"kg","required":true,"max":700,"exclusive_min":0,"description":"Body weight in kilograms.","example":70},{"name":"exercise_minutes_per_day","label":"Exercise per day","type":"number","unit":"min","required":false,"default":0,"min":0,"max":600,"description":"Minutes of moderate exercise per day; adds about 355 ml (12 US fl oz) per 30 minutes.","example":30}],"outputs":[{"name":"water_liters_per_day","label":"Water","type":"number","unit":"L/day","decimals":2,"description":"Suggested drinking water per day."},{"name":"water_ml_per_day","label":"Water","type":"number","unit":"ml/day","decimals":0,"description":"Same amount in millilitres."},{"name":"cups_per_day","label":"Cups (240 ml)","type":"number","unit":"cups","decimals":1,"description":"Number of 240 ml (8 US fl oz) cups."}],"input_schema":{"type":"object","properties":{"weight_kg":{"description":"Body weight in kilograms. Unit: kg.","type":"number","maximum":700,"exclusiveMinimum":0,"examples":[70],"x-unit":"kg"},"exercise_minutes_per_day":{"description":"Minutes of moderate exercise per day; adds about 355 ml (12 US fl oz) per 30 minutes. Unit: min.","type":"number","minimum":0,"maximum":600,"default":0,"examples":[30],"x-unit":"min"}},"additionalProperties":false,"required":["weight_kg"]},"output_schema":{"type":"object","properties":{"water_liters_per_day":{"description":"Suggested drinking water per day. Unit: L/day.","type":"number","x-unit":"L/day"},"water_ml_per_day":{"description":"Same amount in millilitres. Unit: ml/day.","type":"number","x-unit":"ml/day"},"cups_per_day":{"description":"Number of 240 ml (8 US fl oz) cups. Unit: cups.","type":"number","x-unit":"cups"}}},"formula":"water_ml = 35 × weight_kg + 355 × (exercise_minutes / 30)","method":"The 30–35 ml/kg rule is a common dietetic heuristic. EFSA's adequate intake for total water (including food) is about 2.5 L/day for men and 2.0 L/day for women; roughly 20–30% of that comes from food.","sources":[{"name":"EFSA (2010) Scientific Opinion on Dietary Reference Values for water","url":"https://www.efsa.europa.eu/en/efsajournal/pub/1459","type":"standard","retrieved_at":"2026-09-23"},{"name":"Mayo Clinic – Water: How much should you drink every day?","url":"https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/water/art-20044256","type":"reference","retrieved_at":"2026-09-23"}],"freshness":{"type":"static","max_age_seconds":null,"note":"Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output."},"examples":[{"name":"70 kg, 30 min exercise","inputs":{"weight_kg":70,"exercise_minutes_per_day":30},"expected":{"water_liters_per_day":2.81,"water_ml_per_day":2805,"cups_per_day":11.7},"url":"https://tttkmbb.com/api/v1/calculate/water-intake?weight_kg=70&exercise_minutes_per_day=30"},{"name":"55 kg, no exercise","inputs":{"weight_kg":55},"expected":{"water_liters_per_day":1.93},"url":"https://tttkmbb.com/api/v1/calculate/water-intake?weight_kg=55"}],"faq":[{"q":"Does coffee or tea count?","a":"Yes, all beverages contribute to total water intake; caffeinated drinks in normal amounts are not net dehydrating."},{"q":"Can I drink too much?","a":"Yes. Drinking many litres in a short time can cause hyponatraemia. Spread intake over the day and drink to thirst during long exercise."}],"tags":["water intake","hydration","fluid needs","how much water"],"related":[{"calculator_id":"tdee","reason":"Estimate calorie needs alongside hydration."}],"links":{"html":"https://tttkmbb.com/health/water-intake","markdown":"https://tttkmbb.com/health/water-intake.md","json":"https://tttkmbb.com/health/water-intake.json","api":"https://tttkmbb.com/api/v1/calculate/water-intake","schema":"https://tttkmbb.com/api/v1/calculators/water-intake","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-23"},"timestamp":"2026-09-23T23:32:17Z"}