WaterDailyGoal

The full tool

Water Intake Calculator

Quick answer

WaterDailyGoal uses 33 ml/kg for a beverage planning estimate. The 30–40 ml/kg scenarios and activity/climate coefficients are site assumptions, not validated personal requirements or NAM/EFSA formulas. Pregnancy, breastfeeding, and GLP-1 medicines do not automatically change this estimate. Population total-water references include food; they are not minimum drinking doses. Follow individual clinical advice.

Quick startPick a day type
Used for the base estimate
Activity level
ClimateWhere you spend your day
Fine-tuneMeasure in bottles · Your day
Life stageOptional
Measure in bottlesOptional
Optional — see what's left
glasses
Your dayShapes the sip schedule

Saved profile

Save this setup to resume tomorrow on this browser.

Your daily goal: 2.6 litres, 10.5 glasses.

Your daily goal

Updates instantly
2.6litres

of water a day · about 10.5 glasses · 5 half-litre bottles

Planning scenarios: 2.4-3.1 litres. Use it as a flexible target, not a medical limit.

Start

2 glasses

7:00 AM

Taper

9:00 PM

for better sleep.

Food fluid

+0.7 L

typical food water

2.6
Litres
88
Ounces
10.5
Glasses
Why this number

WaterDailyGoal uses 33 ml/kg for a beverage planning estimate. The 30–40 ml/kg scenarios and activity/climate coefficients are site assumptions, not validated personal requirements or NAM/EFSA formulas. Pregnancy, breastfeeding, and GLP-1 medicines do not automatically change this estimate. Population total-water references include food; they are not minimum drinking doses. Follow individual clinical advice.

Full methodology

Next step

Your sip schedule

  • 7:00 AM · Start the day2 glasses
  • 9:48 AM · Top up2 glasses
  • 12:36 PM · Top up1.5 glasses
  • 3:24 PM · Top up1.5 glasses
  • 6:12 PM · Top up1.5 glasses
  • 9:00 PM · Wind down1.9 glasses

Ease off after 9:00 PM for better sleep.

Electrolytes? Not automatic

Electrolytes are not automatic. Long or heavy sweating and vomiting or diarrhea need different approaches; food, losses and medical restrictions matter. Ask a clinician or pharmacist when illness is involved.

A friendly estimate for healthy adults, not medical advice. Your needs rise with heat, exercise, illness, pregnancy, and some medications. Don't drink more than ~1 litre per hour.

Daily goal

2.6 litres

The link and preview image include your weight and settings.

Maintained by the WaterDailyGoal TeamLast updated Editorial update; not a medical review.

What changes the number?

The calculator is not a dressed-up “8 glasses” rule. These examples use the same formula as the live tool: 33 ml/kg baseline, activity add-ons, climate adjustment, and safety checks.

Example calculator outputs using the live WaterDailyGoal formula
ProfileInputsDaily goalWhat changed
70 kg office daysedentary, moderate2.3 L · 78 oz · 9 glassesWeight baseline only
70 kg moderate daymoderate, moderate2.6 L · 88 oz · 10.5 glasses+0.3 L activity buffer
70 kg active hot dayactive, hot3.2 L · 108 oz · 13 glassesActivity plus 10% heat adjustment
170 lb intense heatintense, hot3.9 L · 132 oz · 15.5 glassesHigh-sweat profile, electrolytes flagged

How much water do you really need?

There is no single magic number. Your body loses water through urine, sweat, breathing, and digestion, and how much you need back depends on your size, how active you are, and the weather where you live. The formula behind this calculator turns those factors into a practical daily target.

Hydration scientists at the U.S. National Academies put adequate total water intake at about 3.7 litres a day for men and 2.7 litres for women — but that figure includes the water in your food. Food contribution varies. Our beverage estimate is a separate planning model; it is not derived by subtracting food from a personal NAM requirement.

Reading your result

  • Litres & ounces — your headline daily goal, the amount to drink across the day.
  • Glasses & bottles— the same goal in everyday containers, so it's easy to track.
  • Electrolytes verdict — context for considering sweat losses, food and clinical restrictions; not an automatic supplement prescription.
  • Pace & stop-time — front-load earlier in the day and ease off before bed to sleep better.

Frequently asked

How does this calculator work?

WaterDailyGoal uses 33 ml/kg for a beverage planning estimate. The 30–40 ml/kg scenarios and activity/climate coefficients are site assumptions, not validated personal requirements or NAM/EFSA formulas. Pregnancy, breastfeeding, and GLP-1 medicines do not automatically change this estimate. Population total-water references include food; they are not minimum drinking doses. Follow individual clinical advice.

Is it exact?

No hydration calculator is exact. Real needs change with heat, illness, altitude, diet, and training. Use this as a grounded starting point.

Should I count coffee and tea?

Yes. Coffee and tea still count toward fluid intake, and food usually adds another meaningful chunk on top.

Sources

  • 1.U.S. National Academies (IOM/NAM), 2005 — Adequate total water intake of about 3.7 L/day for men and 2.7 L/day for women, including water from food and all beverages.Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate, Summary: water adequate intakes; drinks and food
  • 2.European Food Safety Authority (EFSA), 2010 — Adequate total water intake of 2.5 L/day for men and 2.0 L/day for women under temperate conditions.Scientific Opinion on Dietary Reference Values for water, EFSA Journal 8(3):1459, abstract and conclusions
  • 3.Mayo Clinic — General guidance of roughly 2.7–3.7 L of total fluids a day, with thirst and pale-yellow urine as everyday checks.
  • 4.U.S. Geological Survey (USGS) — The human body is about 60% water by weight.