Health / Hydration
Water Intake Calculator: Daily Water and Drinks
Compare EFSA and US National Academies total water reference values for adults, pregnancy and breastfeeding. See an estimated drinks share, activity and heat allowances, litres, cups and US fluid ounces.
Water Intake Calculator: Daily Water and Drinks: Shows two population reference values side by side. Drinks are illustrated as 80% of the baseline; the activity allowance of 0.6 L per hour and illustrative heat allowance of 0.5 L per day are added to drinks and total water. Weight is converted for context and does not determine the reference intake. These are estimates rather than personal prescriptions. Runs 100% locally in your browser with zero server file uploads.
- Category
- Health & sport tools
- Runs
- In your browser
- Cost
- Free · no sign-up
- Availability
- Ready to use
Runs entirely in your browser
Adult reference values are starting points, not a personal prescription. Total water includes food and every type of drink.
Weight is shown for context only. These reference values depend on the adult group; this tool does not apply a millilitres-per-kilogram formula.
Weight: 70.0 kg / 154.3 lb
EFSA (2010)
Baseline total water: 2.00 L/day
2.00 L/dayAdjusted planning estimate
| Daily amount | Total water | From drinks |
|---|---|---|
| Litres | 2.00 | 1.60 |
| US cups (240 ml) | 8.3 | 6.7 |
| Metric cups (250 ml) | 8.0 | 6.4 |
| US fl oz | 67.6 | 54.1 |
US National Academies (2004)
Baseline total water: 2.70 L/day
2.70 L/dayAdjusted planning estimate
| Daily amount | Total water | From drinks |
|---|---|---|
| Litres | 2.70 | 2.16 |
| US cups (240 ml) | 11.3 | 9.0 |
| Metric cups (250 ml) | 10.8 | 8.6 |
| US fl oz | 91.3 | 73.0 |
Activity addition: 0.00 L; heat addition: 0.00 L. Both are added to drinks and total water, with food unchanged.
For this illustration, drinks provide 80% of each baseline and food 20%. The US report describes about 80% from drinks; applying the same split to EFSA is a planning assumption, not an EFSA drinks target. Food water varies with diet.
About 6.4 glasses of drinks per day, at 250 ml each
Schedule idea: spread about 267 ml of drinks across each of six breaks while awake, such as breakfast, mid-morning, lunch, mid-afternoon, dinner and early evening. This is an illustration; adjust to thirst and activity, and do not force yourself to finish it. Set a water reminder
Reference intakes
EFSA sets total water at 2.0 L/day for women and 2.5 L/day for men, adding 0.3 L in pregnancy and 0.7 L during breastfeeding. The US National Academies sets 2.7 L for women, 3.7 L for men, 3.0 L in pregnancy and 3.8 L during breastfeeding. These are different population reference values, not minimum amounts everyone must drink. EFSA water opinion (2010) · National Academies water chapter
Activity and heat assumptions
The activity rule of thumb adds 0.6 L per hour. ACSM discusses 0.4–0.8 L/hour for marathon runners; using the midpoint here is a simplified planning allowance, not your measured sweat loss. The hot-climate toggle adds an illustrative 0.5 L/day, not a published reference intake. Needs in heat vary widely; this estimate is unsuitable for prolonged heat exposure or endurance events. ACSM: exercise and fluid replacement (2007)
Practical guides and safety
Thirst and urine colour are practical guides; aim for pale yellow urine. If you have a kidney, heart or liver condition, or a fluid restriction, follow your doctor's advice. Drinking far too much can cause dangerously low blood sodium (hyponatraemia). Avoid forcing large amounts or drinking the daily estimate all at once. NHS: water and hydration · Health New Zealand: low sodium · NHS: fluid restriction guidance
Two total-water reference values
EFSA (2010): women 2.0 L/day, men 2.5 L/day; pregnancy adds 0.3 L and breastfeeding adds 0.7 L. EFSA scientific opinion: https://www.efsa.europa.eu/en/efsajournal/pub/1459. US National Academies (2004): women 2.7 L/day, men 3.7 L/day, pregnancy 3.0 L/day and breastfeeding 3.8 L/day. Water chapter: https://www.nationalacademies.org/read/10925/chapter/6. About 80% comes from drinks in the US data: 2004 announcement: https://www.nationalacademies.org/news/report-sets-dietary-intake-levels-for-water-salt-and-potassium-to-maintain-health-and-reduce-chronic-disease-risk. Applying that share to EFSA is a planning assumption.
Planning allowances and units
Activity adds 0.6 L per hour as a simplified rule of thumb, the midpoint of 0.4–0.8 L/hour discussed for marathon runners in ACSM's 2007 exercise and fluid replacement position stand: https://www.acsm.org/wp-content/uploads/2025/01/Exercise-and-Fluid-Replacement.pdf. It is not measured sweat loss. The heat toggle adds an illustrative 0.5 L/day, not a published reference intake; prolonged heat exposure needs individual advice. The displayed cups use 240 ml (US label) or 250 ml (metric); US fluid ounces use 29.5735295625 ml.
Practical guides and excess water
Use thirst and urine colour as guides, and follow your doctor's advice for fluid restrictions or kidney, heart or liver conditions. NHS water and hydration: https://www.nhs.uk/live-well/eat-well/food-guidelines-and-food-labels/water-drinks-nutrition/ and NHS fluid restriction guidance: https://www.wsh.nhs.uk/CMS-Documents/Patient-leaflets/NutritionandDieteticService/6790-1-Fluid-restriction-guidance.pdf. Drinking far too much can cause hyponatraemia: Health New Zealand low sodium guidance: https://www.healthnz.govt.nz/health-topics/conditions-treatments/blood/low-sodium-hyponatraemia. Spread drinks while awake and adapt to your needs; the example schedule is not a requirement.
How to use it
- Enter your weight for context and choose an adult sex or life-stage group.
- Enter activity minutes and choose whether to include the illustrative hot-climate allowance.
- Compare both reference estimates, then select one for a glasses display and an example schedule.
Privacy & limitations
Calculations run in your browser. This tool does not store or upload your inputs.
Related tools
Frequently asked questions
Why are there two different estimates?
EFSA and the US National Academies used different evidence and populations. Both give adequate intakes for total water, including food and drinks, rather than a minimum amount every individual must drink.
Does the drinks amount mean plain water only?
No. It includes water and other drinks. The displayed 80% share is an illustration based on the US report and is also applied to EFSA for comparison; it is not an EFSA drinks target.
Does my weight change the result?
No. The reference values are grouped by adult sex or life stage. Weight is shown in kg and lb for context; no millilitres-per-kilogram formula is used.
Should I force myself to finish this amount?
No. Thirst and pale yellow urine are practical guides. Follow your doctor's advice for kidney, heart or liver conditions or fluid restrictions. Excessive water intake can cause hyponatraemia, a dangerous reduction in blood sodium.
Free tool · runs in your browser · no account required