WaterDailyGoal

Myth guide

The 8 Glasses of Water Myth

Quick answer

The “8 glasses of water” rule is not a precise personal target. It is a simple shortcut for about 2 litres a day, which may be enough for some smaller, lightly active adults. Larger bodies, exercise, heat, pregnancy, breastfeeding, and heavy sweating often need more.

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

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Your daily goal: 86 ounces, 10 glasses.

Your daily goal

Updates instantly
86fl oz

of water a day · about 10 glasses or 5 half-litre bottles

Typical range: 75-113 fl oz. Use it as a flexible target, not a medical limit.

Start

1.5 glasses

7:00 AM

Taper

9:00 PM

for better sleep.

Food fluid

+0.6 L

typical food water

2.5
Litres
86
Ounces
10
Glasses
Why this number

We start from a weight-based range, then adjust the point estimate for activity, climate, life stage, and GLP-1 settings. Food water is shown separately so the drink goal stays actionable.

Full methodology

Next step

Your sip schedule

  • 7:00 AM · Start the day1.5 glasses
  • 9:48 AM · Top up1.5 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 down1.5 glasses

Ease off after 9:00 PM for better sleep.

Electrolytes? Skip them today

For everyday hydration, plain water and a normal diet cover your electrolytes just fine.

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

86 fl oz

The link and preview image include your weight and settings.

Maintained by the WaterDailyGoal TeamLast updated

Where the rule helps

Eight glasses is memorable, easy to track, and close to 2 litres if the glass is 250 ml. For some people, that is a decent baseline.

Where it fails

It ignores body size, climate, exercise, food water, caffeine habits, pregnancy, breastfeeding, and medication. A 110 lb office worker and a 220 lb runner should not be handed the same number.

Frequently asked

Is 8 glasses of water a day a myth?

It is a useful shortcut, not a universal rule. Eight 250 ml glasses equals about 2 litres, which may fit some smaller or sedentary adults but undershoots many larger, active, pregnant, breastfeeding, or hot-weather situations.

Does 8 glasses include coffee and tea?

The popular phrase usually means water, but total fluid guidance includes water from beverages and some food. Coffee and tea count toward hydration for most people.

What should I use instead of 8 glasses?

Use body weight as the baseline: about 30–40 ml per kg or 0.5–0.75 oz per pound, then adjust for activity, heat, and life stage.

Sources