"Eight glasses a day" is a guess. Your real need depends on your size, how much you sweat, and where you live. Enter a few details to get a daily target in ounces and liters.
Enter a weight between 60 and 500 lb (27 to 227 kg).
Enter between 0 and 300 minutes.
This is a starting point, not a rule. Pale-yellow urine and rarely feeling thirsty are good signs you're close. If your urine is dark or you feel dizzy after workouts, drink more and spread it through the day.
Have heart failure, kidney disease, or a fluid limit from your doctor? Follow their target, not this one.
Daily water needs at a glance
| Body weight | Low activity | 30 min exercise | 60 min exercise |
|---|---|---|---|
| 120 lb (54 kg) | 60 oz (1.8 L) | 72 oz (2.1 L) | 84 oz (2.5 L) |
| 150 lb (68 kg) | 76 oz (2.2 L) | 88 oz (2.6 L) | 100 oz (3.0 L) |
| 180 lb (82 kg) | 91 oz (2.7 L) | 103 oz (3.1 L) | 115 oz (3.4 L) |
| 210 lb (95 kg) | 106 oz (3.1 L) | 118 oz (3.5 L) | 130 oz (3.8 L) |
What your bloodwork says about hydration
Mild dehydration shows up on a standard blood panel. When you're low on fluid:
- BUN and the BUN-to-creatinine ratio rise.
- Sodium and chloride creep up.
- Hematocrit, hemoglobin and albumin read higher because your blood is more concentrated.
- Urine specific gravity goes up and urine darkens.
Insyght measures all of these. If several are high together, your physician may simply ask you to retest well hydrated.
Frequently asked questions
How much water should I drink a day?
Do coffee and tea count?
Can you drink too much water?
Should I drink water before a blood test?
How do I know if I'm dehydrated?
Insyght's panel includes the blood and urine markers that reveal hydration, kidney function and electrolyte balance, reviewed by a physician. $199 a year.
