Reference scenario: a 59 kg (130 lbs) adult male with moderate activity in a temperate climate — the calculator below is prefilled with exactly these inputs. The calculator returns 2.6 L per day for a male reference input and 2.3 L for a female reference input — about 10 and 9 glasses of 250 ml. At the same weight and climate the full range runs from 2.2 L (sedentary) to 3.1 L (very active). Enter your own weight, sex, activity and climate below to replace these reference inputs with your result.
Weighing 130 pounds puts you at approximately 59 kilograms. Using the clinical baseline of 33 ml per kg, your resting water requirement is about 1.95 liters (65 ounces) per day. Add physical activity and warm weather, and that number climbs to 2.4 liters or more.
At this weight, you're in a range where the classic "8 glasses a day" recommendation (64 oz) is remarkably close to your sedentary baseline — but it falls short if you're active, live in a warm area, or exercise regularly.
For a 130 lb person, here's what hydration looks like throughout the day:
If you work out regularly at 130 lbs, your fluid losses through sweat can be proportionally significant. A moderate 45-minute workout might cause you to lose 16–24 oz of water through perspiration. Intense cardio or hot yoga could push that to 32 oz or more.
The American College of Sports Medicine recommends weighing yourself before and after exercise — every pound lost represents about 16 oz of water you need to replace.
Living in a hot or humid climate at 130 lbs means adding 16–24 oz to your daily baseline. Even air-conditioned environments can be dehydrating, as recirculated air tends to be dry. Winter heating has a similar effect — don't assume cold weather means less water.
About 20% of your daily water intake typically comes from food. Water-rich foods like watermelon (92% water), cucumbers (96%), oranges (87%), and soups can meaningfully contribute to your hydration at 130 lbs. On days when you eat more fruits and vegetables, you may need slightly less plain water.
At this weight, pay attention to urine color (aim for pale straw), energy levels, skin elasticity, and headache frequency. If you're experiencing afternoon energy crashes, increasing water intake by just 16–24 oz spread over the morning hours can make a noticeable difference.
With moderate activity in a temperate climate, the calculator returns 2.6 L per day for a male reference input and 2.3 L for a female reference input. The figure comes from 59 kg × 33 ml, multiplied by the biological-sex factor (×1.0 male, ×0.9 female) and the activity factor, then the climate addition is added and the total is rounded to the nearest 50 ml.
About 10 standard 250 ml glasses for the male reference input and 9 for the female reference input, at moderate activity in a temperate climate. A sedentary day at the same weight is about 9 glasses; very active training is about 12.