At 50 kg with moderate activity, you should drink approximately 2.2 liters (about 9 glasses) of water per day. Lighter individuals still need consistent hydration — use the calculator for your exact number.
At 50 kg (110 lbs), your body's baseline water requirement is 1,650 ml per day — calculated at 33 ml per kilogram. This is notably less than what heavier individuals need, and it's important to calibrate accordingly. Forcing yourself to drink "8 large glasses" when you weigh 50 kg may actually be more than your kidneys prefer to process.
Smaller body mass means less total body water — typically 25–30 liters compared to 42+ liters for an 80 kg person. This means a given volume of water loss represents a proportionally larger deficit. Losing just 500 ml at 50 kg is a 1% body weight loss — enough to trigger measurable cognitive effects.
The flip side: lighter individuals also reach overhydration thresholds sooner. The maximum safe hourly intake scales with body size, so at 50 kg, aim to stay under 700 ml per hour.
Even though your baseline is lower, exercise increases needs significantly:
During exercise, a 50 kg person generates less metabolic heat and sweats less than heavier individuals, but the percentage of body water lost can be similar or higher.
Since your total volume is lower, it's easier to meet your target with smaller, consistent sips:
Many smaller-framed people either drink too little because they're not thirsty or drink the same as larger friends and feel uncomfortably full. Neither approach is optimal. Use the calculator above for a number that's calibrated to your exact weight, and adjust based on how your body responds.
Yes — lighter individuals are more susceptible to overhydration. At 50 kg, keep intake under 3 liters unless exercising intensely in heat.