Disclaimer: This calculator provides general health information and estimates for educational purposes only. It is not medical advice, a diagnosis, or a treatment recommendation, and it is not a substitute for care from a licensed healthcare provider. Results are based on population formulas and may not reflect your individual health status, medications, or medical conditions. Never use this tool to start, stop, or adjust any medication, treatment, diet, or exercise program without professional guidance. Any drug-dosing results are teaching aids only and must be independently verified against drug-specific protocols and confirmed by a licensed clinician or pharmacist before use. Always consult a physician, pharmacist, or registered dietitian for guidance specific to your situation.
Example Calculations
160-Minute Moderate Run, 160 lbs
Inputs
Pre-Exercise Weight160 lbs
Post-Exercise Weight158 lbs
Fluid Intake24 oz
Urine Volume4 oz
Duration60 minutes
IntensityModerate
Result
Sweat Rate52.0 oz/hr (1.54 L/hr)
Total Sweat Loss52.0 oz (1.54 L)
Dehydration1.25%
Fluid per 15 min10.4 oz (308 mL)
Sodium per hour1,384 mg
Weight change = (160 – 158) × 16 = 32 oz. Total sweat = 32 + 24 – 4 = 52 oz. Sweat rate = 52 / 1 hr = 52.0 oz/hr = 1.54 L/hr. Dehydration = 2/160 = 1.25%. Recommended intake = 52 × 0.8 / 4 = 10.4 oz per 15 min.
Sweat rate is calculated by weighing yourself before and after exercise, then accounting for fluids consumed and urine produced during the session. The formula is: Sweat Rate = (Pre-Weight – Post-Weight + Fluid Intake – Urine Volume) / Exercise Duration. Weigh yourself nude or in minimal dry clothing for the most accurate results.
Average sweat rate: 24–40 oz/hr (0.7–1.2 L/hr) for moderate exercise
Elite athletes can sweat 60–80+ oz/hr (1.8–2.4+ L/hr)
Sweat rate varies by fitness level, heat acclimatization, and genetics
Test in multiple conditions — your rate changes with temperature and humidity
Intensity
Sweat Rate (oz/hr)
Sweat Rate (L/hr)
Low (walking, yoga)
16–24
0.5–0.7
Moderate (jogging)
24–40
0.7–1.2
High (running, HIIT)
40–56
1.2–1.7
Very High (sprinting)
56–80+
1.7–2.4+
Q
What is a normal sweat rate per hour?
A normal sweat rate ranges from about 0.5 to 2.0 liters per hour (17–68 oz/hr) depending on exercise intensity, temperature, humidity, fitness level, and body size. Most recreational exercisers fall in the 0.7–1.2 L/hr range during moderate activity in temperate conditions.
Light exercise in cool weather: 0.3–0.5 L/hr (10–17 oz/hr)
Heat-acclimatized athletes: up to 2.5–3.0 L/hr in extreme conditions
Individual variation can differ by 2–3x between people doing the same activity
Condition
Typical Range
Fluid Needed/15 min
Cool (60°F)
0.5–0.8 L/hr
3–5 oz
Moderate (75°F)
0.8–1.2 L/hr
5–8 oz
Hot (90°F)
1.2–2.0 L/hr
8–12 oz
Extreme (100°F+)
1.5–3.0 L/hr
10–16 oz
Q
How much dehydration is too much during exercise?
Losing more than 2% of your body weight from sweat during exercise impairs performance and increases heat illness risk. A 160-pound person should not lose more than 3.2 pounds during a session. Beyond 3–4% loss, cognitive function declines and the risk of heat stroke rises significantly.
5%+ loss: dangerous — medical emergency risk, heat stroke possible
Body Weight
2% Loss Limit
3% Loss Limit
130 lbs
2.6 lbs (42 oz)
3.9 lbs (62 oz)
160 lbs
3.2 lbs (51 oz)
4.8 lbs (77 oz)
190 lbs
3.8 lbs (61 oz)
5.7 lbs (91 oz)
220 lbs
4.4 lbs (70 oz)
6.6 lbs (106 oz)
Q
How much sodium do you lose in sweat?
Average sweat sodium concentration ranges from 200 to 1,600 mg per liter, with most people losing 800–1,000 mg/L. A person sweating 1 L/hr typically loses 800–1,000 mg of sodium per hour. Heavy sweaters with salty sweat (white residue on clothing) may lose 1,200–1,600 mg/L.
Average sodium loss: 800–1,000 mg per liter of sweat
Light sweater: 400–600 mg sodium per hour
Moderate sweater: 700–1,200 mg sodium per hour
Heavy/salty sweater: 1,200–2,000+ mg sodium per hour
Sports drinks typically contain 300–500 mg sodium per 16 oz serving
Sweater Type
Sodium (mg/L)
At 1 L/hr Loss
Low sodium
200–500
200–500 mg/hr
Average
500–1,000
500–1,000 mg/hr
Salty sweater
1,000–1,400
1,000–1,400 mg/hr
Very salty
1,400–1,600+
1,400–1,600+ mg/hr
Q
How much fluid should I drink during exercise?
The general guideline is to drink 4–8 ounces every 15–20 minutes during exercise, but the ideal amount depends on your individual sweat rate. Aim to replace about 80% of sweat losses — complete replacement during exercise is not necessary and can cause hyponatremia (overhydration).
Pre-exercise: 16–20 oz, 2–3 hours before; 8 oz, 20–30 min before
During: 4–8 oz every 15–20 min (adjust to your sweat rate)
After: 16–24 oz for every pound lost during exercise
Use electrolyte drinks for sessions longer than 60 minutes
Never drink more than your sweat rate — overhydration is dangerous
This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.
