Free Tool — Sweat Rate
Find Out How Much You Sweat in a Workout
Weigh yourself before and after exercise, add what you drank, and see your sweat rate per hour. Built for athletes and active adults.
- Free
- No Sign-Up
- Printable
Updated October 24, 2026 · Free to use · Bookmark it
Sweat Rate Calculator
Enter your weight before and after a workout, what you drank and how long you exercised. The tool applies the sweat-rate equation from the NATA fluid replacement position statement. It gives general information for healthy adults and is not medical advice.
Your Results
Enter your numbers and press Calculate. Your sweat loss, sweat rate and weight change appear here.
Follow Your Doctor's Fluid Advice If This Applies to You
People with kidney, heart or other medical conditions, people on diuretics, pregnant people and children follow their doctor's fluid advice, not this tool.
This tool gives no advice on supplements, electrolyte products or sodium.
Athletic Bodies Revamped · Sweat Rate Test Sheet · (408) 561-8431 · athleticmassagetherapist.com
| Date | Conditions | Minutes | Weight Before | Weight After | Fluid | Sweat Rate |
|---|---|---|---|---|---|---|
Educational information only. Sweat rate = (weight before − weight after + fluid drunk − urine) ÷ hours. Source: NATA position statement, J Athl Train 2017. Athletic Bodies Revamped, 220 Thunderbird Dr, Richmond Hill, GA 31324.
How to Run the Test
Run it the same way each time. The numbers only compare if the setup matches.
- Pick one floor scale and use it every time. NATA names a valid, reliable floor scale as the tool for this job.
- Wear the same clothing and gear each time. NATA says to test in the clothing and equipment used for the sport.
- Weigh yourself and write the number down.
- Exercise as usual. Track every drink and the minutes.
- Record any urine passed during the session. The equation subtracts it.
- Weigh yourself again right after, in the same clothing.
- Repeat on hot, mild and cool days and at different effort levels. NATA says to repeat the check several times under realistic conditions.
The equation: sweat loss = weight before − weight after + fluid drunk − urine. Sweat rate = sweat loss ÷ hours. NATA treats 1 kilogram of body weight as 1 liter of fluid.
Worked example from NATA: a recreational runner weighing 80 kg lost 0.8 kg, drank 0.4 L and ran for 0.75 hours. Sweat rate = (0.8 + 0.4) ÷ 0.75 = 1.6 L per hour.
How to Read Your Result
The gauge uses your net weight change, which is weight after minus weight before. Each band comes from the ACSM and NATA documents listed below.
| Band | What the Source Says |
|---|---|
| Within 1% | NATA: plus or minus 1 percent is the euhydrated range. |
| Loss 1–2% | NATA: finish exercise with a loss under 2 percent. Heat regulation is compromised above a 1 percent loss. |
| Loss 2–5% | ACSM: avoid a loss above 2 percent to protect performance. NATA: mild to moderate from an athletic view. |
| Loss Above 5% | NATA: severe from an athletic view, linked to impaired performance, extreme thirst and headache, and hard to replace. |
| Gain | NATA: avoid gaining weight during exercise. Drinking more than you lose is how exercise-associated low blood sodium develops. |
What to Do Next Time
- Drink enough to approximate your sweat loss, and no more. NATA warns against drinking more than you sweat.
- If you do not know your sweat rate, NATA says drinking to thirst most likely prevents overdrinking.
- When the next session starts in under 4 hours, NATA says replacing 100 to 150 percent of the fluid lost is generally needed. With more than 12 hours, food and drinking as desired restore balance.
- Repeat the test in other weather. One result is a starting point.
Urine Color: A Rough Guide Only
Use this strip as a rough guide only. NATA lists urine color as one cue next to thirst and body weight, and says diet, activity and fluid intake change it. Foods, food dyes, vitamins and medications also change the color (Cleveland Clinic). Body weight change is the stronger check.
For a fair look, NATA says to use first-morning urine in a clear container with good light. Color seen in the toilet bowl is not reliable.
If your urine matches the darkest swatch (8) after hard exercise, contact a doctor promptly. NATA ties that color to possible muscle damage and kidney trouble and calls for prompt medical referral.
Drinking Too Much: Warning Signs
Too much fluid is a real risk. NATA calls exercise-associated low blood sodium a potential medical emergency. Early signs of too little and too much fluid overlap: thirst, general malaise, fatigue, headache and vomiting. Only a blood test tells them apart.
NATA lists these signs of low blood sodium:
- Headache that grows severe
- Nausea or vomiting
- Swelling of the hands or feet
- Confusion or disorientation
- Muscle twitching or weakness
- Seizure
Get medical care right away if these appear during or after exercise. Do not guess.
Questions about your own fluid needs go to your doctor or athletic trainer.
Sources and Methodology
- American College of Sports Medicine: Position Stand, Exercise and Fluid Replacement (Sawka et al., Med Sci Sports Exerc 2007) — Source for the 2 percent body weight loss limit during exercise and for estimating sweat rate from weight before and after exercise
- National Athletic Trainers' Association: Position Statement, Fluid Replacement for the Physically Active (McDermott et al., J Athl Train 2017) — Source for the sweat-rate equation, the plus or minus 1 percent, under 2 percent, 2 to 5 percent and over 5 percent bands, the 100 to 150 percent replacement range, the warning against drinking more than you sweat, and the urine color notes
- Cleveland Clinic: Urine Color Chart Interpretation — Source for the note that foods, food dyes, vitamins and medications change urine color
Questions About This Tool
What Is a Normal Sweat Rate?
NATA reports adult sweat rates of 0.5 to 4.0 liters per hour during exercise, so a wide spread is normal. Your own number depends on effort, weather, body size and fitness.
Does This Tool Replace Medical Advice?
No. People with kidney, heart or other medical conditions, people on diuretics, pregnant people and children follow their doctor's fluid advice. NATA notes that children need different rehydration plans than adults.
Why Does the Tool Warn Against Drinking More Than I Sweat?
NATA ties exercise-associated low blood sodium (hyponatremia) to drinking more fluid than the body loses, and calls it a potential medical emergency. The scale shows it: a weight gain across a session means more fluid went in than came out.
How Often Do I Repeat the Test?
NATA says sweat-rate checks are done several times, in realistic conditions and at different effort levels. Try a hot day, a mild day and a cool day, plus a hard session and an easy one, and keep the results side by side.
Is the Urine Color Chart Reliable?
Use it as a rough guide only. NATA lists urine color as one cue next to thirst and body weight, and says diet, activity and fluid intake change it. Foods, vitamins and medications also change the color. Body weight change is the stronger check.
Does the Tool Store My Numbers?
Only if you tick Remember My Numbers. The numbers stay in your own browser on this device. Press Clear Saved Entries to delete them. The tool needs no account and sets no cookies.
Want Hands-On Help With Sports Massage?
Maya Sharpe, LMT, 220 Thunderbird Dr, Richmond Hill, GA. Monday to Friday 9 AM to 8 PM, Saturday 9 AM to 1 PM, Eastern Time.