Sweat Rate and Fluid Replacement
Personal sweat rate and rehydration target from a weigh-in/weigh-out (loss = (pre-post) x 16 + fluid - urine).
Example
You enter
- Pre-activity weight (lb) 180
- Post-activity weight (lb) 177
- Fluid consumed (fl oz) 20
- Duration (hr) 2
You get
- Sweat loss (oz) 68
- Sweat rate (oz/hr) 34
- Body-weight loss 1.667
- Rehydration target 72 oz
Checked against published worked examples from: ACSM / NATA fluid-replacement (weigh-in/weigh-out method).
Details, formula, and sources
ScopeWith the percent body-weight loss flagged against the 2% performance-degradation line. Sets a drinking plan for the next shift.
Formula or tablesweat_loss = (pre - post) x 16 + fluid - urine; sweat_rate = sweat_loss / hours; pct_bw_loss = (pre - post) / pre x 100; rehydration = 1.5 x max(0, deficit).
Source and editionACSM / NATA position on fluid replacement (weigh-in/weigh-out method), by name.
Free accessACSM / NATA position statements are public; individual and medical guidance governs.
What governsGeometry is not forecasting. Avalanche advisory and incident commander govern.
API field namespre_weight_lb, post_weight_lb, fluid_oz, duration_hr, sweat_loss_oz, sweat_rate_oz_hr, pct_bw_loss, rehydration_oz
- Weight-to-volume a pound of body weight lost is about 16 fluid ounces of fluidACSM / NATA