What is calculated
WBGT from measured natural wet-bulb, globe, and dry-bulb temperatures.
WBGT Heat Stress Calculator
Use the WBGT Heat Stress Calculator to calculate WBGT from measured environmental sensor temperatures.
Measured-input WBGT
Enter your values, then calculate to see a verified result.
Reference range
How this result is calculated
A clear calculation path based on your inputs.
Inputs usedReview the information used for this result.
Full calculation and sourcesOpen Full calculation and sources to review normalized inputs, the formula sequence, assumptions, and evidence boundaries.
Versioned calculationFormula v1.0.1
Method
Apply the standard weighted sensor equation for sun or no direct sun.
Important boundary
Work-rest actions depend on acclimatization, clothing, workload, policy, and current official guidance.
Measure the right sensorsUse natural wet bulb and black globe.
Not weather-app valuesChoose sun exposureSelect the equation matching the site.
Outdoor direct sunApply local guidanceUse current occupational or sport policy.
Clothing and workload matterInterpretation
C is the measured-input WBGT.
Both environment equations remain visible.
The calculator does not assign a universal safe exposure time.
Use this result
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Report a calculation issue WBGT Heat Stress Calculator: purpose and method
Requires the correct sensor inputs, shows both equations, and avoids an unsupported universal risk band or weather-app approximation.
Keep exploring
Related calculators and resources
Method and test recordFormula v1.0.1
- Recorded scope
- health-activity-performance-completion
- Publisher
- CalculatorGeek
- Reviewed by
- CalculatorGeek Editorial Team
- Recorded review date
- 2026-10-05
- Next source review
- 2027-04-05
- Definition fixtures
- 2 configured scenarios
- Published examples
- 2 shown below
Recorded method
Recompute both weighted equations and verify environment switching, temperature boundaries, and source limitations.
These records describe the published model and reference tests. A test-case count is not a certification of every possible input or an independent specialist review. Editorial policy
Known limitations
- Requires correctly placed and stabilized WBGT sensors.
- Weather-app temperature and relative humidity are not direct substitutes.
- Clothing and workload adjustments are not applied automatically.
- No universal safe/unsafe threshold is assigned.
- Symptoms of heat illness require immediate appropriate action regardless of the calculated value.
Method sources
- OSHA Technical Manual: WBGT and occupational heat exposure
- NIOSH heat stress and WBGT workplace guidance
Latest model update
2026-10-10 - Completed missing semantic entities, relationships, answer targets, query themes, questions, and visible input/output meaning without changing the calculation model.
Reference inputs and expected results
Up to 12 examples from the configured definition fixtures are shown. Expected values use the stated output units; invalid inputs are intended to be rejected.
| Case | Inputs | Expected result |
|---|---|---|
| outdoor sun reference | Environment: outdoor-sun; Natural wet-bulb temperature: 25 C; Black-globe temperature: 35 C; Dry-bulb air temperature: 32 C | Outdoor sun equation: 27.7 C; Indoor or shade equation: 28 C; Measured-input WBGT: 27.7 C (allowed numeric tolerance: 0.0001) |
| indoor shade reference | Environment: indoor-shade; Natural wet-bulb temperature: 24 C; Black-globe temperature: 30 C; Dry-bulb air temperature: 31 C | Indoor or shade equation: 25.8 C; Measured-input WBGT: 25.8 C (allowed numeric tolerance: 0.0001) |
Report an issue with this tool. Include the page URL, units, expected answer, and steps to reproduce. Do not include sensitive personal information.
On this page
What the WBGT Heat Stress Calculator answers
Calculate WBGT from measured natural wet-bulb, black-globe, and dry-bulb temperatures using the correct sun or no-direct-sun equation.
The page refuses a false weather-app shortcut and keeps operational decisions outside the raw index.
How to use the WBGT Heat Stress Calculator
- Measure natural wet-bulb and black-globe temperature at the activity site.
- Measure dry-bulb air temperature for the direct-sun equation.
- Choose whether direct solar load is present.
- Apply the result through the current guidance governing your workplace, team, or event.
Continue with the Sweat Rate Calculator. Measure personal fluid loss in one condition.
Formula, variables and calculation order
outdoor sun WBGT = 0.7Tnwb + 0.2Tg + 0.1Tdb; indoor/shade WBGT = 0.7Tnwb + 0.3Tg.
Inputs are normalized to the displayed base units, the calculation keeps full precision, and rounding is applied only to visible outputs.
Cross-check the next part of the workflow with the Heart Rate Zone Calculator. Keep environmental load separate from heart-rate zones.
Worked example and boundary check
Worked example
With Tnwb 25 C, globe 35 C, and dry bulb 32 C, outdoor-sun WBGT is 27.7 C.
Boundary check
Humidity plus air temperature does not recreate natural wet-bulb and globe measurements under every site condition.
How to interpret the result
WBGT is one environmental input. Acclimatization, metabolic workload, protective clothing, radiant heat, health, hydration, and local policy determine action.
- Requires correctly placed and stabilized WBGT sensors.
- Weather-app temperature and relative humidity are not direct substitutes.
- Clothing and workload adjustments are not applied automatically.
- No universal safe/unsafe threshold is assigned.
- Symptoms of heat illness require immediate appropriate action regardless of the calculated value.
For a separate result with different assumptions, open the Running Race Planner. Adjust a plan manually for course and weather.
Inputs, outputs and result meaning
Requires the correct sensor inputs, shows both equations, and avoids an unsupported universal risk band or weather-app approximation.
Inputs
- Environment
- Choose the equation matching the measurement environment. Available choices are Outdoor with direct solar load and Indoor or outdoor without direct solar load.
- Natural wet-bulb temperature
- Use a measured natural wet-bulb temperature, not ordinary weather humidity. Supported units are degrees Celsius (C).
- Black-globe temperature
- Use a measured black-globe temperature. Supported units are degrees Celsius (C).
- Dry-bulb air temperature
- Used in the direct-sun equation. Supported units are degrees Celsius (C).
Outputs
- Measured-input WBGT
- This is the primary result. It is displayed in C. The display rule uses up to 1 decimal places.
- Outdoor sun equation
- It is displayed in C. The display rule uses up to 1 decimal places.
- Indoor or shade equation
- It is displayed in C. The display rule uses up to 1 decimal places.
- Equation difference for entered sensors
- It is displayed in C. The display rule uses up to 1 decimal places.
Outdoor sun: 0.7Tnwb + 0.2Tg + 0.1Tdb; indoor/shade: 0.7Tnwb + 0.3Tg. Keep the result label, unit, selected mode, and stated limitations together when sharing the answer.
Frequently asked questions
Can I use phone weather data?
Not for this measured-input implementation; it requires natural wet-bulb and black-globe values.
Why are there two equations?
Direct solar load changes the weighting and adds dry-bulb temperature.
What WBGT is safe?
Action limits vary with workload, acclimatization, clothing, policy, and population.
Does WBGT diagnose heat illness?
No. Symptoms require immediate response independent of the index.
Primary sources and evidence limits
- OSHA Technical Manual: WBGT and occupational heat exposure
- NIOSH heat stress and WBGT workplace guidance
Sources were checked 2026-10-05. They establish the stated method or interpretation boundary; they do not make a field estimate equivalent to laboratory measurement, coaching, medical diagnosis, or an individualized safety decision.