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Convection Calculator

Use Newton's law of cooling to solve convection heat rate, heat-transfer coefficient, area, or temperature difference.

Convection inputs

Result section

warningsolve for heat-rate

Convection heat-transfer rate

2500 W

Secondary results

Heat flux: 250 W/m^2
Heat-flow interpretation: Positive heat transfer follows the stated hot-to-cold or heat-added sign convention.

Unit conversion summary

Unit-normalization summary: SI base units; heat-rate

Warnings

Thermal properties can vary with temperature, pressure, composition, grade, direction, phase, surface condition, manufacturing process, and data source. Verify all values for the actual operating condition.

Assumptions

Calculations are performed locally in your browser and are not submitted to a third-party calculation API.

Calculation steps

Apply convection formula2500 W

Newton's law of cooling

Qdot = h A deltaT

Technical visual

Calculate convection heat transfer from user-entered heat-transfer coefficient, area, and temperature difference.

Engineering interpretation

Positive heat transfer follows the stated hot-to-cold or heat-added sign convention.

What is the convection calculator?

Use this calculator when the convection coefficient is known from measurement, a validated correlation, or a separate design source.

How to use the convection calculator

Select the solve-for target.
Enter the known heat-transfer coefficient, area, heat rate, or temperature difference.
Check the sign of heat flow and verify the source of h.

Input explanations

The coefficient h must be entered; this tool does not run forced- or natural-convection correlations.
Area is the exposed surface area participating in convection.
Temperature difference may be signed to show heat-flow direction.

Notation

Formula notation
Symbol	Meaning	Unit
h	Convection heat-transfer coefficient	W/(m2 K)
A	Convection area	m2
delta T	Surface-to-fluid temperature difference	K

Worked examples

For h = 25 W/(m2 K), A = 10 m2, and delta T = 20 K, Qdot = 5000 W.

Cross-tool workflow

The convection calculator uses q = h A delta T with explicit unit normalization and does not estimate h from Nusselt-number correlations.

Use h in overall U

Common mistakes

Using a heat-transfer coefficient from a different flow regime.
Mixing absolute temperature with temperature difference.
Using projected area instead of wetted or exposed area.

Limitations

Thermal properties are treated as constant user-entered values.
The tool does not select material, fluid, steam, refrigerant, phase-change, or fouling data automatically.
Results are preliminary engineering estimates and do not certify code compliance or safety.
Multidimensional effects, transient storage, contact details, and property variation must be evaluated separately when important.
No Nusselt-number, Reynolds-number, natural-convection, boiling, or condensation correlation is included.

References

Fundamentals of Heat and Mass Transfer: Incropera, DeWitt, Bergman, and Lavine, Fundamentals of Heat and Mass Transfer.
Heat and Mass Transfer: Cengel and Ghajar, Heat and Mass Transfer: Fundamentals and Applications.
Heat Transfer: Holman, Heat Transfer.
Compact Heat Exchangers: Kays and London, Compact Heat Exchangers.
SI units: BIPM, The International System of Units (SI Brochure).
NIST unit guidance: NIST Special Publication 811, Guide for the Use of the International System of Units.

What assumptions does the convection calculator use?

It uses the stated steady or lumped formula with user-entered properties and does not infer hidden losses, standards factors, or temperature-dependent property data.

Are Celsius and Fahrenheit temperature differences handled as offsets?

No. Absolute temperature and temperature difference are separate quantities. Temperature differences use delta units without absolute-temperature offsets.

Can I use the result for final design approval?

No. Use the result for education, estimation, and preliminary review only. Critical work must be checked with standards, validated software, measured properties, and qualified engineering judgment.

Does the calculation run on a remote thermal-property API?

No. Calculations are performed locally in your browser and are not submitted to a third-party calculation API.

Engineering disclaimer

This tool is intended for educational, estimation, and preliminary engineering use. Always verify critical heat-transfer calculations with applicable standards, validated software, measured properties, and qualified professional judgment before using results in real design, manufacturing, construction, safety, or compliance decisions.

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Last reviewed: 2026-06-30

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Convection inputs

Result section

warningsolve for heat-rate

Convection heat-transfer rate

2500 W

Secondary results

Heat flux: 250 W/m^2
Heat-flow interpretation: Positive heat transfer follows the stated hot-to-cold or heat-added sign convention.

Unit conversion summary

Unit-normalization summary: SI base units; heat-rate

Warnings

Thermal properties can vary with temperature, pressure, composition, grade, direction, phase, surface condition, manufacturing process, and data source. Verify all values for the actual operating condition.

Assumptions

Calculations are performed locally in your browser and are not submitted to a third-party calculation API.

Calculation steps

Apply convection formula2500 W

Newton's law of cooling

Qdot = h A deltaT

Symbol

Meaning

Unit

Convection heat-transfer coefficient

W/(m2 K)

Convection area

delta T

Surface-to-fluid temperature difference

Limitations

Thermal properties are treated as constant user-entered values.

The tool does not select material, fluid, steam, refrigerant, phase-change, or fouling data automatically.

Results are preliminary engineering estimates and do not certify code compliance or safety.

Multidimensional effects, transient storage, contact details, and property variation must be evaluated separately when important.

No Nusselt-number, Reynolds-number, natural-convection, boiling, or condensation correlation is included.

References

Fundamentals of Heat and Mass Transfer: Incropera, DeWitt, Bergman, and Lavine, Fundamentals of Heat and Mass Transfer.

Heat and Mass Transfer: Cengel and Ghajar, Heat and Mass Transfer: Fundamentals and Applications.

Heat Transfer: Holman, Heat Transfer.

Compact Heat Exchangers: Kays and London, Compact Heat Exchangers.

SI units: BIPM, The International System of Units (SI Brochure).

NIST unit guidance: NIST Special Publication 811, Guide for the Use of the International System of Units.

Engineering disclaimer

Convection inputs

Calculation mode

Convection inputs

Result section

Secondary results

Unit conversion summary

Warnings

Assumptions

Calculation steps

Newton's law of cooling

Technical visual

Engineering interpretation

What is the convection calculator?

How to use the convection calculator

Input explanations

Notation

Worked examples

Cross-tool workflow

Common mistakes

Limitations

References

Related tools

Print summary

Engineering disclaimer

Need Professional Support?

Convection inputs

Calculation mode

Convection inputs

Result section

Secondary results

Unit conversion summary

Warnings

Assumptions

Calculation steps

Newton's law of cooling

Technical visual

Engineering interpretation

What is the convection calculator?

How to use the convection calculator

Input explanations

Notation

Worked examples

Cross-tool workflow

Common mistakes

Limitations

References

Related tools

Print summary

Engineering disclaimer

Need Professional Support?