Popular conversions
1 pairsWatt per Square Meter ↔ Kilowatt per Square Meter
W/m² ↔ kW/m²
Unit guides
2 unitsDetailed guide to this category
Heat flux measures the rate of heat energy transfer through a given surface area.
Watt per square meter is the SI derived unit, used in building heat loss and solar radiation calculations.
- Physical quantity
- Heat flux
- SI unit
- Watt per square meter
- Typical use
- Surface heat transfer and solar radiation
What is heat flux?
Heat flux is the rate of heat energy transferred through a unit surface area.
It is used for building heat loss calculations and solar panel radiation analysis.
Heat flux and total heat transfer
Heat flux is a density of heat-transfer rate over area, not the total heat-transfer rate. Multiplying heat flux by the relevant area gives a total power value when the flux is uniform.
This distinction matters when comparing a small component with a large wall or roof: the same flux over a larger area produces a larger total heat transfer.
Using heat-flux units
Watts per square meter is the standard SI-form unit. Kilowatts per square meter is useful when the value is large, such as high-intensity thermal or solar applications.
Specify whether a value represents incoming, outgoing or net heat flux, and keep surface area and boundary conditions consistent when comparing results.
Unit comparison table
| Unit | Symbol | SI equivalent | System | Common use |
|---|---|---|---|---|
| Watt per Square Meter | W/m² | SI reference unit | SI | Building physics and surface heat transfer |
| Kilowatt per Square Meter | kW/m² | 1 kW/m² = 1,000 W/m² | SI prefix | High-intensity thermal and solar analysis |
Units
| Unit | Symbol | Information |
|---|---|---|
| Watt per Square Meter | W/m² | View unit guide |
| Kilowatt per Square Meter | kW/m² | View unit guide |