Physical Intensity Calculator

Calculate the intensity from power and area, with different units. In physics, intensity is power per area, the formula is I=P/A. The unit of intensity calculates as watts per square meter, W/m². Intensity commonly is used for radiant energy. Please insert any two values, to calculate the third one.

Example: a quadratic LED light with an edge length of 17 centimeters has an area of 289 square centimeters (cm²). It has a power of 18 watts. So its intensity is almost 623 watts per square meter. If 2.5 square meters are illuminated with this power, then the intensity is 7.2 watts per square meter. Typical values ​​for lighting rooms are 5 to 50 W/m².

Another example: the sun has a surface area of ​​approximately 6087799000000 square kilometers (km²) and a radiation output of approximately 3840000000000000 gigawatts. This means that its intensity is around 63077 watts per square meter. On average, 1361 watts per square meter reach the earth, averaged over the year; this is the solar constant. This means that the intensity of solar radiation on the earth is significantly higher than that of conventional artificial lighting. This is a freely available and huge amount of light power, which can very cheaply be converted into electrical energy using photovoltaics.

The term intensity is also used in everyday language to mean that something is present in a very strong way. This often refers to limited periods of time or quantities such as surface area or volume. Physical intensity is used in a similar way, except that it refers to concrete quantities, namely power and area. If the radiation power is meant and the radiation is in the visible range, then a luminous area of ​​the same size is brighter the stronger the physical intensity.