Enter the full width at maximum and the photo peak into the calculator to determine the energy resolution.

Energy Resolution Formula

The following formula is used to calculate an energy resolution.

ER = FWHM * 100 / PP
  • Where ER is the energy resolution (%)
  • FWHM is the full width half maximum
  • PP is the photo peak

To calculate the energy resolution, multiply the full width half maximum value by 100, then divide by the photo peak.

What is Energy Resolution?


Energy resolution is a measure of the percent of energy of incoming photons on an imaging device.

How to calculate Energy Resolution?

Example Problem:

The following example outlines how to calculate an energy resolution.

First, determine the FWHM of a specific energy. in this example, the FWH is found to be 8%.

Next, determine the photo peak. For this example, the photo peak is 140KeV.

Finally, calculate the energy resolution using the formula above:

%ER = FWHM * 100 / PP

%ER = 8 * 100 / 140

%ER = 5.714%