This MDA calculator is provided as reference tool for estimating the MDAs that can be reached for various counting times. There are several MDA equations in use, and many facilities have modified equations to meet their specific requirements. The equation used here is from HASL-300. The results you get from this calculator may differ from those you get with the MDA equation you currently use. The equation is:

T = Sample and Background Count Time

R_{b} = Background Count Rate

E = Counting Efficiency

To use the calculator, enter the sample efficiency as a factor. For example, enter 0.4 if the sample efficiency is 40%. Enter the background count rate in counts per minute (cpm). Enter the count time in minutes. Click the **Calculate MDA** button. The results will be displayed in the MDA field.

Suggested ways to use the calculator:

- Estimate the counting time required for a defined count routine.
- Compare the MDA for two different systems by entering the efficiency (typical vs. typical or warranted vs. warranted) and background values for each individual system of interest.