BlastSim is a free application for the calculation of the area affected by a nuclear explosion. It is intended for users who wish to know more about the devastating effects of a nuclear explosion and may be useful for evacuation planning. The application makes it easy to calculate the affected area with just a few taps.

The application is intended for use by individual researchers and for educational purposes. It includes lists of weapons in human history and a simulation calculator. 

The app includes an option for inputting a custom yield of the weapon (in kilotons). You can input the yield manually by typing the number and clicking on the 'Set' button. The user can use the calculator to calculate the affected area for the weapons that can be found in human history, such as Little boy, Fat man, and Tsar Bomba.