Enter the yield of the device (in tons, kilotons, or megatons of TNT equivalent) into the calculator to get a very simplified, illustrative EMP “radius” in kilometers or miles.
EMP Radius Formula
The following formula is used by this calculator as a simple scaling relationship (it is not a general, physically validated “EMP radius law”):
R = K * \sqrt(Y)
Variables:
- R is the EMP radius (kilometers)
- K is a scaling constant used by this calculator (set to 1.3 here)
- Y is the yield (kilotons of TNT equivalent, after unit conversion)
In this calculator’s simplified model, multiply K by the square root of the yield Y (in kilotons) to get R (in kilometers).
What is an EMP Radius?
An EMP (electromagnetic pulse) can be produced by a nuclear detonation (especially high-altitude bursts) or certain specialized devices. People sometimes describe effects using an “EMP radius,” but in practice EMP impact is better described by the electric-field strength at a location over time, and what “counts” as disruption depends on the target and the threshold (e.g., kV/m). Because conditions and susceptibility vary widely, there is not one universal EMP radius for a given yield.
How to Calculate EMP Radius?
The following steps outline how this calculator computes the EMP Radius using its simplified scaling relationship:
- First, determine the yield of the device (Y) in kilotons (kt) of TNT equivalent (convert units if needed).
- Next, use the scaling constant (K) used by this calculator, which is assumed to be 1.3 here.
- Next, gather the formula from above = R = K * sqrt(Y).
- Finally, calculate the EMP Radius (R) in kilometers.
- After inserting the variables and calculating the result, check your answer with the calculator above.
Example Problem:
Use the following variables as an example problem to test your knowledge.
Yield of the device (Y) = 50 kilotons
Using the scaling constant (K) = 1.3, this calculator’s model gives: R = 1.3 × √50 ≈ 9.1924 km (≈ 5.7110 miles).
