Radiation Dose Equivalent Calculator

About this calculator

Radiation exposure is first measured as absorbed dose, in grays (Gy) — the physical energy deposited per kilogram of tissue — but different types of radiation do different biological damage per gray absorbed. The dose equivalent, in sieverts (Sv), corrects for this by multiplying the absorbed dose by a radiation weighting factor set by the ICRP (International Commission on Radiological Protection): 1 for X-rays, gamma rays and beta particles, but as high as 20 for alpha particles, which cause far more damage per unit of deposited energy.

This conversion is central to radiology, nuclear medicine, and radiation safety programs, where sieverts are used to set occupational exposure limits, report patient doses from CT scans or radiotherapy, and compare risks across radiation sources — from a chest X-ray (a fraction of a millisievert) to occupational limits for radiation workers (tens of millisieverts per year).