Enter a value and pick its unit (Sievert, Gray, rem, rad, Becquerel, Curie), and the tool converts it to every other radiation unit live.
1 rem = 10 millisieverts (mSv); 1 sievert (Sv) = 100 rem.
Natural background radiation is roughly 2–3 mSv per year for most people, varying by location and altitude.
Gray measures absorbed radiation energy per kilogram; sievert weights that dose by biological harm — for most X-rays and gamma rays, 1 Gy ≈ 1 Sv.