ALARA: Time, Distance & Shielding
Calculate the radiation dose you receive from a source given dose rate, distance, time and shielding, free online.
About this calculator
The ALARA principle (as low as reasonably achievable) uses three tools: minimise time, maximise distance (inverse square law) and add shielding (each half-value layer halves the rate). Dose = dose rate at the reference distance × (d₀ ÷ d)² × 0.5^(HVLs) × time.