Important Notes: This calculator uses exponential decay principles based on half-life elimination. The formula used is: C(t) = C₀ × (1/2)^(t/t½), where C(t) is concentration at time t, C₀ is initial concentration, and t½ is half-life. Adjustments are made for biological factors (sex, liver function, hydration). Results are estimates only – actual EtG levels vary significantly between individuals. Detection threshold is typically 100-500 ng/mL depending on the test used.