Time of Death Calculator

This calculator estimates post-mortem interval (PMI) -- the time since death -- from a Newton's-Law-of-cooling model of body temperature decline. Real forensic practice most often cites the Henssge nomogram, a more elaborate double-exponential cooling curve with published correction factors for body weight, clothing, wind, and immersion; this tool implements a simpler single-exponential approximation of the same underlying physics (a body cools toward ambient temperature at a rate proportional to the temperature difference) rather than reproducing Henssge's exact equation. It starts from a normal body temperature of 98.6 deg F and a base cooling rate of about 1.5 deg F/hr for an average adult, then adjusts that rate for body weight (heavier bodies retain heat longer and cool more slowly) and clothing (insulation slows heat loss by roughly 20%, a commonly cited rule-of-thumb rather than a precise published coefficient).

Early in the post-mortem interval, before the body has cooled very far toward ambient, the model treats cooling as roughly linear; once the temperature drop becomes a larger share of the total gap to ambient, it switches to an exponential-decay estimate. Actual forensic PMI estimation also depends on factors this simplified model does not capture -- the body's core-vs-surface temperature gradient, air movement, moisture, and the specific Henssge correction factor -- which is why the confidence range widens from about +/-15% for short intervals to +/-30% for longer ones. Treat any result here as a rough estimate for educational purposes, not a substitute for an actual forensic pathologist's determination.