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Time of Death

Body cooling, the Henssge method
0Cases
0Within 1 h
Mode
15°20°25°30°35°40°0 h6 h12 h18 h24 hroom 18°
  • Henssge curve
  • 95% range
  • Old rule: 0.83 °C an hour
Core temperature30.0 °C

Estimate

12 h 3 minsince death
9 h 15 min to 14 h 51 min95% range (±2.8 h)
0.62Q, how much of the cooling is left
8 h 26 minthe old 0.83 °C/h rule

The curve starts flat for the first few hours (heat has to reach the skin before the core cools), which is why the old straight-line rule is wrong early on and why cover and weight matter so much.

Set the room, weight and cover; the curve turns the core temperature into hours since death.
More info

How to play

Calculator: set the core temperature, the room temperature, the body weight and what the body was wearing or covered with. The lab draws Henssge's cooling curve and gives the hours since death with the method's 95% range. Simulator runs it the other way: slide the hours since death and watch the core temperature fall. Practice cases give you a scene report: set the bench to match it, then turn the answer into a clock time and check it against the real one. Within an hour counts as close.

The science

Cooling isn't a straight line. For the first few hours after death the core temperature barely moves (the plateau), because heat has to travel out through the body before the core cools. After that it falls roughly exponentially towards the room's temperature, fast at first and slower and slower. The old rule of about 1.5 °F (0.83 °C) an hour ignores both, and the room.

Henssge's nomogram. Claus Henssge fitted a curve to hundreds of measured cases in the 1980s. It works with Q, the share of the starting difference between body and room that is left: Q = (core − room) ÷ (37.2 − room). For rooms up to 23.2 °C, Q = 1.25·e^(Bt) − 0.25·e^(5Bt), where B depends on the body weight. The lab solves that for t, the hours since death. Pathologists use the same formula, often on a printed chart (the nomogram).

Corrective factors. Clothes and covers slow cooling, wind and water speed it up. Henssge's table turns those into a factor that multiplies the body weight: 1 for an unclothed body in still air, 1.1 to 1.4 for layers of clothes, up to 2.4 under a heavy duvet, 0.7 in a draught and 0.5 in still water. Picking the factor is a judgement call, and the range widens when one is used.

Why a range? Real bodies cool differently. Henssge's 95% limits are ±2.8 hours early on, widening to ±4.5 or ±7 hours as the body nears room temperature, where a small error in the reading means many hours. Below Q = 0.2 the method stops being useful.

How accurate is it?

The formula, its constants, the corrective factors and the error ranges are Henssge's published ones. It assumes a steady room temperature, a normal body temperature at death (37.2 °C) and a body lying in one place. Real casework also looks at other signs and adjusts the weight for factors over 1.4 with another table; the lab uses the factor directly. The practice cases add the kind of scatter real bodies show, so a perfect reading isn't always a perfect answer.

Is anything saved? Only how many practice cases you have done and how many were within an hour, on this device.