Time of Death Calculator

This calculator uses the Glaister equation: Time since death = (98.6°F – Body temperature in °F) / T. The variable T is the cooling rate factor — set to 1.5 when ambient temperature is below 32°F, and 0.75 when ambient temperature is 32°F or above. This is a well-established forensic medicine formula used to estimate postmortem interval.

The Glaister equation is a forensic formula developed to estimate the time elapsed since death based on how much the body has cooled from its normal temperature of 98.6°F. It accounts for ambient temperature because a cold environment causes a body to cool faster than a warm one. The result gives an approximate number of hours since death occurred.

The body loses heat to its surroundings, and the rate of cooling depends on the temperature difference between the body and the environment. In freezing conditions (below 32°F), the body cools more rapidly, so the Glaister equation uses a higher factor (T = 1.5). In warmer conditions, cooling is slower and T = 0.75 is applied.

The Glaister equation provides a rough forensic estimate and is useful as a starting point. Its accuracy can be affected by factors such as clothing on the body, body size and weight, humidity, air movement, cause of death, and fever at time of death. Forensic pathologists use this alongside other indicators like rigor mortis and livor mortis for a more complete assessment.

The formula assumes a normal living body temperature of 98.6°F (37°C). If the deceased had a fever or hypothermia at the time of death, this assumption may introduce error into the estimate. Adjustments are sometimes made in clinical forensic analysis to account for pre-death temperature abnormalities.

Yes. Select Celsius as your temperature unit and the calculator will automatically convert both the body temperature and ambient temperature to Fahrenheit before applying the Glaister equation, then display the results consistently. The formula natively works in Fahrenheit but the conversion is handled for you.

If the body temperature is at or above 98.6°F, the calculated time since death would be zero or negative, which is not a valid forensic result. This may indicate the body has not yet cooled below normal temperature — which can happen in very warm environments, shortly after death, or if the individual had a fever. In such cases, other forensic methods should be used.

This tool is designed for educational and reference purposes. While it accurately applies the Glaister equation, real forensic casework requires a trained forensic pathologist, proper measurement conditions, and consideration of multiple postmortem indicators. Never rely solely on this calculator for legal or investigative conclusions.