Forensic science
Postmortem Interval Estimator
This tool applies the Glaister equation to approximate time since death from body temperature, with optional adjustments for clothing and environment. Always corroborate with forensic evidence—temperature alone is imprecise.
Use rectal or core body temperature.
Add up to +100% for heavy clothing/blankets, negative for minimal clothing.
Increase up to 100% if strong airflow accelerates cooling.
Estimated time since death
6.9 hours
Approximate range: 5.4 – 8.4 hours
Intermediate postmortem windowTemperature-based estimates are less precise beyond 12 hours. Combine with rigor mortis, lividity, and insect evidence.
Educational use only. Forensic determinations require comprehensive scene investigation by qualified professionals.
How to Use This Calculator
Measure core body temperature
Obtain a rectal or liver temperature. Document method and time for forensic records.
Record ambient conditions
Note room/outdoor temperature, clothing, coverings, and air movement. These factors affect cooling rate.
Interpret cautiously
Combine temperature-based estimates with rigor mortis, lividity, entomology, witness statements, and investigative context.
Formula
Glaister equation (°F): Hours since death ≈ (98.4 − Tbody) ÷ 1.5
Equivalent (°C): Hours ≈ (37 − Tbody) ÷ 0.83
Temperature-based estimates assume a linear drop during the first 12–18 hours and minimal environmental interference.
Full Description
After death, core temperature decreases toward ambient temperature. The Glaister equation offers a quick field estimate but is limited by clothing, environment, body habitus, and prior illness. Experienced forensic practitioners also evaluate rigor mortis, lividity, ocular changes, gastric contents, and insect activity.
This calculator is intended for teaching and scenario planning. Official determinations require comprehensive forensic examination. Always preserve scene integrity and follow jurisdictional protocols.
Frequently Asked Questions
How accurate is the Glaister equation?
Accuracy decreases beyond 12 hours and with non-standard conditions. Expect variance of ±1–2 hours or more.
What if the body was in water?
Water accelerates cooling. Specialized forensic models are needed; do not rely on this calculator.
Does fever before death affect results?
Yes. Elevated premortem temperature alters the baseline; adjust interpretation accordingly.
When should entomology be used?
For advanced decomposition or outdoor scenes, insect development stages provide more reliable estimates than temperature.