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Time Of Death Calculator

Created by Łucja Zaborowska, MD, PhD candidate
Reviewed by Bogna Szyk and Jack Bowater
Based on research by
Madea B. Methods for determining time of death; Forensic Science, Medicine and Pathology; December 2016See 1 more source
Amy E.Rattenbury Forensic Taphonomy - Rigor Mortis; Forensic Ecogenomics; 2018
Last updated: Mar 29, 2024


The time of death calculator is a tool used to assess the time that has passed between a person's death and the discovery of their body.

In forensic science, the time of death is one of the most crucial pieces of information that can be obtained at the crime scene and in the dissecting-room.

⚰️ Read on to discover how to calculate the time of death using two different methods:

  • Calculating time of death using rigor mortis (change in the rigidity of the body); and
  • Calculating time of death using algor mortis (change in the temperature of the body).

How to use the time of death calculator?

  1. To use our time of death calculator, you'll need a set of two temperatures:

    • The ambient temperature - the temperature of the surroundings where the body was found (e.g., the air temperature); and

    • The body temperature - the temperature of the body measured in the rectum.

  2. Your results will be shown in hours by default.

Remember, our calculators work both ways! Feel free to play with the numbers.

Want to explore more? Assess stroke risk factors in patients with atrial fibrillation using the CHA₂DS₂-VASc calculator and evaluate the risk for developing severe cardiovascular complications using the cardiovascular risk assessment calculator.

How to calculate the time of death with body temperature?

How to tell how long a person has been dead? We've got an easy answer for that! Try the following equation:

Time since death = (98.6 − Body temperature) / T

where:

  1. Time since death is given in hours;

  2. Body temperature is given in Fahrenheit (F); and

  3. T is a factor that depends on the ambient temperature:

    • When ambient temperature < 32 °F (0 °C), T = 1.5; and
    • When ambient temperature ≥ 32 °F (0 °C), T = 0.75.

Why does the T factor change?

A body begins to cool from the moment of death — the speed of this process is relatively quicker if the surrounding temperature is low enough to freeze water. We use 32°F (0°C) as the threshold — that's the temperature below which water turns into ice.

Calculating the time of death using algor mortis — answers and key, we've got everything you need. Now, let's try our hand at another method used by professionals. ⤵️

How to determine the time of death using rigor mortis?

Rigor mortis (post-death stiffness) is a method used by forensic doctors and technicians. It is based on the fact that the corpse becomes rigid a few hours after death, and then becomes flexible again after a given period of time.

💡 Rigor mortis can be an important lead in the investigation: if the deceased's hand is still holding the gun, it means that the person didn't shoot themselves - someone else must have placed the firearm, when the rigor mortis was already starting to develop.

Use the table below to estimate the time of death:

Body temperature

Stiffness

Time since death

Warm

Flexible

<2 h

Warm

Stiff

2-8 h

Cold

Stiff

8-36 h

Cold

Flexible

36 h

We can overcome the stiffness of a dead body to bend the limbs. Depending on the time that has passed since death, the stiffness will or will not come back. That is another method that may help us in a precise estimation of the time of death.

🔎 Did you know that overcrowding in an emergency department can increase the mortality rate? Assess ED overcrowding using the NEDOCS calculator.

When is the time of death determined?

The time of death is determined any time the circumstances of the death are unclear. That includes death in a public place with no witnesses, and the deaths of young, healthy people.

The very first assessment is carried out by the police and the forensic scientist at the scene - their main goal is to secure all the evidence. A detailed investigation is then performed during the autopsy.

What are other methods to assess the time of death?
Other methods for calculating the time of death include:

  1. Assessing the interlethal reactions:

    • Pupils' reaction after chemical stimulation;
    • Contractions after hitting the spot above the patella;
    • Muscles' contraction after chemical/electrical stimulation; and
    • Production of sweat after chemical stimulation.
  2. Desiccation (dryness of the body parts, e.g., lips).

  3. Livor mortis - dark discoloration of the skin in parts of the body that were the closest to the ground.

  4. Finally, putrefaction and decomposition of the body.

FAQ

What is rigor mortis?

Rigor mortis is the postmortem stiffening and rigidity of muscles in a deceased body. Since there is no more respiration, the body lacks adenosine triphosphate (ATP) in the muscles. As a result, actin-myosin filament bonds are not broken down by ATP, causing stiffness and muscle contraction.

When does rigor mortis occur?

Rigor mortis occurs around 2 hours after clinical death and begins to disappear around 24 hours after death. The progression of the stiffness typically starts from the facial muscles down to the limbs in the first 6-8 hours of rigor mortis. The stiffness fully disappears after 36 hours after clinical death.

What is algor mortis?

Algor mortis is the change in temperature of a deceased body until it reaches room or ambient temperature. Various factors have an effect on algor mortis, including:

  • Time of death;
  • Clothing;
  • Physical characteristics of the body; and
  • Ambient temperature.

What happens to the body after death?

The body stops its functions and starts to decompose after death. Here are 7 stages of the body after death:

  1. Pallor mortis — paleness of the skin.

  2. Algor mortis — temperature change of the body.

  3. Rigor mortis — stiffness and contraction of muscles.

  4. Livor mortis — dark skin discoloration due to the blood settling.

  5. Putrefaction — first signs of decomposition.

  6. Decomposition — the decay of the body by microorganisms.

  7. Skeletonization — the end of decomposition where all the soft tissue disappears, leaving only the skeleton.

What is the range of death time where resuscitation (CPR) is still possible?

4 to 6 minutes, unless a patient is in hypothermia. The reason behind this is that our brain cells need oxygen in order to function. If the heart stops beating for too long, there will be no blood supply and thus, no oxygen nourishing the brain or others parts of the body.

Patients with cardiac arrest in deep hypothermia can benefit from CPR continued until their core temperature is at least 32 °C.

Łucja Zaborowska, MD, PhD candidate
Body temperature
°F
Ambient temperature
°F
Time since death:
hrs
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