An oft-used cliché is that we all have two things in common: death and taxes. In regards to death, humans share an associated reality: the decomposition process. Having noted this, another reality is that the decomposition process is not the same for all bodies. The fact is that there are a variety of factors that affect the decomposition of the human body.

Overview of Human Decomposition

Before diving into a consideration of the factors that affect decomposition, you are first presented with a basic overview of the process itself. Bodily decomposition commences the moment a person dies. At this juncture, what commonly is known as “healthy bacteria” in a person’s intestines and pancreas are deprived of nutrients provided via the bloodstream. When this occurs, the bacteria turn to the organs they inhabit for nutrition. In other words, the bacteria begin to feed on the body itself.

Within a couple of days, the intestines and pancreas are “consumed” by the bacteria. The organs essentially disintegrate. When this occurs, the rest of the body is flooded by the bacteria. The bacteria begin to consume the other organs of the deceased body. Assuming a standard room temperature and moderate humidity (and other factors, as discussed in a moment), it is at this juncture that a body begins to display evidence of decomposition. This is in the form of skin discoloration. 

There are five identified stages of human decomposition, according to biologists. These are:

  • Fresh State
  • Putrefaction State
  • Active Decay
  • Advanced Decay
  • Skeletonization State

Fresh State

The Fresh State of human decomposition is the initial period of two or three days described in the introduction to this section. Whilst there is obvious evidence of death, during the fresh state there is no real outward evidence of decomposition.

Putrefaction State

The Putrefaction State is the one in which decomposition becomes patently obvious and can be fairly described as gruesome to a person who has not been exposed to a body in this state. The body in the putrefaction state begins to bloat significantly because of the build-up of gases within it. During this stage, the accumulation and release of various gases result in an overwhelming stench associated with the body.

Blood vessels undergo a process that technically is known as the formation of sulfhaemoglobin. Initially, this results in the blood vessels appearing to be red then dark streaks over a body. Ultimately, the streaks turn a greenish color.

Bacteria continue to devour the organs of the body, a process which ultimately results in breaches or tears in the skin. When this happens, putrefied fluids flow from the openings. In addition, depending on the location of the remains, insects will be attracted to the body.

Active Decay

Active Decay is the state of black putrefaction. During this stage, most of the mass of the body is lost. In many cases, this is due to the action of insects, including maggots. The abdomen bursts open during this stage. Active Decay lasts for approximately 10 to 25 days, depending on the various factors that are presented in a moment. At the end of this stage, the remnants of the body primarily are bones. The stench associated with the decomposition process continues unabated.

Advanced Decay

During Advanced Decay, what is left of the body (primarily bones) begin to dry out. Because there is little else left, the odors associated the decomposition process begin to abate to the point that there is no real stench. What is left of the body forms a waxy coating that is known as adipocere.

Skeletonization State

The final stage of human decomposition is the Skeletonization State. In this stage, the remains completely dry out. Due to factors that are discussed in a moment, this can occur in a time frame between as little as two weeks up to two years.

Specific Factors Affecting the Decomposition Process

There are 13 key factors that impact the rate of human decomposition. Beginning with the most impactful factor and going to the relatively least significant, these are:

  • Temperature
  • Oxygen availability
  • Embalming
  • Cause of death
  • Burial conditions
  • Access by scavengers
  • Trauma
  • Humidity
  • Rainfall
  • Body size and weight
  • Clothing
  • The surface on which the body rests
  • Foods inside the digestive tract


The most significant factor (by far) affecting the decomposition of a body is ambient temperature, the temperature of the area in which the remains are found. The higher the temperature, the faster the decomposition occurs. This is the reason why funeral homes and other facilities place human remains into coolers. Doing so does not stop the decomposition process altogether; however, it slows the pace of the process significantly.

Oxygen Availability

The availability of oxygen keeps the decomposition process moving forward. This is called aerobic decomposition.

If a body is deprived of oxygen, decomposition will nonetheless occur. For example, if a body is placed in a coffin that is sealed within a concrete burial liner or vault, the oxygen-deprived situation results in anaerobic decomposition. Aerobic decomposition (decay with oxygen) typically is a faster process, depending on other associated factors.


One of the most pervasive misconceptions is that embalming stops the decomposition process. It does not. Rather, embalming slows it down to permit time for viewing and a funeral. Yes, there are famous people who have been embalmed in a manner for perpetual public viewing. However, not only have these bodies been subjected to a specialized embalming process, they are constantly tended to by professionals to stave off decomposition.

Cause of Death

The cause of death can impact the rate of decomposition. For example, a violent death that results in breaks in the skin can result in a faster decomposition process. A person who dies from certain diseases may also leave a body that decomposes at a faster rate.

Burial Conditions

The manner in which a body is buried can also directly impact the rate of decomposition. A body in a traditional metal or hardwood casket, sealed in a concrete vault, will decompose significantly slower than one that is placed in a biodegradable coffin. For example, a green burial is designed in part to facilitate a more rapid decomposition of a body.

Access by Scavengers

Insects and animals can play a significant role in the decomposition process. The process speeds up when insect and animals have access to a body.


A body that has endured trauma before death can decompose more quickly. This occurs because of tears or breaks in the skin and other damage to the surface of the body itself.


Generally speaking, a more humid environment speeds up human decomposition. This particularly is the case during the initial four stages of decomposition set forth previously. However, a more humid environment works to slow the skeletonization process, which moves faster in a hotter, drier situation.


On a related note, rainfall tends to speed up the initial four stages of decomposition, whilst slowing down the final stage or skeletonization.

Body Size and Weight

Fairly recent research on body size and weight was undertaken and reported by the National Institutes of Health. The conclusion of the study suggests that a larger and heavier body decays at a pace that is at least somewhat slower than that of a smaller, lighter one.


Because clothing can protect a body from certain elements that can impact decomposition, it can result in a slowing of the decomposition process in some cases.

The Surface on Which Body Rests

There truly is a myriad of different types of surfaces on which a body might rest. A body placed on organic matter (directly the soil) will decompose faster than one placed within a metal or hardwood casket.

Food in the Digestive Tract

Food in the digestive tract might slightly impact the rate of overall body decomposition. For example, more substantial, protein-rich items like meat can hasten the initial stage of decomposition a bit.

This analysis sums up the primary factors that impact decomposition. These factors do not impact the rate of decomposition in isolation. Rather, they interrelate with one another, resulting in a unique decomposition rate for an individual deceased body.


Emily Kil

Co-Owner of Eco Bear Biohazard Cleaning Company

Together with her husband, Emily Kil is co-owner of Eco Bear, a leading biohazard remediation company in Southern California. An experienced entrepreneur, Emily assisted in founding Eco Bear as a means of combining her business experience with her desire to provide assistance to people facing challenging circumstances. Emily regularly writes about her first-hand experiences providing services like biohazard cleanup, suicide cleanup, crime scene cleanup, unattended death cleanup, and other types of difficult remediations in homes and businesses.