Browse Definitions:


In science, a half-life (also, as a noun, spelled half life ) is the amount of time it takes for half of a substance or entity to undergo some specified process. For example, the half-life of a radioactive substance is the amount of time it takes for half of its atoms to decay, and the half-life of a drug is the amount of time it takes before half of the active elements are either eliminated or broken down by the body. Depending on the particular substance involved, a half-life may be significantly shorter or longer than half of the substance's full period of activity. The concept of a half-life has been adopted by fields outside of science, such as marketing and finance.

In marketing, half-life is a formula for estimating the total responses to be expected from a direct marketing campaign. The half-life of a catalog is the day when half of the consumer responses to the mailing have been received. Sears Canada studied the history of their sales data and found that their catalogs reached their half-life 20 days after being mailed, although the life of the catalog was actually several months. Knowing when a direct marketing campaign reaches the half-life point allows marketers to adapt more quickly to consumer demand.

In finance, the half-life of a mortgage is the date when half of the principal amount has been paid. Because of the way that interest is pro-rated (as a proportion of the total, paid more towards the first part of the life of the mortgage), the mortgage half-life date is generally more distant than the chronological half-way point in the total life of the mortgage.

This was last updated in January 2006

Continue Reading About half-life

Start the conversation

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.


File Extensions and File Formats


  • risk map (risk heat map)

    A risk map, also known as a risk heat map, is a data visualization tool for communicating specific risks an organization faces. A...

  • internal audit (IA)

    An internal audit (IA) is an organizational initiative to monitor and analyze its own business operations in order to determine ...

  • pure risk (absolute risk)

    Pure risk, also called absolute risk, is a category of threat that is beyond human control and has only one possible outcome if ...


  • cloud ecosystem

    A cloud ecosystem is a complex system of interdependent components that all work together to enable cloud services.

  • cloud services

    Cloud services is an umbrella term that may refer to a variety of resources provided over the internet, or to professional ...

  • uncloud (de-cloud)

    The term uncloud describes the action or process of removing applications and data from a cloud computing platform.


  • federated identity management (FIM)

    Federated identity management (FIM) is an arrangement that can be made among multiple enterprises to let subscribers use the same...

  • cross-site scripting (XSS)

    Cross-site scripting (XSS) is a type of injection security attack in which an attacker injects data, such as a malicious script, ...

  • firewall

    In computing, a firewall is software or firmware that enforces a set of rules about what data packets will be allowed to enter or...




  • bad block

    A bad block is an area of storage media that is no longer reliable for storing and retrieving data because it has been physically...

  • all-flash array (AFA)

    An all-flash array (AFA), also known as a solid-state storage disk system, is an external storage array that uses only flash ...

  • volume manager

    A volume manager is software within an operating system (OS) that controls capacity allocation for storage arrays.


  • hybrid hard disk drive (HDD)

    A hybrid hard disk drive is an electromechanical spinning hard disk that contains some amount of NAND Flash memory.