Half-life
Half-life in Salesforce refers to the decay-weighted relevance metric used in two distinct features.
Definition
Half-life in Salesforce refers to the decay-weighted relevance metric used in two distinct features. In Salesforce Knowledge and Salesforce Search ranking, half-life is the time interval after which an article''s view-based ranking signal loses half its weight, so newer high-traffic articles outrank older ones over time. In Ideas and Idea Themes, half-life is the period (configured by the admin in days) after which an idea''s up-vote score decays by half, ensuring that recent ideas with strong engagement rank higher than old ideas with long-accumulated votes.
The term is also occasionally used informally to describe the half-life of CRM data: how quickly contact records go stale, how soon a closed-lost opportunity stops being relevant for pipeline analysis, or how long support cases retain reporting value. Those informal uses do not map to a configured setting in Salesforce, but the formal Ideas Half-Life setting under Setup, Ideas Settings, is the one most admins encounter when configuring an Ideas community.
Where Half-life shows up in Salesforce features
Ideas Half-Life setting
Setup, Ideas Settings includes a Half-Life (in days) field. The value determines how quickly an idea''s score decays. Salesforce uses a logarithmic decay function: an idea''s effective score is reduced by half once Half-Life days have passed since the votes were cast. The default is 14 days for most communities, but values from 1 to 365 are supported. Smaller values favor recency; larger values let strong ideas accumulate longer.
How decay drives ranking
The Ideas community sorts the Most Popular and Recent tabs using a score that combines vote count, comment count, and time elapsed. Half-life is the parameter that controls the time component. Two ideas with the same vote count but different ages rank differently: the newer one ranks higher because its score has decayed less. This prevents ancient ideas with high vote counts from monopolizing the top of the list forever.
Knowledge article view-based ranking
Salesforce Knowledge uses a similar decay model for ranking articles in search results when the View Count signal is enabled. Articles viewed recently outrank articles viewed long ago, even when total view counts are equal. The half-life value is not directly configurable in Knowledge, but the underlying ranking algorithm applies a decay similar in spirit to the Ideas setting.
Effect on community engagement
Half-life is one of the most under-appreciated levers in Ideas community design. Setting it too short (1-3 days) makes the front page feel frantic, with no idea staying visible long enough to attract a meaningful audience. Setting it too long (90+ days) lets stale ideas dominate, discouraging new contributors. Most well-tuned communities land between 7 and 30 days.
Decay vs. demotion vs. archival
Half-life affects ranking only; ideas do not disappear or get archived. An idea posted three years ago still appears in search results and on the All Ideas list. The decay only changes how the idea sorts on the Most Popular tab. Demotion (marking an idea as Demote) and archival (moving an idea to a closed status) are separate admin actions that physically remove the idea from active circulation.
Mathematical model
The decay function follows a base-2 exponential: effective_score = raw_score * (0.5 ^ (days_elapsed / half_life)). At elapsed = half_life, the effective score is exactly half the raw score. At elapsed = 2 * half_life, it is a quarter. The function never reaches zero, so even ancient ideas retain a vanishingly small score and remain comparable.
Tuning half-life for a specific community
Start at the default (14 days), monitor the Most Popular tab for one or two weeks, and adjust based on user behavior. If the same five ideas hold the top spots for weeks, shorten half-life. If new ideas vanish from the top before they attract attention, lengthen it. Run small experiments; do not flip from 14 days to 365 days in one move.
Configure Half-Life for an Ideas community
The setting is a single integer field, but the impact on community feel is large. Tune deliberately and monitor results.
- Open Setup, Ideas Settings
Setup, Quick Find, Ideas Settings. The page lists the global Ideas configuration.
- Find the Half-Life field
Scroll to the Ranking section. The Half-Life (in days) field accepts integers from 1 to 365.
- Pick a starting value
Default to 14 days for a new community. Adjust later based on observed engagement.
- Save and monitor
Save the setting. Watch the Most Popular tab over the next 7-14 days. Note how often the top ideas turn over.
- Iterate based on engagement
Shorten half-life if the same ideas dominate for too long. Lengthen if new ideas drop off the front page too quickly. Change in small increments.
- Changing Half-Life takes effect immediately for all ideas. A jump from 14 days to 60 days can dramatically reorder the Most Popular tab the next time the user refreshes.
- The setting affects ranking only, not idea visibility. Stale ideas still appear in search and on the All Ideas list regardless of how short Half-Life is set.
- Communities that demote rarely will see the Most Popular tab dominated by historical ideas regardless of Half-Life. Half-Life is a complement to active moderation, not a replacement for it.
- Salesforce Ideas is on a deprecation glide path. Modern customer-feedback platforms (Salesforce IdeaExchange Reimagined, third-party tools) may not expose a Half-Life setting at all.
Trust & references
Cross-checked against the following references.
- Ideas SettingsSalesforce Help
- Salesforce Ideas OverviewSalesforce Help
Straight from the source - Salesforce's reference material on Half-life.
- Implement IdeasSalesforce Help
About the Author
Dipojjal Chakrabarti is a B2C Solution Architect with 29 Salesforce certifications and over 13 years in the Salesforce ecosystem. He runs salesforcedictionary.com to help admins, developers, architects, and cert/interview candidates sharpen their fundamentals. More about Dipojjal.
Test your knowledge
Q1. What is Half-life in Salesforce scoring contexts?
Q2. What does a short half-life emphasize?
Q3. How should you choose a half-life value?
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