Definition
Conversion lag is the time delay between an ad interaction and the conversion event (purchase, signup, lead).
Example
If most conversions happen 5-10 days after click, your lag is about a week.
How to use it
- Use lag to choose reporting windows and to avoid turning off campaigns too early.
- Long lag increases the value of cohort reporting and incrementality checks.
- Track lag by channel; lead gen often has longer lag than ecommerce.
- Use p75 lag for budget pacing to avoid undercounting late conversions.
Common mistakes
- Using short attribution windows that ignore lag.
- Pausing campaigns before lagged conversions arrive.
- Assuming lag is stable across seasons or promos.
Measured as
Measure Conversion Lag with a fixed attribution window, conversion event, and spend basis before comparing campaigns or creative tests.
Misused when
- Using short attribution windows that ignore lag.
- Pausing campaigns before lagged conversions arrive.
- Assuming lag is stable across seasons or promos.
Operator takeaway
- Use lag to choose reporting windows and to avoid turning off campaigns too early.
- Long lag increases the value of cohort reporting and incrementality checks.
- Track lag by channel; lead gen often has longer lag than ecommerce.
- Use Conversion Lag only inside a stable attribution rule, conversion definition, and time window so campaign comparisons stay honest.
- If performance changes, check whether the metric moved for a real business reason or because the measurement setup changed underneath you.
Next decision
- Read Attribution vs incrementality: what to trust, when, and how to test if the decision depends on interpretation, policy, or trade-offs beyond the raw formula.
- Decide which report owns Conversion Lag before comparing campaigns, channels, or creative tests.
Where to use this on MetricKit
Guides
- Attribution vs incrementality: what to trust, when, and how to test: A practical guide to attribution vs incrementality: common attribution models, window pitfalls, how MER/marginal ROAS fit in, and how to run holdout/geo tests.