Definition
Impression share lost (rank) is the share of impressions you missed due to insufficient ad rank (bid and quality).
How to use it
- Improve rank via relevance, landing page, and creative quality, not only bids.
- Use break-even CPC/CPA constraints to avoid bidding into unprofitable territory.
Why this matters
This term matters because it affects how you interpret performance and make budget decisions. If you use inconsistent definitions or windows, ROAS/CPA can look "better" while profit gets worse.
Practical checklist
- Write a 1-line definition for "Impression Share Lost (Rank)" that your team will use consistently.
- Keep the time window consistent (weekly/monthly/quarterly) when comparing trends.
- Segment results (channel/plan/cohort) before drawing big conclusions from blended averages.
- Sanity-check with a related calculator from the same category on MetricKit.
- Read the related guide (e.g., Max CPC and break-even CPC: how to set bidding targets from margin) for context and common pitfalls.
Where to use this on MetricKit
Calculators
- Paid Ads Funnel Calculator: Model CPM -> CTR -> CVR to estimate CPC, CPA, ROAS, and profit per 1,000 impressions (with margin and variable costs).
- ROI Calculator: Calculate Return on Investment (ROI) for a campaign or project.
- Incrementality Lift Calculator: Estimate incremental conversions, incremental ROAS, and incremental profit from a holdout test.
- Marginal ROAS Calculator: Estimate diminishing returns and find the profit-maximizing ad spend from a simple response curve.
- Target CPA from LTV Calculator: Translate LTV and contribution margin into a target CPA (and break-even CPA) for paid acquisition.
Guides
- Max CPC and break-even CPC: how to set bidding targets from margin: A practical guide to max CPC: translate AOV, CVR, and contribution margin into break-even CPC and a target CPC with buffer.
- Creative + landing page playbook: diagnose CTR/CVR, then set break-even targets: A practical playbook for improving paid ads performance: use CTR/CVR diagnosis, set break-even CTR/CVR/CPM targets from your economics, and fix the biggest lever first.