The metric ladder
| Layer | Metric | What it helps diagnose |
|---|---|---|
| Exposure | Impressions, reach, frequency | Whether and how often a message was delivered |
| Response | Clicks, CTR, CPC, engagement | Whether the audience responded to the message |
| Conversion | Conversion rate, leads, CPL | Whether the destination and offer created an action |
| Quality | Qualified leads, opportunities, close rate | Whether the action had commercial potential |
| Economics | CAC, LTV, payback, ROAS, contribution | Whether acquisition can support the business model |
Core terms in plain English
Impressions and reach
An impression is one counted delivery of an ad or piece of content. Reach estimates how many distinct people or accounts saw it. Frequency is the average number of deliveries per reached person. These describe exposure, not persuasion or business value.
Click-through rate and cost per click
Click-through rate, or CTR, divides clicks by impressions. Cost per click, or CPC, divides spend by clicks. They can help diagnose message and placement response, but a cheap click is not necessarily a qualified visit.
Conversion rate and cost per lead
Conversion rate divides defined conversions by eligible visits or clicks. Cost per lead, or CPL, divides relevant campaign cost by recorded leads. Both depend on the conversion definition. A newsletter signup and a qualified sales inquiry should not be treated as equivalent.
Customer acquisition cost
CAC divides acquisition cost by new customers. State what costs are included: ad spend only, media plus agency fees, or the broader sales-and-marketing cost. State the period and use a customer count that matches it.
Return on ad spend
ROAS divides attributed revenue by ad spend. A 3.0 ratio means three dollars of attributed revenue for every dollar of advertising spend. That does not mean three dollars of profit. Costs, margins, refunds, sales labor, and attribution uncertainty still matter.
Lifetime value
LTV estimates the value created across a customer relationship. The calculation may use revenue, gross profit, or contribution margin. A useful report states which one, the time horizon, retention assumptions, and whether the figure is historical or modeled.
Payback period and contribution
Payback period estimates how long it takes to recover acquisition cost from customer contribution. Contribution margin is the revenue remaining after variable costs associated with delivering and serving the sale. These measures can make an attractive top-line ROAS look more realistic.
Simple formulas
- CTR = clicks ÷ impressions
- CPC = ad spend ÷ clicks
- Conversion rate = defined conversions ÷ eligible visits or clicks
- CPL = campaign cost ÷ leads
- CAC = acquisition cost ÷ new customers
- ROAS = attributed revenue ÷ ad spend
- LTV:CAC = estimated customer value ÷ customer acquisition cost
These equations are easy. Choosing compatible inputs is the hard part.
Why attribution disagrees
Advertising platforms, analytics tools, CRMs, payment systems, call-tracking tools, and sales teams may credit different sources. They use different identity signals, windows, models, consent states, and timestamps. Privacy controls, browser changes, cross-device behavior, offline decisions, and human referrals create additional gaps.
The goal is not a fictional perfect number. It is a documented reporting model that is consistent enough to support a decision. Compare trends within the same definitions, preserve source data, and label modeled or incomplete figures.
A decision-ready monthly scorecard
- State the business objective and primary conversion.
- Show spend and delivery by channel.
- Show leads, qualified leads, opportunities, and customers with definitions.
- Show cost per stage and known revenue or contribution.
- List tracking gaps, attribution assumptions, and material changes.
- End with three decisions: preserve, stop or repair, and test next.
Four common questions
What is a good CAC?
A good CAC is one the business can support after margin, retention, cash-flow timing, sales capacity, refunds, and delivery costs. A universal benchmark without that context is not useful.
What is a good ROAS?
The required ROAS depends on gross margin, operating costs, repeat purchases, attribution, and the campaign’s role. A lower immediate ROAS may be acceptable for profitable repeat customers; a high reported ROAS may still be unprofitable when margins are thin.
Should every channel have the same target?
No. Branded search, prospecting social, retargeting, and educational content operate at different stages. They need a shared business objective, but their diagnostic thresholds and time horizons can differ.
Which number should a leader watch?
Watch the number closest to the decision you control. For budget allocation, qualified acquisition cost and contribution may matter most. For a page repair, conversion quality and rate may be more actionable. Keep the full ladder available for diagnosis.