What Is a KPI? How to Set Marketing KPIs, With Formulas and a KPI Tree

What is a KPI? (Short answer)

KPI stands for key performance indicator. It is a measurable value that shows how close a business, team or campaign is to a defined goal.

A number becomes a KPI when three things are true: it is tied to a goal (for example, 'a 1.5% conversion rate by the end of March'), it has an owner (the person accountable for it) and it is measured at a fixed cadence. A number without a target and an owner is just a metric.

Example: monthly sessions on an online store is a metric. If the same company sets the goal 'cut paid cost per order from $35 to $30 in January' and the marketing lead reports it every week, cost per order is that company's KPI.

What is the difference between a KPI and a metric?

A metric is anything you can measure: impressions, clicks, followers, time on page, email open rate. KPIs are the few metrics that most directly drive the business outcome and carry a target. Google Analytics, Meta and Google Ads show you hundreds of metrics; choosing the KPIs is your job.

Test whether a metric is a KPI with three questions:

• Is it tied to the goal? When this number moves, do revenue, profit or customer count move too?
• Does it have an owner? When it gets worse, is there a person or team who will say 'I'll fix that'?
• Does it change decisions? If it drops below target, will budget, campaigns or pages change? If nothing changes, it is decoration, not a KPI.

How do you set KPIs? Build a KPI tree backwards from the goal

The most robust method is to start with the business goal and break it into its multipliers. Every KPI then connects mathematically to the main goal, and 'why are we watching this number?' already has an answer.

An example online store targets $60,000 in monthly revenue. With a $120 average order value (AOV) it needs 60,000 / 120 = 500 orders. With a 1.5% conversion rate it needs 500 / 0.015 ≈ 33,300 sessions.

If 60% of orders are expected from ads, paid's job is 300 orders. At a 40% gross margin, gross profit per order is 120 × 0.40 = $48; that is the most ads can spend per order (break-even CPA). If the company targets $30 per order, the ad budget is 300 × 30 = $9,000 and ROAS is (300 × 120) / 9,000 = 4.0. Break-even ROAS is 1 / 0.40 = 2.5. Paid orders leave 300 × 48 − 9,000 = $5,400 of contribution after ad spend.

The tree gives this KPI set: the main goal is monthly revenue and contribution after ad spend; the supporting KPIs are orders, AOV, conversion rate and cost per order (or ROAS). When one link falls short, it is clear which team fixes what.

• Revenue = Orders × Average order value
• Orders = Sessions × Conversion rate
• Ad budget = Paid orders × Target cost per order
• ROAS = Ad revenue / Ad spend; break-even ROAS = 1 / Gross margin

What are leading and lagging KPIs?

Lagging indicators tell you the outcome, but late: monthly revenue, net profit, churn, customer lifetime value. When the month closes you know what happened, but there is nothing left to do about that month.

Leading indicators show the path to the outcome and warn early: sessions, add-to-cart rate, conversion rate, click-through rate (CTR), cost per lead (CPL), lead-to-sales-call rate. These are tracked weekly or even daily.

A good set contains both. Leadership reads lagging KPIs monthly; the marketing team watches leading KPIs weekly and acts before month end. In the example above, if conversion rate drops to 1.2% in week one, you already know the month will be about 100 orders short.

How do you write a KPI card?

Most KPI arguments happen because the definition was never written down: one person's 'conversion rate' is orders / sessions, another's is orders / users. Write a one-page card for every KPI and announce any definition change before making it.

Example card — Conversion rate. Formula: purchases / sessions × 100. Source: GA4. Owner: ecommerce manager. Cadence: weekly. Baseline: 1.2% (last 90 days). Target: 1.5% by March 31. Thresholds: below 1.0% red, 1.0–1.4% amber. Action: on red, check checkout steps and recent site changes.

• Name and definition: one sentence everyone reads the same way
• Formula: numerator and denominator spelled out (which conversions, which costs)
• Data source: GA4, ad platform, CRM or accounting — pick one
• Owner: one person or team
• Cadence: leading KPIs weekly, lagging KPIs monthly
• Baseline and target: dated and numeric
• Thresholds and actions: red, amber, green and what happens at each

How do you set the target value?

There are two routes and using both is healthiest. Bottom-up: take the last 90-day average as the baseline and add a realistic improvement (conversion rate 1.2% → 1.4%). Top-down: place the business goal in the KPI tree and calculate the value required ($60,000 in revenue needs 1.5%).

The gap between the two numbers tells you whether the plan is realistic. If 1.5% is required and 1.4% looks achievable, you must close the gap through another link: more traffic, a higher AOV or more ad budget. Setting targets as '20% more than last year' skips this check.

Targets should be SMART: specific, measurable, achievable, relevant and time-bound. In practice, every target includes a number and a date.

KPI examples for ecommerce

For an online store, these five KPIs are enough to start. Each has a free calculator on this site.

• Contribution after ad spend = Gross profit − Ad spend (the main goal; use it instead of revenue)
• Conversion rate = Orders / Sessions × 100 (Conversion Rate Calculator)
• Average order value (AOV) = Revenue / Orders
• ROAS = Ad revenue / Ad spend; break-even ROAS = 1 / Gross margin (ROAS Calculator)
• Gross profit margin = (Price − Product cost) / Price × 100 (Gross Profit Margin Calculator); on marketplaces include fees and shipping (Marketplace Profit Calculator)
• Supporting metrics: return rate, repeat purchase rate, shipping cost per order

KPI examples for B2B and service businesses

When a sale starts with a form and closes with a sales team, the ad platform's conversion count is not enough; the KPI chain has to reach the CRM.

• Cost per lead: CPL = Spend / Valid leads
• Lead-to-SQL rate = Sales-qualified leads / Leads × 100
• Win rate = Deals won / Proposals sent × 100
• Customer acquisition cost: CAC = Sales and marketing cost / New customers (CAC Calculator)
• Pipeline value: total value of open opportunities (CRM)

KPI examples for SaaS and subscription businesses

In subscription revenue, growth depends more on existing customers staying and expanding than on new sales. SaaS KPIs therefore focus on the revenue base.

• MRR (monthly recurring revenue) and its growth rate (MRR Calculator)
• Churn rate = Customers lost in period / Customers at start × 100 (Churn Calculator)
• NRR = (Starting MRR + Expansion − Contraction − Churn) / Starting MRR × 100
• LTV:CAC ratio (LTV and CAC calculators)
• CAC payback period = CAC / (Monthly revenue per customer × Gross margin)

Which metrics should not be KPIs?

Numbers that rise easily but do not directly change business results are called vanity metrics. Tracking them is fine; tying targets and bonuses to them makes the team optimise the wrong thing.

• Followers and likes, unless their link to sales is measured
• Impressions and reach, unless read together with cost and outcome
• Sessions alone: more traffic means little if conversion rate is falling
• The platform's own ROAS: platforms can claim the same sale more than once; reconcile revenue with your site or accounting data
• Low CPL: if lead quality is not measured, cheap leads can become expensive customers

What is the difference between a KPI and an OKR?

A KPI is a continuously tracked health indicator: conversion rate is measured every month and expected to stay in a range. An OKR (Objectives and Key Results) is an ambitious change goal for a specific period: 'Lift conversion rate from 1.2% to 1.5% this quarter.'

In practice they complement each other. When a KPI turns red, fixing it can become next period's OKR; when the OKR is hit, the new value becomes the KPI's new normal.

How do you track KPIs in GA4 and ad platforms?

In GA4, mark the events that matter to your business (purchase, form submit, demo request) as key events. By Google's definition, key events are for analysing traffic acquisition and user behaviour, while conversions are what Google Ads uses to measure campaigns and guide bidding. The same sale can be counted differently in each; state on the KPI card which source is the source of truth.

Use consistent UTM parameters on every campaign link so channels are attributed correctly. Otherwise part of your traffic lands in GA4's 'Unassigned' group and channel KPIs break.

Keep all KPIs in one table: KPIs in rows, and target, this week, last week and status (red/amber/green) in columns. In a 15-minute weekly meeting, discuss only red and amber rows.

6 common mistakes when setting KPIs

Once a KPI system is in place, it usually stops working for these reasons:

• Too many KPIs: with 20 indicators nothing is a priority; pick 3–5 per team
• Targets without a baseline: a 1.5% target is a very different job at 0.8% than at 1.4%
• Watching revenue only: revenue growing before margin and ad cost may be growing a loss
• Changing the definition mid-stream: a new denominator breaks the trend; log changes with dates
• Ownerless KPIs: a number everyone owns is a number nobody owns
• Mixing sources: ad platform conversions and CRM customer counts do not belong in the same sum