Marketing KPI Calculator — CTR, CPC, CPM, CPA, CAC & ROAS
Enter the numbers you already have and get every marketing metric they can produce, with the formula shown next to each result.
Most marketing metrics come from dividing one number you already have by another. This marketing KPI calculator takes traffic, ad spend, impressions, clicks, conversions, leads, customers and revenue for a single period and derives all twelve metrics those figures support — CTR, CPC, CPM, conversion rate, CPA, CAC, ROAS, AOV, LTV, LTV:CAC, lead-to-customer rate and pages per session.
You don't choose a metric first. Fill in whatever you have, and anything that can be calculated appears immediately; anything that can't is listed with the exact input it's waiting for. It's built for in-house marketers pulling a monthly report together, freelancers checking a client account, and anyone who wants the arithmetic and the formula in one place instead of a spreadsheet nobody remembers building.
Your numbers
Your metrics appear here
Enter any two related numbers — like clicks and impressions — and the matching KPIs are calculated instantly. The more you fill in, the more metrics unlock.
Need more than a free tool? Ask Kestry Chat Agent about your campaign strategy, marketing questions and customer workflows.
How this marketing metrics calculator works
The calculator holds one set of period figures and runs every formula against them as you type. Each result carries its formula underneath, so a number you can't explain in a meeting is never far from its derivation. Twelve metrics are covered:
- Advertising efficiency — CTR, CPC, CPM
- Conversion and acquisition cost — conversion rate, CPA, CAC, lead-to-customer rate
- Value and return — ROAS, AOV, LTV, LTV:CAC
- Engagement — pages per session
The currency selector changes formatting only; it doesn't convert anything. Every calculation runs in your browser, so account-level spend and revenue figures never leave the device.
Which numbers give you which metrics
Every metric has a dependency list. When one of its inputs is blank, the metric moves to the "needs more data" list and names the missing figure rather than showing a misleading zero. This table is the whole dependency map — useful before you go pulling data, so you know which two or three fields actually matter.
| Numbers you enter | Metrics you get |
|---|---|
| Impressions + clicks | CTR |
| Ad spend + clicks | CPC |
| Ad spend + impressions | CPM |
| Visitors + conversions (or leads) | Conversion rate |
| Ad spend + conversions (or leads) | CPA (cost per lead if you enter leads only) |
| Ad spend + new customers | CAC |
| Revenue + ad spend | ROAS |
| Revenue + new customers | AOV |
| Revenue + customers + purchase frequency | LTV (simple) |
| The four above plus ad spend | LTV:CAC |
| Leads + new customers | Lead-to-customer rate |
| Page views + sessions | Pages per session |
A metric also reports missing data when its denominator is zero. Zero clicks means there is no cost per click to report, not a CPC of nothing.
Advertising efficiency: CTR, CPC and CPM
These three describe what happens between money leaving your account and a person arriving on your site. The worked figures below all come from one campaign month: 250,000 impressions, 6,000 clicks, 5,000 in ad spend, 12,000 visitors, 300 conversions from 200 leads, 80 new customers and 20,000 in revenue.
CTR (click-through rate)
CTR = Clicks ÷ Impressions × 100 6,000 ÷ 250,000 × 100 = 2.4%
CTR is the cleanest read you have on creative and targeting, because it's the only metric here untouched by your landing page or your pricing. A CTR falling week over week on a campaign you haven't changed usually means frequency is climbing and the audience is tiring of the creative. It isn't comparable across placements — search ads answering an explicit query behave nothing like a display banner interrupting an article.
CPC (cost per click)
CPC = Ad Spend ÷ Clicks 5,000 ÷ 6,000 = 0.83
CPC is what one visit from advertising costs. It's set by auction competition and by how relevant the platform judges your ad to be, so it's only partly under your control — a competitor raising budgets in your category moves your CPC without you touching anything.
CPM (cost per thousand impressions)
CPM = Ad Spend ÷ Impressions × 1,000 5,000 ÷ 250,000 × 1,000 = 20.00
CPM prices reach rather than response, which makes it the buying unit for awareness work and the number to watch when you're being outbid. Rising CPM with flat CTR means the auction got more expensive; flat CPM with falling CTR means your creative got weaker.
CPC = CPM ÷ (CTR% × 10) 20.00 ÷ (2.4 × 10) = 0.83
Conversion rate, CPA, CAC and lead quality
Conversion rate
Conversion Rate = Conversions ÷ Visitors × 100 300 ÷ 12,000 × 100 = 2.5%
This calculator divides by visitors rather than sessions, giving a people-based rate: someone who converts on their third visit counts once in the denominator. Session-based rates run systematically lower on sites with heavy return traffic, and mixing the two is how two people end up arguing about a number they both calculated correctly.
CPA (cost per acquisition)
CPA = Ad Spend ÷ Conversions 5,000 ÷ 300 = 16.67
CPA prices the goal action, whatever you've defined that as — and that flexibility is the catch. A 16.67 CPA on newsletter signups and a 16.67 CPA on paid orders are different universes, and the label alone doesn't say which you're looking at.
CAC (customer acquisition cost)
CAC = Ad Spend ÷ New Customers 5,000 ÷ 80 = 62.50
CAC counts only people who paid, which makes it the stricter and more honest of the two. Here CPA is 16.67 and CAC is 62.50 — the gap exists because 300 conversions produced 80 customers. If you only ever look at CPA, that gap is invisible.
Lead-to-customer rate
Lead → Customer Rate = Customers ÷ Leads × 100 80 ÷ 200 × 100 = 40%
This is where lead quality shows up. A channel producing cheap leads that convert at 8% costs more per customer than one producing expensive leads that convert at 45%. When the rate drops while lead volume rises, you've usually loosened targeting rather than found new demand.
CPA vs CAC vs CPL — the distinction people get wrong
These three get used interchangeably in meetings, and the confusion costs money because they can point in opposite directions on the same campaign.
| Metric | Denominator | What it prices | Worked figure |
|---|---|---|---|
| CPL | Leads | One person who gave you contact details | 5,000 ÷ 200 = 25.00 |
| CPA | Conversions (any defined goal) | One completion of the action you chose | 5,000 ÷ 300 = 16.67 |
| CAC | New paying customers | One customer who actually paid | 5,000 ÷ 80 = 62.50 |
Cost per lead is a special case of CPA where the goal action is a lead, which is exactly what this calculator produces if you enter leads and leave conversions blank.
The practical rule: bid against the metric closest to money that still has enough volume to be stable. In a long B2B funnel with a handful of customers a month, CAC is too noisy to steer on weekly, so teams optimise to CPL or CPA and check CAC monthly. In ecommerce, where the conversion is the purchase, CPA and CAC nearly collapse into one number.
The failure mode is optimising a lead-stage metric while lead quality quietly falls. CPL down 30% and lead-to-customer rate down 50% is a worse quarter, not a better one, and only the customer-stage metric shows it.
Value metrics: AOV, LTV, LTV:CAC and ROAS
AOV (average order value)
AOV = Revenue ÷ Customers 20,000 ÷ 80 = 250.00
AOV is the quietest lever in the list: raising it through bundles, volume pricing or a higher tier improves CAC payback without touching a single ad. Averages hide skew, though — one enterprise deal in a month of small orders lifts AOV with no real change in customer behaviour.
LTV (simple lifetime value)
LTV = AOV × Purchase Frequency 250.00 × 2.5 = 625.00
Purchase frequency is purchases per customer over your chosen period. Enter it honestly — it's the one input the calculator can't derive for you, and the one people inflate.
LTV:CAC
LTV : CAC = LTV ÷ CAC 625.00 ÷ 62.50 = 10.0x
3x is the figure most often cited as a healthy target for subscription businesses — a rule of thumb rather than a law, resting on the idea that one customer's revenue should fund acquisition, delivery and overhead with something left. Because this LTV is revenue-based rather than margin-based, the ratio reads optimistically; discount it against your contribution margin.
A ratio far above target isn't automatically good news: 10x usually means you're underspending on demand you could profitably buy. It also ignores payback period, and twelve months to recover CAC strains cash flow whatever the eventual multiple.
ROAS in this calculator
ROAS = Revenue ÷ Ad Spend 20,000 ÷ 5,000 = 4.0x
ROAS appears here as one metric among twelve, from the same period figures. Because it uses revenue rather than profit, the ratio alone can't tell you whether the campaign made money — that turns on the variable cost of fulfilling each order, which this calculator doesn't ask for. The break-even threshold your margins imply is a separate calculation built around contribution margin.
Marketing KPI formulas: full reference
| Metric | Formula | Inputs needed |
|---|---|---|
| CTR | Clicks ÷ Impressions × 100 | Clicks, impressions |
| CPC | Ad Spend ÷ Clicks | Ad spend, clicks |
| CPM | Ad Spend ÷ Impressions × 1,000 | Ad spend, impressions |
| Conversion rate | Conversions ÷ Visitors × 100 | Conversions (or leads), visitors |
| CPA | Ad Spend ÷ Conversions | Ad spend, conversions (or leads) |
| CAC | Ad Spend ÷ New Customers | Ad spend, new customers |
| ROAS | Revenue ÷ Ad Spend | Revenue, ad spend |
| AOV | Revenue ÷ Customers | Revenue, new customers |
| LTV (simple) | AOV × Purchase Frequency | Revenue, customers, purchase frequency |
| LTV : CAC | LTV ÷ CAC | Revenue, customers, purchase frequency, ad spend |
| Lead → customer rate | Customers ÷ Leads × 100 | Leads, new customers |
| Pages per session | Page Views ÷ Sessions | Page views, sessions |
How to read the results
There are no universal benchmarks worth quoting. CTR, CPC and conversion rate vary by an order of magnitude between industries, between search and social, and between branded and non-branded traffic inside the same account. Any figure offered as "the average CTR" is an average over a sample you know nothing about; your own trend across the last six periods is the better reference.
What these metrics are genuinely good at is locating a problem. Because they sit in a chain, a change in one narrows down where the break is:
- CPA up, CTR down — creative or targeting. The ad is reaching people it doesn't speak to.
- CPA up, CTR steady, CPC up — the auction. Competition or seasonality raised the price of the same traffic.
- CPA up, CTR and CPC steady, conversion rate down — landing page, offer or pricing. Traffic held; something after the click broke.
- CAC up while CPA is flat — lead quality. Same volume of conversions, fewer of them buyers.
- Everything steady, revenue down — check AOV before touching a campaign. Mix shifted, not performance.
Three habits make the output trustworthy. Use one reporting window for every field, since a month of spend against a week of revenue produces nonsense. Enter one channel at a time, because a blended CAC across strong branded search and weak prospecting hides both. And check the volume behind anything you plan to act on — a conversion rate built on nine conversions moves eleven percent when one more person converts.