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Google Ads Budget & Cost-per-Lead Calculator
Enter your own budget, cost per click, conversion rate, close rate, average sale value and gross margin. The calculator returns expected clicks, leads, cost per lead, sales, revenue, gross profit after ad spend, break-even cost per lead and ROAS, then shows what happens if your cost per click or conversion rate move 20% in either direction. Nothing is stored and there is no email gate.
Written by Sara Smith, Head of SEO, and reviewed by Lucas Durante, Founder, Odin Digital.
These are editable starting assumptions, not benchmarks. Replace every field with figures from your own account before you rely on the output.
Media spend only, excluding management fees.
From your Google Ads account, last 90 days.
Genuine enquiries divided by clicks.
Enquiries that become paying jobs.
Revenue from one closed job.
Revenue left after cost of delivery.
What — a month buys on your numbers
Expected clicks
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Expected leads
—
Cost per lead
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Expected sales
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Cost per sale
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Revenue
—
Gross profit
—
Revenue after cost of delivery, before ad spend.
Profit after ad spend
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Gross profit minus the budget.
Break-even cost per lead
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Gross profit an average lead is worth.
ROAS
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Revenue divided by ad spend.
Sensitivity: ±20% on conversion rate and cost per click
Each cell shows leads and cost per lead at that combination, on your budget. If a 20% worse conversion rate pushes cost per lead past break-even, the plan has no headroom.
| Conversion rate | CPC −20% | CPC as entered | CPC +20% |
|---|---|---|---|
| −20%— | — leads— per lead | — leads— per lead | — leads— per lead |
| As entered— | — leads— per lead | — leads— per lead | — leads— per lead |
| +20%— | — leads— per lead | — leads— per lead | — leads— per lead |
How the maths works
Google Ads is a chain of four multiplications. Your budget divided by cost per click gives clicks. Clicks multiplied by the click-to-lead rate gives enquiries. Enquiries multiplied by your close rate gives jobs. Jobs multiplied by average value gives revenue, and revenue multiplied by gross margin gives the profit the campaign actually produced before you subtract the media spend.
The number most operators ignore is the break-even cost per lead. Multiply your average sale value by your gross margin to get the profit in a job, then multiply that by your close rate. That is what one average enquiry is worth. Paying more than that per lead loses money regardless of how good the ROAS multiple looks, because ROAS is calculated on revenue and takes no account of what delivery costs you.
Work backwards mode reverses the chain. Enter the number of jobs you want, and the calculator divides by close rate to get leads, divides by conversion rate to get clicks, and multiplies by cost per click to get the budget the target implies. It is the honest way to answer "can we get 20 jobs a month from Google" before money is committed.
What moves each number
- Cost per click moves with keyword choice, match type, Quality Score, geography and time of day. Broad, high-intent commercial terms cost the most; specific service and problem phrases cost less and usually convert better.
- Click-to-lead rate is decided by the landing page far more than the ad: message match with the search, a phone number that is tappable, a short form, proof, and page speed on mobile.
- Lead-to-sale rate is mostly speed of response and who answers the phone. It has nothing to do with the ad account and everything to do with whether the enquiry is handled within minutes.
- Average sale value moves with what you quote for, not what you advertise. Campaigns pointed at your highest-value service change this figure faster than any bidding change.
- Gross margin sets the ceiling on everything above. Low-margin work needs a much lower cost per lead to survive, so it needs cheaper clicks or a better converting page, not a bigger budget.
Common mistakes
- Counting every phone-number click as a lead, which inflates the conversion rate and hides a poor cost per lead.
- Judging the account on ROAS alone while the margin makes that ROAS unprofitable.
- Planning on a peak-season conversion rate and funding it for twelve months.
- Including branded search in the account average, which flatters both cost per click and conversion rate.
- Raising the budget to fix a landing page problem, which buys more of the same result at the same cost per lead.
- Leaving management fees, call answering and GST out of the plan, then finding the campaign only breaks even.
Frequently asked questions
- How much should I spend on Google Ads each month?
- Work back from the maths rather than picking a round number. Decide how many sales you need, divide by your close rate to get the leads required, divide by your click-to-lead rate to get clicks, then multiply by your average cost per click. That figure is your budget. If it is higher than you can fund, reduce the keyword set or the geography rather than starving the whole account.
- What is a good cost per lead?
- A cost per lead is only good or bad relative to your own economics. Multiply your average sale value by your gross margin, then by your lead-to-sale rate. That is the gross profit an average lead is worth, and it is your break-even cost per lead. Anything meaningfully below it makes money; anything above it does not, no matter how it compares to someone else's number.
- Where do I find my real cost per click and conversion rate?
- Cost per click and conversion rate both sit in the Google Ads campaigns view once conversion tracking is set up. Use the last 90 days at account level, exclude branded search if you want a colder-traffic view, and only count conversion actions that represent a genuine enquiry — calls over 30 seconds, submitted forms, booked appointments — rather than every click on a phone number.
- Why does the calculator show a loss when my ROAS looks fine?
- ROAS is revenue divided by ad spend and ignores your cost of delivery. This calculator also reports gross profit after ad spend, which applies your margin before subtracting the budget. A 4x ROAS on an 18% margin loses money; a 2x ROAS on a 70% margin does not. Judge campaigns on profit after ad spend, not on the revenue multiple.
- How accurate is the sensitivity table?
- It applies a flat plus or minus 20% to cost per click and to click-to-lead conversion rate and recalculates on your own inputs. It shows how fragile a plan is: if a 20% worse conversion rate pushes cost per lead past break-even, the plan has no headroom and needs either better landing pages or a tighter keyword set before it launches.
- Do the results account for GST, agency fees or seasonality?
- No. The output covers media spend only. Add management fees, GST treatment and any call-answering or CRM costs to the budget field if you want a fully loaded view, and run the calculation twice — once on a peak month and once on a quiet month — if your demand swings seasonally.