The share of your ad budget each channel spends is not a performance metric. It mostly reflects the budgets you set. To decide where the next dollar goes, divide each channel's spend by the customers it produced, and compare that.
A founder of an AI startup brought a channel report to a mentoring call. It had been generated with an AI tool and listed, for each platform, its percentage of total spend. The reading on offer was that the channel using the most budget must be the one to keep funding. We pushed back hard, and the founder agreed it was a strange number to track.
A worked example
We sketched the numbers on the call. They're illustrative, not real results. Say a month's spend is $10,500 and the goal is paying customers who start with a trial sign-up:
- Google: $3,500, about 33% of spend. 5 trial sign-ups at $700 each. 2 became customers, so $1,750 per customer.
- Meta: $2,000, about 19% of spend. 25 trial sign-ups at $80 each. 3 became customers, so about $667 per customer.
- LinkedIn: $5,000, about 48% of spend. 3 trial sign-ups at about $1,667 each. 1 became a customer, so $5,000 per customer.
Read by share of budget, LinkedIn looks like the main channel and Meta the minor one. Read by cost per customer, it's the opposite. Meta spent about a fifth of the budget and produced the cheapest customers. LinkedIn spent about half and produced the most expensive one.
Why share of spend says so little
You set the budgets, and the platforms pace them. Google Ads, for example, shifts spend toward days when clicks and conversions are more likely, so a campaign can miss its average daily budget one day and exceed it the next, while monthly spend stays within 30.4 times the daily figure for most campaigns. A channel's share of the total is mostly those inputs played back to you.
Cost per conversion is a better start. Google defines cost per action as the total cost divided by the number of actions. The catch is the action you told the platform to count. It's usually a sign-up or a form, not a sale, so the cheapest sign-ups and the cheapest customers won't always come from the same channel. Here Google's sign-ups cost almost nine times Meta's, while its customers cost under three times as much.
Get the customer number into the report
- Keep optimizing to the sign-up. We usually point campaigns at the trial or inquiry, since purchases alone are often too few for the platform to optimize on.
- Judge on customers. Count how many customers each channel produced that month and divide its spend by that.
- Feed customers back. Google's offline conversion import measures what happens after the click, such as a signed contract. Google recommends enhanced conversions for leads if you're starting fresh, as covered in teaching Google who actually closed.
- Mind small numbers. One customer more or less moves a low-volume channel a long way. See why your best-converting campaign might have made almost no sales.
The takeaways
- Share of budget reflects the budgets you set and how the platform paces them.
- A channel spending a fifth of the budget can produce your cheapest customers.
- Check cost per conversion first, then decide budget on cost per customer.
- Import customers back into the platforms so they see more than sign-ups.
- Give low-volume channels time before you cut or scale them.
Common questions
Is percentage of budget spent a useful ad metric?
Only as a pacing check, in our view. It tells you whether each channel spent what you planned. It says nothing about whether that spend produced customers, so it shouldn't decide where the next dollar goes.
How do I compare Google Ads, Meta and LinkedIn performance?
Divide each channel's spend by the customers it produced in the same period. Cost per conversion, for the action you told each platform to count, is the first check. Cost per customer is the one that decides budget when sign-ups and customers aren't the same thing.
Why does Google Ads spend more than my daily budget?
Google optimizes spend toward days when clicks and conversions are more likely, so on some days you won't reach your average daily budget and on others you'll exceed it. Across a month, it limits spend to 30.4 times your average daily budget for most campaigns.
How do I get customers, not just sign-ups, into Google Ads?
Import them. Google's offline conversion import lets you measure what happens after the ad click, such as a signed contract. If you haven't set it up yet, Google recommends starting with enhanced conversions for leads, which uses hashed customer data such as email addresses.
What if a channel only produced one customer?
Treat its cost per customer as a direction, not a verdict. One customer more or less can swing the number a lot, so give low-volume channels more time before you cut or scale them.