Google Ads for UK e-commerce:
profit-first measurement & KPIs
Most e-commerce accounts are optimised to make Google's reports look good. Profitable accounts are optimised around the P&L - contribution margin, new-customer acquisition cost and payback - and treat the platform's headline numbers as a directional, not the goal.
This is the hub for measuring Google Ads the way a finance team would. Start with the core metrics below, run your own numbers through the calculator, then read the deep dives when you want the detail.
The short answer
Profit-first measurement means judging Google Ads on the profit it generates, not the revenue it reports.
Instead of running an account to a blended ROAS target, you anchor every decision to four numbers: contribution margin (what's left after product, fulfilment and transaction costs), breakeven ROAS (the revenue-per-pound where the account stops losing money), new-customer acquisition cost (NCAC - what you actually pay to win a first-time buyer), and your payback window (how long before that customer turns profitable).
ROAS still has a place. It's just a platform metric - useful for steering bids, useless as a definition of success. The accounts that scale profitably are the ones where the target is derived from real margins, not borrowed from someone else's case study.
The metrics, one at a time
Supporting guidesThe Google Ads KPIs that actually matter
ROAS is a platform metric, not a business one. The KPIs to run your account on, how to set tROAS targets off real margins, and why optimising for Google's numbers often works against your P&L.
What's a good ROAS for my account?
There's no universal number. A "good" ROAS is the one that clears your breakeven with margin to spare. How to work out yours instead of borrowing a benchmark off a webinar slide.
How to calculate your breakeven ROAS
The line in the sand every target sits above. A plain walkthrough of the breakeven calculation using contribution margin - the foundation the other KPIs are built on.
How to actually calculate your NCAC
Cost per acquisition lumps new and returning customers together and flatters your numbers. How to isolate new-customer acquisition cost so you can see what growth really costs - and steer Google toward it rather than toward easy repeat sales.
Contribution margin, explained
The number that should sit underneath every Google Ads decision - what it is, what to include and exclude, and why it's the honest alternative to gross margin when you're setting a target.
Common questions
Profit-first measurement, answered
Optimising the account around the profit it produces rather than the revenue Google reports. Decisions are tied to contribution margin, NCAC, cashflow, payback windows and SKU purposes - not a blended ROAS target lifted from a benchmark. The platform's numbers become an input, not the scoreboard.
ROAS tells you revenue per pound spent, but it ignores margin, returns, discounting and whether a customer is new or repeat. Two accounts on an identical ROAS can have completely different profitability. It's a useful lever for steering bids - it's just not a definition of success.
It's the revenue-per-pound figure where the account neither makes nor loses money, derived from your contribution margin. If your contribution margin is 40%, your breakeven ROAS is 2.5 - you will aim for your profit-focused campaigns to achieve greater results than this - verified by backend data (not in-platform). The unit economics calculator works it out for you.
CAC blends new and returning customers, so a strong repeat base can quietly hide expensive acquisition. NCAC isolates what you pay to win a first-time buyer - the number that tells you whether growth is actually affordable, and the one Google's defaults rarely optimise toward on their own.
Gross margin stops at cost of goods. Contribution margin keeps going - it strips out the variable costs that move with each order (fulfilment, payment fees, packaging) to show what's genuinely left to cover ads and overhead. It's the honest base for any ROAS target.
If the account is profitable, good - but a ROAS that looks healthy can still be leaving money on the table or scaling unprofitably at the margin. Measuring on contribution and NCAC tells you whether your next pound of spend is actually worth spending, which is the only question that matters once you want to grow.
Work with Kiezo Growth
Most new clients start with an audit - the lowest-risk way to see exactly how your account is performing against your P&L before committing to anything ongoing.
Audit
Account & Feed Audit
One-off · From £2,500
- Find exactly where your account is leaking profit vs. just showing poor platform metrics
- SKU-level analysis - which products drive real margin vs. burning budget
- Full GMC feed review: attribute coverage, alignment to search behaviour, tailored for business needs
- Delivered with prioritised fixes, not a long list of observations
- No obligation to continue - you own the audit
Account Management
Ongoing Account Management
Monthly retainer · From £3K · 3-month initial term, then rolling
- Audit included
- Senior specialist managing your account - not passed off to a junior focusing on ROAS
- Contribution margin and NCAC as the actual north stars, tied to your P&L
- Flat fee means I'm incentivised to grow your profit, not your spend
- Daily Slack comms. Weekly performance updates. QBRs in person if requested.
- You always own the account and the data.
All services are flat fee. No percentage of ad spend. No markup on budget. No kickbacks off growing your spend. That's not a policy - it's a structural commitment to alignment.