Marketing measurement

Tracking revenue instead of form fills

Ad platforms optimise towards whatever you tell them is a conversion. Google’s own API reference describes Maximise conversions as a strategy that automatically maximises the number of conversions for a daily budget. If every form fill counts as a conversion, the system will look for more form fills, whether or not those people ever buy.

For a business that runs on enquiries, revenue tracking moves the target to a stage in your sales process: a qualified enquiry, a booked appointment, a signed order. Cost per lead can look healthy while cost per sale climbs, and I go through how that happens in why your best campaign by leads might be your worst by sales.

Purchase values for online shops

For an online shop the sale happens on the website, so the job is to record what each order was worth. In GA4 that is the purchase event, sent with the order’s value, its currency and a transaction ID; Google’s ecommerce guide marks the transaction ID as required for purchases and refunds. In Google Ads, a purchase conversion can pass each order’s own value instead of a fixed one, which Google says gives a more accurate sense of return on investment, and a unique transaction ID stops the same order being counted twice. Meta’s Pixel reference lists value and currency as required on every Purchase event.

If you run Shopping ads, there is one more step. Shopping ads are built from your Merchant Center product feed rather than keywords. Conversions with basket data add the products sold in each order, and with the cost of goods sold in the feed, Google Ads can report gross profit as well as revenue. That shows which campaigns earn money, not just which ones sell.

Offline conversions and CRM data

The sale usually happens away from the website, on the phone or in a meeting, and gets recorded in a CRM. Offline conversion tracking brings it back. Google identifies each ad click with a click ID such as a GCLID. You store that ID against the lead, and when the lead reaches a sales stage you send the stage back to Google Ads. Google’s developer documentation recommends pairing the click ID with customer-provided details through enhanced conversions for leads, and describes imports that rely on the click ID alone as the legacy option.

Meta works in a similar way through its Conversions API, a connection between your own server or CRM and Meta. For Instant Form lead ads, its Conversion Leads goal lets Meta optimise towards a CRM stage you send back.

I have seven CRMs connected so that revenue can be traced back to the marketing that produced it. The practical steps for Google are in getting offline sales back into Google Ads, and the Meta side is covered in the Meta Conversions API guide for lead generation.

Enhanced conversions

Enhanced conversions add first-party details a customer has already given you, such as an email address or phone number, to a conversion record. For the website version, the email, phone, name and street address are hashed with SHA-256 before they are imported. For leads, the hashed details captured on your form are sent again when you upload the sale, and Google matches them to the same data from your website and to signed-in users who engaged with the ad, which it says improves both accuracy and bidding performance (see the offline conversions guide).

Two limits matter. Hashing is a privacy safeguard, but the ICO lists hashing as a pseudonymisation technique and says pseudonymised data is still personal data for anyone who holds the information needed to link it back to a person. And if a visitor denies the ad_user_data consent signal, Google stops collecting the hashed data used for enhanced conversions.

Consent and signal loss in the UK

In the UK, storing or reading information on someone’s device for online advertising needs consent, and the ICO says ad measurement falls within that same consent. Google also applies its EU user consent policy to users in the UK, which requires legally valid consent and records of it.

Consent Mode is how a cookie banner passes those choices to Google tags, using four signals: ad_storage, analytics_storage, ad_user_data and ad_personalization. When ad_storage is denied, Google Ads cookies are neither written nor read. In advanced mode, tags still send cookieless pings, and Google uses them to model some of the missing measurement once a data threshold is met.

This is one source of signal loss in the UK. The ICO’s May 2026 report to government notes that 99% of the UK’s top 1,000 websites now give people an equal choice to accept or reject, and that an increased proportion of people are rejecting. Each visitor who rejects is someone whose later conversion the ad platforms may not see directly. The checks I’d suggest are in Consent Mode and enhanced conversions: a UK checklist.

Server-side tracking

Server-side tagging moves tag processing out of the visitor’s browser and onto a server container you control, so you decide how data is shaped and where it goes before any vendor receives it. Google’s documentation gives less work for the browser, the option to anonymise or block data before forwarding it, and more durable first-party cookies as reasons to use it. A lighter option, Google tag gateway for advertisers, loads Google’s scripts from your own domain.

What server-side tracking does not do is remove the need for consent. In Google’s own setup, the banner choice is collected on the website and passed to the server container, and the server-side tags adjust what they send. On the Meta side, the advice is to run the Conversions API alongside the Pixel and deduplicate the two with a shared event ID and event name.

Reporting that ends in a decision

The last part is reporting. My view is that this is where a lot of good tracking goes to waste. A report that lists sessions, clicks and leads describes the month. A report that shows cost per sale or return on ad spend by campaign, explains the biggest change and names a decision with an owner shapes the next month.

Monthly GA4 reports for 36 websites are drafted automatically on my side, then checked by a person before they are sent. The format I’d suggest is set out in the one-page GA4 report people actually read.