Google Ads Waste Calculator

How the calculator works

Three waste categories, all calculated from your inputs — no made-up industry averages. Here's the math:

1. Unprofitable acquisition cost

This is the clearest, hardest form of waste: every conversion you're acquiring above break-even CPA loses money directly.

If your actual CPA is £60 and you only generate £42 of gross profit per order (£120 AOV × 35% margin), every conversion costs you £18. Multiply by monthly conversions — that's direct, unrecoverable waste.

2. Quality Score / CPC premium

Google charges lower CPCs to advertisers with higher Quality Scores — and the biggest input to Quality Score is expected CTR. Accounts with below-benchmark CTR pay a premium on every click.

A 3% CTR is a reasonable baseline for a well-structured search account. If your CTR is below that, the calculator estimates your CPC premium as a linear function of the gap, capped at 25% of spend. If your CTR is at or above 3%, this component is £0.

This is an estimate of recoverable spend, not a guarantee — but it's a useful target for negative keyword and ad relevance work.

3. Landing page gap

If your landing page converts below 3% (a reasonable mid-market ecommerce benchmark), you're paying for clicks that should convert but don't. The "waste" here is the profit you'd earn if those extra clicks converted — not the spend itself (you already paid for the clicks).

This is opportunity cost, not direct waste — but it often dwarfs the first two categories in real accounts. A clean landing page fix is usually the highest-leverage lever available.

A note on the total

The three categories aren't strictly independent — fixing CTR lowers CPC, which lowers CPA, which can reduce the first category. Treat the total as a ceiling estimate of recoverable spend, not a fully additive sum. The value of the breakdown is identifying where the biggest single lever is, not the exact £ recoverable.

Where the 3% benchmarks come from

Both 3% CTR and 3% CR are used as reference points throughout the calculator. They're not universal truths — they're widely-cited mid-market search benchmarks and they give consistent, conservative estimates. If your account is in a niche where benchmarks differ (e.g. luxury ecom at 0.8% CR, niche B2B at 0.5% CTR), treat the output as directional, not prescriptive.

How to reduce your ad waste

1. Pull a 90-day search terms report and add every irrelevant query as a negative keyword. This is the single fastest lever — most accounts find 20%+ of spend going to queries they'd never want to bid on.
2. Audit Quality Score account-wide. Any keyword with QS ≤ 5 is costing you a CPC premium. Pause or rebuild the ad groups.
3. Fix conversion tracking. If the calculator shows unprofitable CPA but you're confident the account performs well, Google is likely optimising toward the wrong signals.
4. Rebuild the landing page if your CR is below 2%. See our guide to high-converting ecommerce landing pages.
5. Tighten match types. If you're running broad match without a deep negatives list and smart bidding at tROAS, you're feeding Google freedom without guardrails.

Deeper read: Where Google Ads Accounts Waste Money (And How to Find It).

Related tool

If you want to calculate forward-looking ROAS and break-even rather than current waste, use the Google Ads ROAS Calculator.