Marketing Efficiency Ratio (MER): How to Calculate It and What a Good Number Is

Marketing Efficiency Ratio (MER): How to Calculate It and What a Good Number Is

Marketing efficiency ratio (MER) is your total revenue divided by your total marketing spend over the same period. If you made $120,000 in revenue and spent $30,000 on marketing, your MER is 4.0. It ignores which ad platform claimed the sale, which is exactly why it is useful and exactly why it is not enough on its own.

This guide shows you how to calculate MER, how to work out what number you actually need, how it differs from ROAS, and where it misleads business owners who rely on it alone.

TL;DR

• MER = total revenue ÷ total marketing spend, for the same period. It is blended, so no platform attribution is involved.
• A “good” MER is not a universal number. Your breakeven MER is 1 ÷ the share of revenue you keep before ad spend (your contribution margin).
• MER is a health check for the whole business. ROAS is a diagnostic for individual campaigns. You need both, and both should be reconciled to closed revenue in your CRM.
• MER can hide wasted spend, especially when brand search and repeat customers carry the average. Track new-customer MER separately.

Table of Contents

• What MER measures, and what it doesn’t
• How to calculate MER step by step
• What is a good MER? Start with your breakeven
• MER vs ROAS: which one should you use?
• Where MER misleads you
• Perspective: why we start with MER and never end there
• Using MER to set budgets without guessing
• Getting the data right first
• Need a second opinion on your numbers?
• FAQ
• Sources

What MER measures, and what it doesn’t

MER takes the top line of the business and divides it by what you spent to get it. Revenue in the numerator is everything: paid, organic, email, direct, repeat customers, referrals. Spend in the denominator is your marketing cost.

That makes it a blunt but honest number. It can’t be inflated by two platforms both claiming the same sale, which is a common problem when Google Ads and Meta Ads are each reporting their own conversions. Practitioners lean on blended measures partly because platform attribution has become harder to trust: Australian industry submissions to the ACCC point to privacy changes such as the restriction of third-party cookies and Apple’s App Tracking Transparency as undermining traditional platform-based attribution.

What MER can’t tell you is which campaign is working. A MER of 4.0 could mean every campaign is solid, or that one brand search campaign is doing all the work while a prospecting campaign burns money. The average hides the gap, and the gap is where the wasted spend sits.

How to calculate MER step by step

The formula is simple. The discipline is in choosing the inputs and keeping them consistent.

1. Pick a period. A month is the usual choice. For businesses with long sales cycles (law firms, B2B services, solar installers), use a rolling 90 days so revenue lines up with the spend that generated it.
2. Take total revenue for that period. Use revenue excluding GST. Pull it from your accounting software or CRM, not from an ad platform dashboard.
3. Take total marketing spend. At minimum, all ad spend: Google Ads, Meta Ads, Microsoft Ads and any others. Many businesses also add agency fees, freelancers and creative costs. Either approach is valid. Pick one and don’t change it.
4. Divide revenue by spend.

A worked example

An Australian eCommerce business selling homewares has these numbers for a month (illustrative figures, not a client result):

For every dollar spent on marketing, the business took four dollars of revenue. Whether that is good depends on the next section.

Watch the convention

Some sources flip the formula and divide spend by revenue, which gives a percentage (here, 25%). Triple Whale, for example, notes that many marketers report the revenue-over-spend version as a multiplier and advises you to confirm which convention a benchmark uses before comparing. In this guide, MER is always revenue ÷ spend.

What is a good MER? Start with your breakeven

You will see round-number benchmarks quoted online, such as “aim for 3 or 4”. Ignore them until you know your own margins. A MER of 3.0 is profitable for a business with an 80% contribution margin and a loss-maker for one at 25%.

The working formula:

Breakeven MER = 1 ÷ contribution margin

Contribution margin here is the share of each revenue dollar left after product cost, delivery, merchant fees and anything else that scales with each sale, but before marketing.

In the homewares example, if the contribution margin is 40%, the breakeven MER is 2.5. A MER of 4.0 means the business is comfortably above water on a blended basis. That gives you room to scale spend, as long as the marginal dollar keeps performing.

Overheads change the target

Breakeven on contribution margin only covers the cost of the ad dollars. If you also need to cover wages, rent and software, your target MER sits above breakeven. Work backwards: decide the profit you want from marketing-driven revenue, then set the MER that delivers it.

MER vs ROAS: which one should you use?

Both are revenue-over-spend ratios. The difference is scope.

Use MER to answer “is marketing paying for itself overall?” Use ROAS to answer “which campaign should get the next dollar?” The trouble starts when ROAS is taken straight from the platform. Advertising platforms have a vested interest in their own numbers looking good, and the AANA’s submission to the ACCC stresses the need for independent measurement of advertising performance. In practice, that means reconciling platform-reported results to your own sales records.

If you want a deeper look at why dashboards disagree with your bank account, we cover it in why your Google Ads reporting is probably lying to you.

Where MER misleads you

MER is honest about totals and silent about composition. Four situations catch businesses out.

Brand search and repeat customers carry the average

A customer who already knows you searches your name, clicks your ad and buys. That sale lifts MER, but it was not created by your advertising. If you have a Google Ads campaign aimed at new customers that also bids on your brand name, the numbers will flatter it.

The fix is to split brand from non-brand and to exclude brand terms from acquisition campaigns. Then watch MER for new customers on its own: new-customer revenue divided by acquisition spend. If blended MER is 4.0 and new-customer MER is 1.4 against a breakeven of 2.5, you have a business living off its existing customer base while paying to acquire customers at a loss.

Leads counted twice

If your revenue figure comes from a CRM and your lead count comes from two ad platforms, the same person can appear three times: once in Google, once in Meta, once in the CRM. MER built on CRM revenue avoids this, but any channel-level breakdown you add underneath needs each lead counted once. That means passing the click ID (GCLID for Google, fbclid for Meta) into the CRM so each lead is tied to a single source. Our guide to capturing GCLID and fbclid for closed-loop attribution covers the setup, including the privacy considerations.

Timing gaps

A campaign running this month may produce revenue in three months. For trades quotes, legal matters, telehealth onboarding or B2B pipeline, a single month of MER is noisy. Use a rolling window that matches your sales cycle.

Revenue that isn’t marketing-driven

A big wholesale order, a one-off contract or a seasonal spike can push MER up without any change to ad performance. Note the context when you report it.

Perspective: why we start with MER and never end there

We get called in when an owner says the agency report shows a ROAS of 6 and the bank account says otherwise. Nine times out of ten, the platform tells a good story and the CRM tells a different one.

Our approach is the same every time. We fix tracking first, because no ratio is worth anything if conversions are double-counted or missing. Then we cut the spend that isn’t pulling its weight, which usually means brand terms running inside acquisition campaigns, search terms nobody has reviewed, and retargeting audiences that mostly contain people who were buying anyway. Then we measure every campaign against closed revenue in your CRM.

MER is the sanity check in that process. If platform ROAS says 6 and MER says 2.1, one of them is wrong, and it is rarely MER. We would rather you see an uncomfortable blended number than a flattering platform one.

On Google Ads, we run exact and phrase match with tight negatives and regular search term reviews. We don’t recommend broad match. Broad match hands the platform the decision about which searches deserve your money, and your blended MER is the first place the leak shows up.

On Meta Ads, we’ve seen MER do real work. One DTC supplement brand we manage grew from $15k to $90k a month in revenue on Meta Ads, and the way we knew it was real growth rather than a reporting artefact was that blended numbers moved with the platform numbers. We make no promises that your results will match. What we can promise is that we will tell you upfront if we can’t help.

— Jesse Lees

Using MER to set budgets without guessing

Once you know your breakeven and your current MER, MER becomes a budgeting tool.

1. Set a floor. Your breakeven MER is the floor. Below it, you lose money on each marketing dollar, unless you are deliberately buying customers whose lifetime value justifies it.
2. Set a target. Add a margin of safety for overheads and profit. If breakeven is 2.5, you might target 3.5.
3. Increase spend in steps. Raise budget by a modest amount, wait for a full conversion cycle, then check whether MER held. Expect it to fall as you scale, because the marginal customer costs more than the average one.
4. Stop when marginal MER hits your floor. Compare the extra revenue from the extra spend. If spend rose by $5,000 and revenue by $9,000, the marginal MER is 1.8. That is below a 2.5 breakeven, even if the blended number still looks healthy.

This last step is the one most owners skip. Blended MER falls slowly while marginal MER falls fast, which is how a business ends up spending well past the point of profit.

Getting the data right first

MER needs only revenue and spend, so it feels safe from tracking problems. It is not, for two reasons. First, the breakdown that makes MER actionable (new vs returning, brand vs non-brand, channel vs channel) depends on clean tracking. Second, the broader Australian picture suggests most businesses aren’t there yet: the ABS found that in 2024-25 only 7% of Australian businesses actively measured the contribution of digital activities to business performance, up from 3% in 2021-22.

Google’s own Australian research with Econsultancy found that top-performing marketers focus on bottom-line sales and profit rather than clicks and conversions. It also notes that measurement gaps across devices and channels never fully close, so the aim is reliable benchmarks rather than perfect attribution. That is a fair description of what MER gives you.

A practical checklist before you trust any ratio:

• Your CRM or accounting system is the source of truth for revenue.
• Conversions in Google Ads and Meta line up roughly with real enquiries or orders. If they don’t, start with Google Ads conversion tracking.
• Offline sales (phone orders, in-store, closed deals) are fed back to the platforms or at least reconciled against them. Our pipeline attribution audit guide walks through this for lead-generation businesses.
• Brand campaigns are separated from acquisition campaigns.
• Follow-up of leads is consistent. A good MER can be wrecked by leads that go cold, so if you run a trade business, a follow-up cadence for leads is worth sorting out before you raise spend.

Different business types, different MER stories

eCommerce and DTC. MER is the headline metric, because order data is clean. Watch new-customer MER and returning-customer share. Our ecommerce conversion rate guide covers measuring before you spend more.

Trades and home services. Revenue arrives after a quote, sometimes weeks later. Use a rolling window and measure against jobs won, not form fills.

Law firms, healthcare and professional services. Matter or patient value varies widely. Use average revenue per closed client and a longer window. A telehealth provider we work with added 600+ new patients in 12 months through Google and Meta Ads, and the numbers that mattered were new patients booked, not clicks.

Multi-location businesses. Calculate MER per location where you can. A strong average often hides one weak branch.

Need a second opinion on your numbers?

If your MER and your platform ROAS tell different stories, or you can’t confidently calculate MER because the data is scattered, a Google Ads audit is the quickest way to find out where the gap is. It costs $99 AUD one-off. We check conversion tracking, brand and non-brand overlap, search terms, and how reported conversions compare to real sales. If the tracking is the problem, we can fix it through our website tracking service before you spend another dollar.

FAQ

What is a good marketing efficiency ratio?

It depends on your margins. Divide 1 by your contribution margin to get your breakeven MER, then set a target above it to cover overheads and profit. A business with a 40% margin breaks even at 2.5, so a MER of 4.0 is healthy, while the same 4.0 would only just break even at a 25% margin.

How do I calculate MER?

Divide total revenue (excluding GST) by total marketing spend for the same period. Use revenue from your accounting system or CRM, and decide once whether agency fees and creative costs count as marketing spend. Keep that definition fixed so month-to-month comparisons stay meaningful.

What is the difference between MER and ROAS?

MER uses all business revenue and all marketing spend, with no attribution. ROAS uses the revenue a single platform or campaign claims, divided by the spend on it. MER tells you if marketing pays overall, and ROAS helps you decide where to put the next dollar. Treat platform ROAS with caution until it has been reconciled to your CRM.

Is MER the same as blended ROAS?

In most explanations, yes: both are total revenue divided by total marketing spend. Some sources flip the formula and express spend as a percentage of revenue, so check the convention before comparing your number to a benchmark.

Should I track MER weekly or monthly?

Monthly is the right default for most businesses, because weekly figures swing with promotions and payment timing. If your sales cycle is long, use a rolling 90-day view. Weekly checks make sense only for high-volume eCommerce stores with steady order flow.

Sources

• Characteristics of Australian Business, 2024-25 financial year, Australian Bureau of Statistics
• Submission from the Interactive Advertising Bureau (IAB) Australia to the ACCC
• Submission from the Australian Association of National Advertisers (AANA) to the ACCC
• Think with Google and Econsultancy: Australian marketing measurement
• What is marketing efficiency ratio (MER), Triple Whale

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