How marketing metrics impact your Profit and Loss statement: Beyond ROAS and MER

    Discover how marketing efficiency metrics like ROAS and MER affect your eCommerce Profit and Loss statement. Learn to calculate break-even MER and optimize ad spend for maximum profit.

    Updated October 29, 2024

    Finance

    Key takeaways

    • You shouldn't optimize marketing metrics like MER and ROAS in isolation. You need to consider how these metrics impact your profit and loss statement
    • Instead of taking the "up is good, down is bad" approach, you should ask yourself a more nuanced question: is my next dollar of ad spend going to earn me more profits?
    • Calculating your contribution margin and break-even MER helps you answer this question

    Develop a nuanced understanding of marketing efficiency

    Linked to the "grow top-line revenue at all costs'' phenomenon that gripped our industry was an obsession with maximizing ROAS (Return on Ad Spend) and MER (Marketing Efficiency Ratio). But this simplified "up is good, down is bad'' view can be damaging. The best brands have developed a more nuanced understanding of marketing efficiency, clearly recognising how these metrics impact their bottom-line.

    As we've outlined in a previous article, contribution margin is a critical part of any profitability equation, but it's completely absent from consideration on most ad platforms. Your marketing team wield a lot of power over the ultimate profitability of a business, so it would be a mistake to look at ROAS and MER in isolation. You need to consider how changes in these metrics flow through to your P&L.

    As a reminder, here are the formulas for MER and ROAS:

    marketing efficiency ratio (MER) = sales / ad spend

    return on ad spend (ROAS) = platform attributed sales / ad spend on that platform

    ROAS focuses on the platform-reported performance of individual campaigns, while MER is a more holistic company-wide measure of marketing efficiency. You should be monitoring these metrics closely to understand how marketing dollars are converting into product purchases. You can also use our benchmarking tool to assess your performance relative to industry peers and gauge a rough range for where you'd expect these metrics to be at.

    EXAMPLE OF MER BENCHMARKED AGAINST INDUSTRY PEERS
    mer-benchmarked

    If your primary goal is to generate as much revenue as possible, then put a laser focus on driving up MER and ROAS to get more sales per dollar of ad spend. But if you're looking to run a profitable business, you need to be wary of fixating on ad metrics alone and take your product margins into account.

    To illustrate this point, let's consider another side-by-side comparison:

    BIZ ABIZ B
    MER52.5

    BizA has a higher MER, so is a better business, right? Not so fast. Let's now reveal the margin profile of each business.

    BIZ ABIZ B
    Net selling price ($)100100
    minus variable costs
    Product cost6026
    Freight cost32
    Fulfilment cost166
    Transaction fees180135
    Gross profit2065
    Ad spend to acquire customer(s)2040
    Contribution margin per unit025
    %0%25%

    At a MER of 5.0, BizA are more efficient with their marketing, investing just $20 in ad spend to make a sale. BizB spend double this at a MER of 2.5 and $40 ad spend per sale. But taking margins into account paints a very different picture of the financial health of each business than MER alone does. Consider the break-even MER of each business, or simply put: how efficient they need to be with their ad spend just to break even per unit.

    break-even MER = selling price / gross profit

    BIZ ABIZ B
    Net selling price100100
    Gross profit2065
    Break-even MER51.54
    Actual MER52.5

    So, if we consider the actual MER for each business, BizB are actually exceeding their break-even MER and earn a contribution margin of $25 for each unit sold, while BizA are just about breaking even on each sale, not yet accounting for any fixed costs they need to cover.

    Assuming both brands sold 10,000 units and have fixed operating costs of $100,000, then BizA would be making a loss of $100,000 despite having the higher MER. Meanwhile, BizB make a $150,000 profit because their far superior gross margins have afforded them a lot of wiggle room with their marketing efficiency. Their ads are less efficient, but their business is more profitable.

    BIZ ABIZ B
    Contribution margin per unit025
    Units sold10,00010,000
    Total contribution margin0250,000
    Fixed operating costs100,000100,000
    Operating profit-100,000150,000

    This is where a nuanced view of marketing efficiency is crucial. If BizA blindly looked at marketing metrics alone and thought "Woah! Our MER is super high. Let's put an extra $50k into the ad budget!", they'd likely be compounding the problem and pushing themselves towards a negative contribution margin, since marketing efficiency tends to degrade as you increase spend. The reverse could happen to BizB. If they saw marketing efficiency decrease from say, 2.50 to 2.00, they might make a panicked decision to reduce their ad budget. But as we've seen, this would mean leaving profit on the table, because even at a MER of 2.00 they are exceeding their break-even point and earning a positive contribution margin per unit.

    Instead of taking the "up is good, down is bad" approach, you should ask yourself a more sophisticated question: is my next dollar of ad spend going to earn me more profits? Look at how your actual marketing efficiency compares to your break-even MER, not some arbitrary target.

    Calculate your break-even MER

    Use the calculator below to see how efficient you need to be with your marketing spend to generate a positive contribution margin. The gross profit figure is essentially your budget to acquire customers profitably. Stray beyond this and you risk adding unprofitable sales into your business.

    Break-even MER Calculator

    minus variable costs
    19
    Gross profit
    81
    Break-even MER
    1.23

    Look at the efficiency of individual campaigns too

    Up until this point, we've used the more holistic company-wide MER metric in our break-even calculations, but you can also assess this at the campaign or platform level with ROAS.

    Input the selling price and the gross profit figure you've calculated above. This generates a "break-even ROAS" for that particular campaign or platform. Then input your campaign spend and what the ad platform is reporting as the ROAS for said campaign. From this calculation, you can see the contribution margin you're generating from a given campaign. If this is negative, you may want to align objectives with your marketing agency. They should have very clear reason for spending unprofitably. "But our ROAS looks great" won't cut it.

    Campaign ROAS Calculator

    Break-even ROAS1.23
    Units sold1,000
    Ad spend per unit50
    Contribution margin per unit31
    Contribution margin from campaign31,000

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