Rex says
Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.
Try a scenario
Click to load — tweak from there.Inputs
Result
Blended CAC
$40.00
MER (revenue ÷ spend)
4.00
Marketing spend as % of revenue
25.0%
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One click, a permanent link with your numbers baked in.
How to use this
- 1Enter total marketing spend (period) ($).
- 2Enter total revenue (same period) ($).
- 3Enter new customers acquired.
- 4Read your blended cac on the right — it updates as you type.
- 5Hit Share to keep the scenario or send it to someone.
About this calculator
Channel-level ROAS gets distorted by attribution — a customer who saw a Meta ad, searched on Google, then bought through email gets credited multiple times or not at all depending on the platform's model. Blended CAC and MER solve this by looking at total marketing spend across every channel against total revenue and total new customers for the same period, giving you a number that can't be gamed by attribution windows. This calculator takes your total marketing spend for a period, total revenue for that period, and total new customers acquired, and computes blended CAC (spend ÷ new customers) and MER (revenue ÷ spend). Enter total spend across all paid channels, total revenue including repeat customers, and new customer count for the same window. The output shows blended CAC, MER, and the implied average order value contribution needed to be profitable, which is the real health check for your marketing efficiency versus any single platform's self-reported ROAS.
Worked example
Using the values the calculator loads with:
Inputs
- Total marketing spend (period): 18000 $
- Total revenue (same period): 72000 $
- New customers acquired: 450
Results
- Blended CAC: $40.00
- MER (revenue ÷ spend): 4
- Marketing spend as % of revenue: 25.0%
What each field means
Inputs
- Total marketing spend (period) ($)
- The total marketing spend (period) used in the calculation, measured in $. Starts at 18000 $ so you have a working example on load.
- Total revenue (same period) ($)
- The total revenue (same period) used in the calculation, measured in $. Starts at 72000 $ so you have a working example on load.
- New customers acquired
- The new customers acquired used in the calculation. Starts at 450 so you have a working example on load.
Results
- Blended CAC
- Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- MER (revenue ÷ spend)
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Marketing spend as % of revenue
- Returned as a percentage. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
Why use MER instead of platform-reported ROAS?
Platform ROAS is self-attributed and inflated by overlapping attribution windows across Meta, Google, TikTok, and email. MER uses your actual total revenue and total spend from your own financial data, so it can't double-count a conversion the way multiple platforms claiming credit for the same sale can.
What's a healthy MER for a growing DTC brand?
Most established brands run MER between 2.5 and 4.5 depending on margin structure; higher-margin categories like apparel or beauty can sustain lower MER (more spend relative to revenue) than thin-margin categories like food or low-cost commodities.
Does blended CAC include organic and repeat customers?
This version only counts new customers in the denominator, which is standard for CAC. Revenue in the MER calculation typically includes total revenue (new plus repeat), which is intentional since a lot of paid spend indirectly drives repeat purchase behavior too.
How often should I calculate blended CAC and MER?
Weekly for fast-moving paid social spend and monthly for a stable trend line. Daily numbers are too noisy given normal week-to-week conversion variance, but waiting a full quarter means you react to problems too late.
Accuracy and limitations
- Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
- Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
- This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.
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Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Blended CAC vs MER Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/blended-cac-mer
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/blended-cac-mer" target="_blank" rel="noopener">Blended CAC vs MER Calculator — RevenueLab</a> (2026).</p>
Source: [Blended CAC vs MER Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/blended-cac-mer) (2026).