Lightdrop

The 1-page MER tracker

Your ROASis lying.

Every ad platform counts the sales it touched, so one $120 order can show up three times. MER uses two numbers that can't double count — your total revenue and your total marketing spend. Check yours below in two minutes.

Check your MER
One sale. Three dashboards take credit.
Credit ✓Social ads1Sale
Credit ✓Search ads1Sale
Credit ✓Email1Sale

= 3 sales

Your bank disagrees.

Bank statement

Sales
1
Revenue
$120

1 sale.

Thank you

The formula

MER, or Marketing Efficiency Ratio.

MER

=

Total revenue

Total marketing spend

↑ From your bank, not your dashboards

e.g. $40k ÷ $10k = 4

Total revenue

Every sale from every channel that week. Pull it from your store or your bank, never from an ad platform.

Total marketing spend

Every marketing dollar that week: all ad platforms, plus creators, agencies and tools if you count them. Decide what's in once, then keep it the same.

Dashboards grade their own homework. MER checks it.

How to read it

Three rules.

  1. 01

    Check it weekly.

    Same day, same two numbers, every week. Daily is too noisy. Monthly is too late.

  2. 02

    Spend up, MER steady→ scaling.

    You're putting more in and the return is holding. That's healthy growth, so keep going.

  3. 03

    ROAS up, MER down→ someone's taking credit.

    The dashboards say it's working. Your bank says it isn't. Find what changed before you spend more.

Check your MER

Two numbers. No dashboards.

Add this week's total revenue and total marketing spend. Add last week's too, and you'll see which rule you're in. Nothing is saved, so come back and check again next week.

This weekLast week (opt.)Total revenueTotal marketing spendDashboard ROAS

Your floor (optional)

Margin before marketingWhat's left of each sale after product, shipping, fees and returns.
Profit you want to keepYour profit goal, as a share of revenue.

Showing an example. Type your numbers to check yours.

MER · This week

Example

3.59

$52,000 ÷ $14,500

Vs last week

MetricLastThisChange
Revenue$57.5k$52k−9.6%
Spend$14.5k$14.5k0%
MER3.973.59−9.6%
Dash. ROAS4.2x4.9x+16.7%
Taking credit?

Rule 03: ROAS up, MER down. Your dashboards say it's working and your bank doesn't. Find what changed before you spend more.

Vs your floor

Break-even MER
1.82
1 ÷ 55%
Target MER
2.50
1 ÷ (55% − 15%)
On target

You're above the 2.50 you need to keep 15% profit.

Work with Lightdrop

Want a partner on your numbers?

We build the marketing infrastructure ambitious brands run on, then we operate it with you.

Work with us