% Custom Expenses Ad Spend
The share of sales going to marketing costs no ad platform ever reports.
What it means
% Custom Expenses Ad Spend is the share of Total Sales taken by the custom expenses you marked as Ad Spend in Cost Settings, as a percentage. Both fixed and variable entries count, and only the ones you tagged as advertising are in it.
This is the marketing money the ad platforms never see: agency retainers, creator fees, affiliate payments, a photographer for the campaign. Meta and Google report what you paid Meta and Google. This reports everything else you decided was advertising.
Show the math
Formula and a worked example
Custom Expenses Ad Spend is the sum of your fixed and variable custom expenses marked as Ad Spend for the period.
Total Sales is Gross Sales + Shipping + Tax − Discounts − Refunds.
Worked example. A month takes €200,000 of Total Sales. You paid an agency €6,000 and creators €4,000, both tagged as Ad Spend, so the total is €10,000. % Custom Expenses Ad Spend = 10,000 ÷ 200,000 = 5%.
The platforms billed €50,000 that month, which is a MERMERWhole-business marketing efficiency across every channel.Under 30% is healthy of 25%. Add the tagged €10,000 and True Ad Spend is €60,000 — 30% of sales. That five-point gap is the whole reason this column exists: it's the part of your marketing bill that no ad account will ever show you.
It answers the question
How much of every sale goes to marketing that isn't a platform invoice? It's the difference between what your ad accounts say you spend and what you actually spend.
Why it matters
Most efficiency decisions are made on platform numbers alone, and platform numbers are incomplete for anyone paying an agency or a creator. A store congratulating itself on a 25% MER while quietly spending another five points off-platform is running a 30% business and steering by the wrong figure.
It also makes fixed marketing costs visible. A retainer is charged in full whether the month was strong or catastrophic, so this ratio climbs hardest in the months you can least afford it — the same way rent does, but sitting in a line most owners think of as variable.
The number is only ever as good as your tagging. Every euro of it comes from something you entered and ticked, so an empty reading tells you about your Cost Settings before it tells you about your marketing.
What good looks like
There are no published bands for this one, and a universal target wouldn't mean much: a store that runs everything in-house should read close to zero, and a store whose growth is built on creators can carry several points here and be perfectly healthy. Judge it against your own months.
Two readings do mean something on their own. A number that never moves while sales swing is a fixed cost, and worth naming as one. And this share climbing while MERMERWhole-business marketing efficiency across every channel.Under 30% is healthy stays flat means your true marketing cost is rising in the one place your ad dashboards can't show it.
The reading to be most suspicious of is 0.0%. For a store paying anyone at all to help it sell, that's a tagging gap rather than a lean operation, and every profit figure below it on the page is flattered by the same amount.
How to improve it
| Lever | What you do | Expect | How long | Watch out for |
|---|---|---|---|---|
| Fast Tag what's already there | Go through Cost Settings and mark every genuinely marketing cost as Ad Spend | The number becomes real, and usually rises | Same week | True Ad Spend, True NCPA and every profit line move against you the day you do it. Nothing got worse — you were reading an incomplete number. |
| Fast Stop paying for what isn't producing | Review each tagged line against what it was hired to deliver, starting with the largest | The share falls in the month you cancel | 1 month | Some of that spend is building demand you'll only measure two quarters out. Cutting creators is the fastest saving and the slowest one to understand. |
| Slow Put the agency on a percentage | Swap flat retainers for a share of sales so the cost moves with the month | The ratio stops spiking in quiet months | 1 quarter | Strong months cost more, and a growing year can total well above what the retainer would have. You're buying stability, not savings. |
| Slow Grow the denominator | Add sales without adding retainers, creators or fees | Falls with every point of growth, with nothing cancelled | 1–2 quarters | Growth bought on the platforms improves this ratio while pushing MER the other way. The total marketing bill can rise while this number looks better. |
Every lever costs something somewhere. The last column is the one to read twice.
Read it with
This is one half of your real marketing bill. On its own it undercounts, and the platform number undercounts in the opposite direction.
True Ad Spend is platform spend plus these tagged costs, so this share is precisely the part MER leaves out. Read them together and you get the whole marketing bill as a share of sales; read either alone and you're steering on a fraction of it.
% Custom Expenses covers everything you enter, tagged or not. This one is the advertising slice of it, and the rest is overhead. The gap between them tells you whether your entered costs are mostly a growth investment or mostly the cost of keeping the lights on.
Common misreads
Far more likely nothing has been tagged. The figure is built entirely from entries you ticked as Ad Spend, so an untagged agency retainer sits in overhead instead and never reaches this column.
It doesn't. MER uses platform-reported spend only. These are separate costs you entered yourself, which is why the app carries True Ad Spend as a distinct figure that adds the two together.
Total Sales sit in the denominator. A fixed retainer against a slow month lifts this ratio with nobody spending an extra euro. Check the amount in euros beside it before going looking for a culprit.
Also called
Off-platform ad spend ratio · non-platform marketing cost share · tagged ad spend as a share of sales
See yoursYour tagged marketing costs as a share of sales, beside True Ad Spend, MER and True NCPA for the same period.
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