Check MarginOS’s starting assumptions
Quick Reference
Inputs
A rough blended acquisition cost and a rough gross margin. Neither is required, and both can be corrected later.
Outputs
Baseline acquisition and margin assumptions plus store-wide shipping and payment-processing defaults, all tracked as assumptions rather than measurements.
Outcomes
Leave setup knowing exactly which of your numbers rest on assumptions, and which two defaults are most likely to be wrong for your store.
The last step of Express Setup is headed Check our assumptions, and the wording is deliberate. MarginOS needs a few baseline numbers to show you a profit figure before your real costs have arrived, so it proposes sensible ones and asks you to confirm them. Both fields are optional and there is a Skip for now (use defaults) button — skipping is a legitimate choice, not a corner cut. The two fields behave differently when skipped, though, and the difference matters: the margin estimate falls back to a stated default, while acquisition cost does not — MarginOS will not invent a CAC.
Why MarginOS asks instead of guessing quietly
On day one MarginOS knows what you sold, because Shopify tells it. It does not yet know what any of it cost you. Without a baseline it could either show you nothing at all, or invent a number and present it as fact. It does neither: it asks for an assumption, uses it, and then tracks it as an assumption for as long as it lasts.
That distinction runs through the whole product. A figure resting on a store-wide baseline is graded differently from one resting on a real per-item cost, and you can always see which you are looking at — see the Defensible Profit Model and Data Trust levels.
Before you start
- This is step 3 of 3, so you will already have completed the brand questions and connected Shopify.
- Rough numbers are fine. An approximate figure you have sanity-checked beats a precise one you invented, and both beat leaving a metric blank.
- Nothing here is permanent. Every value on this screen is editable afterwards in your business settings.
How to review the assumptions
- Read the two fields at the top: Blended CAC (Optional) and Est. Gross Margin % (Optional). Fill in either, both, or neither.
- Read the Industry defaults applied for other metrics panel beneath them. You cannot edit these here — the panel exists so you know what is being assumed on your behalf.
- Either click Finish and go to dashboard to save what you entered, or Skip for now (use defaults) to accept every default as-is.
The two figures you can set
| Field | What it means | If you leave it blank |
|---|---|---|
| Blended CAC | Your target or current average cost to acquire one customer, across all channels. Entered in dollars. | Nothing is assumed. Your CAC reads N/A — along with the payback and efficiency metrics that divide by it — until either you set a figure or MarginOS can measure one from connected ad spend. You will be prompted to set one. |
| Est. Gross Margin % | Roughly what share of a sale you keep after the product itself. Entering 60 tells MarginOS to assume product cost is 40% of price until real costs arrive. |
MarginOS assumes 60%, as the field’s own hint says. |
The defaults applied for you
The panel lists what MarginOS assumes for everything else. At the time of writing it covers:
- Shipping cost — $10.00 per order.
- Payment processing — 2.9% + $0.30, the common card-processing shape.
- Payback target — a starting window for CAC Payback. Confirm the value that actually applies in Business Config → Business Profile → Marketing, which is where that metric reads it from.
- Hero SKU threshold — how many units in 30 days make a product a Hero. This one is derived from the revenue band you gave in step 1, so the number shown is specific to your store’s size.
Shipping and payment processing are the two worth a second look. A brand shipping heavy goods, or one on a payment plan well away from standard card rates, will find $10.00 and 2.9% materially wrong — and because they apply to every order, an error there moves every margin figure you look at. Correct them in your store-wide cost defaults.
What happens to these numbers afterwards
They are a floor, not a ceiling. As real evidence arrives it takes precedence: actual per-item costs replace the margin assumption for the products they cover, and once an ad platform is connected MarginOS computes acquisition cost from measured spend rather than the figure you typed — see how MarginOS resolves blended CAC.
So expect your numbers to move as you connect more sources, and expect them to move down on the margin side. A store with no cost data looks more profitable than it is, because there is very little to subtract yet. That is the expected shape of a first week, not a fault.
Common questions
Should I just skip this step?
You can, and the product is designed to let you. But the two fields take about thirty seconds, and for acquisition cost the trade-off is sharper than it looks: skip it and your CAC — plus the payback and efficiency metrics measured against it — read N/A until you connect an ad account. MarginOS will not fill that gap with a guess. If you know your blended CAC roughly, type it.
What if my gross margin varies a lot across products?
Give the blended figure across your catalogue; that is what the field is for. Per-product accuracy comes from real costs, not from a more agonised store-wide average. If your range is genuinely wide, that is an argument for prioritising real cost data, not for perfecting this box.
Will these assumptions overwrite my real costs later?
No — the precedence runs the other way. A baseline only ever applies where nothing more exact exists, and it steps aside the moment something does. That is the entire point of grading costs by how well evidenced they are.
Where do I change these after setup?
In your business settings. The cost-side values live with your store-wide COGS, shipping and pick-pack defaults, and the acquisition and payback values live under Business Profile → Marketing. The wizard is a fast first pass, not a one-time commitment.
Why does my margin look suspiciously good right after setup?
Because the costs that would bring it down have not arrived yet. Revenue lands immediately from Shopify; product costs, fulfilment and ad spend arrive as you connect their sources. Treat the first days as a shape rather than a number, and watch the accuracy grading climb as you supply evidence.
Why does MarginOS show N/A for some metrics instead of using a default?
Because a default is only honest where it is genuinely a reasonable stand-in. For metrics that depend on data MarginOS simply does not have — acquisition cost before any ad account is connected, for instance — inventing a plausible figure would be worse than admitting the gap. See why MarginOS shows N/A.
Related
- Set up MarginOS: the 3-step Express Setup — the wizard this step belongs to.
- Set your store-wide COGS, shipping and pick-pack fallbacks — where to refine these afterwards.
- The Defensible Profit Model — how assumptions and evidence are told apart.
- How MarginOS resolves blended CAC — what replaces the figure you typed.
- Getting Started — the rest of onboarding.
About the author
Founder of MarginOS, a Profit & Inventory OS for Shopify DTC brands who live and die by margin. Previously 11 years at Google across Ads and Global Business Operations, building large-scale systems. Now focused on giving DTC operators true profit by product, channel, and customer after COGS, 3PL, shipping, returns, and fees, and on showing exactly how much to trust every number behind those decisions.
Read Aron's story