“Our margin is 35%” — a phrase that usually prompts me to ask one question: 35% of what exactly? On marketplaces, you can calculate margin in dozens of ways — and 7 of them will be pleasantly misleading. Therefore, in this article, we will cover:
- how to correctly calculate margin for managing sales on Mercado Libre;
- the different types of margin and how they differ;
- common calculation errors that cause profits to leak, even when turnover is growing;
- a simple margin calculation template by SKU.
What is Margin in Simple Terms
Margin is the portion of money that remains after expenses, expressed in money or percentage.
There are two popular concepts:
- Margin in money: how much is left from one sale.
- Margin in percentage: how much is left from revenue.
The key is to always clarify which expenses you have already deducted; otherwise, comparing numbers is meaningless.
Margin Formula: Basic Version
If you want to calculate “honestly” for marketplaces, it is most useful to start with margin per unit (per piece):
Margin ($/unit) = Selling Price (actual) − Commission − Logistics/storage − Cost Price − Packaging/labeling
And margin in percentage:
Margin (%) = Margin ($) / Selling Price (actual) × 100%
“Selling Price (actual)” is the price at which it was actually sold, after discounts, promotions, and platform mechanisms. This is critical.
Types of Margins: 4 Levels to Distinguish
1) Gross Margin
Calculated approximately as follows:
Gross Margin = (Revenue − Cost Price) / Revenue
The problem: on marketplaces, gross margin does not account for commission, logistics, storage, advertising, and returns. Therefore, it often looks great and does not save from losses.
2) Margin After Marketplace (Contribution Margin)
This is the “managerial” margin that should be used for pricing and assortment decisions:
Margin After Marketplace = Actual Price − Commission − Logistics/storage − Cost Price − Packaging
3) Margin After Advertising
If you are actively growing through advertising, add:
Margin After Advertising = Margin After Marketplace − Advertising Costs per unit
Advertising costs can be conveniently linked through DRR and calculated at the SKU level. → See the main guide: Profit and Margin on Marketplaces and about advertising: DRR and Advertising: How to Calculate and Manage
4) Net Margin
This is when you have also deducted taxes and operational business expenses. It is useful for daily SKU management, but calculating it is more complex and slower.
How to Calculate Margin Correctly: 15-Minute Algorithm
- Choose a period: week/month (for stability)
- Take the actual selling price (after discounts)
- Account for commission ($ or %)
- Add logistics/storage (on average per unit)
- Add cost price and packaging/labeling
- If necessary — add advertising ($/unit) and losses from returns
- Get Margin ($/unit) and (%)
- Do this at least for the top 20 SKUs by turnover/expenses — and you will immediately see “who feeds, who pulls down”.
Common Mistakes in Margin Calculation (and How to Fix Them)
Mistake 1. Calculating Margin from “Shelf Price” instead of Actual Selling Price
The most destructive. On marketplaces, there are discounts, promotions, and mechanics that cause “shelf” and “actual” to differ significantly.
How to Fix: calculate from the actual selling price for the period.
Mistake 2. Not Accounting for Marketplace Commission
Sometimes people calculate “margin = price − cost price” and are pleased. Then it turns out that the commission and services ate up half.
How to Fix: subtract commission as a mandatory element of the model.
Mistake 3. Ignoring Logistics and Storage (especially for bulky goods)
Logistics may be small in percentage but large in money, and can kill low-margin SKUs.
How to Fix: add average logistics/storage per unit to the calculation.
Mistake 4. Not Accounting for Packaging/Labeling/Consumables
These small things “eat up” margin, especially on cheap products.
How to Fix: fixed expense per unit (at least approximately).
Mistake 5. Not Accounting for Returns and Losses from Returns
A return is not just a “minus sale.” It involves:
- reverse logistics,
- sometimes damage/defects,
- frozen money,
- drop in rating and future conversion.
How to Fix: at least roughly add “losses from returns” ($/unit) = return rate × estimated losses.
Mistake 6. Confusing Margin and Markup
Markup is usually calculated from cost price:
(Price − Cost Price) / Cost Price
Margin — from price (revenue):
(Price − Cost Price) / Price
These numbers are always different. Sellers often refer to markup as margin — and build plans on sand.
How to Fix: always label the formula in reports.
Mistake 7. Not Linking Advertising to Margin
You can scale sales through advertising and not see that you are selling at a loss due to DRR.
How to Fix: add a level of “margin after advertising” for advertised SKUs. → Useful: DRR and Advertising: How to Calculate and Manage
Mistake 8. Calculating “Average Store Margin” and Not Seeing Loss-Making SKUs
The average margin may be normal while one SKU “eats up” everything.
How to Fix: calculate margin by SKU and rank:
- by turnover
- by advertising expenses
- by profit in money
Mistake 9. Calculating Margin Without Accounting for Changes in Conditions (commission/logistics/promotions)
Today the conditions are one way, tomorrow another — and the model hasn’t updated. You think you are selling profitably, but the platform has already changed the rules of the game.
How to Fix: weekly check “what has changed” + recalculation for top-SKUs.
Mistake 10. Relying on “Ideal Cost Price” Instead of Actual
The purchase price has increased, the exchange rate has changed, defects have increased — but the model has the old cost price.
How to Fix: regularly update the cost price (at least once a month).
Margin Calculation Template by SKU (Example)
Suppose:
- Selling Price (actual): $1,000
- Commission: $150
- Logistics+storage: $90
- Cost Price: $520
- Packaging/labeling: $20
**Margin ($) = 1,000 − 150 − 90 − 520 − 20 = $220 ** Margin (%) = 220 / 1,000 × 100% = 22%
If we add advertising $120/unit: Margin After Advertising = 220 − 120 = $100 (10%)
Mini-Checklist: Margin is Calculated Correctly if…
- you use the actual selling price, not the shelf price
- the model includes commission and logistics
- there is packaging/labeling
- advertising is accounted for at least for advertised SKUs
- returns are not ignored
- margin is calculated by SKU, not just “average for the store”