What is Contribution Margin?

Gross margin tells you whether your products are priced above what they cost you. Contribution margin tells you whether your orders actually make money once everything that comes with them is paid for - the goods, the box, the courier, the card fee and the ad that brought the customer in.

A store can look healthy at the gross margin line and still lose money on every order. Contribution margin is where that shows up.

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What Is Contribution Margin?

Contribution margin is net sales minus all variable costs - the costs that rise and fall with each order. For an online store that usually means cost of goods sold, shipping and packaging, payment fees and, in most cases, the marketing spent to win the sale. You can show it as an amount or as a percentage of net sales.

What is left is what each order "contributes" towards fixed costs - rent, software, salaries - and then profit. If it is negative, selling more makes things worse.

🧒 Explained simply You sell a cup of lemonade for $1. The lemons and sugar cost 30 cents, the cup costs 10 cents, and you paid your little brother 20 cents to hold up a sign that brought the customer over. That leaves 40 cents. Those 40 cents are your contribution - the money that pays for the table you bought and, after that, goes in your pocket.

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How to Calculate Contribution Margin

Contribution Margin = Net sales − Variable costs (COGS, shipping, fees, marketing)

To get the contribution margin ratio, divide by net sales:

Contribution Margin Ratio = Contribution margin ÷ Net sales × 100

Say a store has, for one month (illustrative round numbers):

• Net sales: $50,000
• Cost of goods sold: $22,000
• Shipping and packaging: $6,000
• Payment fees: $1,500
• Marketing spend: $10,000

Contribution margin = $50,000 − $22,000 − $6,000 − $1,500 − $10,000 = $10,500, or 21% of net sales.

The same store's gross margin is 56%. The gap between 56% and 21% is the cost of reaching customers and getting products to them.

A few variants are worth knowing:

• Before and after marketing. Some teams calculate contribution before marketing (sometimes called CM2) and after it (CM3). The version after marketing is the one that tells you whether growth pays for itself.
• Per order. Divide contribution by order count. It makes the cost of free shipping on small baskets very visible.
• Shipping charged vs paid. If customers pay for shipping, net what they paid against your carrier costs, consistently each month.

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Why Contribution Margin Matters

Contribution margin is the number that decides whether scaling is a good idea. A store with a healthy gross margin can still have orders that lose money once shipping, fees and ad spend are added, and those losses grow with every extra order.

It also sets two of the most important limits in an online store:

• Break-even ROAS. If your contribution before marketing is 40% of sales, every $1 of ad spend needs to bring in at least $2.50 of sales just to break even. Anything below that is buying revenue at a loss.
• Free-shipping threshold. Knowing what an order contributes before shipping tells you the basket size at which you can afford to cover delivery.

It also settles arguments about products: a lower-margin item that is light to ship can contribute more per order than a high-margin item that is expensive to ship.

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What Is a Good Contribution Margin?

There is no universal figure. Contribution margin depends on your category, your price points, how heavy your products are and how you acquire customers, so another store's number tells you very little about yours.

The minimum is simple: a positive, stable contribution margin per order after marketing. That is the floor for growth that pays for itself. Above that, watch the trend - by month, by product and by channel - and look for orders, products or campaigns that sit below zero.

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How to Improve Contribution Margin

1. Find the orders that lose money

Calculate contribution per order by product and basket size. Small single-item orders with free shipping are a common leak - raise the threshold, add a small-order fee or bundle the product.

2. Set your free-shipping threshold from the numbers

Set the threshold where an order above it can absorb the shipping cost and still contribute, rather than picking a round number by feel.

3. Cut ad spend that is below break-even ROAS

Work out break-even ROAS from your contribution before marketing, then compare each campaign against it. Campaigns that consistently sit below break-even need new targeting, a new offer or less budget.

4. Reduce packaging and fulfilment cost per order

Right-size boxes, review carrier rates every year and check whether a second carrier is cheaper for certain zones or weights. These savings land straight in contribution on every order.

5. Discount less and more selectively

Every discount comes off contribution in full. Target promotions at slow-moving products or lapsed customers instead of running store-wide codes. Bundles are often a better lever - they raise order value without lifting per-order costs at the same rate.

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How to Track Contribution Margin

Contribution margin pulls from several systems, so no single tool has every input. Chartsy for Ecommerce connects to your BigCommerce store with read-only access and syncs orders, products and customers every hour. From those it reports net sales, shipping and - where cost prices are recorded in your store - cost of goods sold and gross profit, by month, product and category.

Payment fees come from your payment provider, and marketing spend comes from your ad platforms. Combine those with the Chartsy figures to get contribution after fees and marketing. If cost prices are missing in your store, Chartsy can't fill them in, so recording them is the first step.

With ChartsyAI you can also ask for the order-based parts directly:

• "Show net sales and shipping by month for the last 12 months"
• "Show gross profit by product for last quarter"
• "Which categories had the highest gross profit this year?"

Try Chartsy for Ecommerce free for 14 days →

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