Bundle Metrics: Attach Rate, AOV and Profit per Order Explained

Six numbers tell you whether a bundle offer is working: attach rate, bundle share of orders, units per order, average order value, discount cost and profit per order. The first four show whether shoppers are taking the offer. The last two show whether you are better off because they did. This guide defines each one with its formula, works a single example through all six, and sets out a short monthly review and a check for cannibalisation.

Which bundle metrics matter?

The ones that connect uptake to profit. An offer can score well on every uptake measure and still lose money, so the six are read together.

The example used throughout: say a store takes 1,000 orders in a month, containing 1,600 units, with $52,000 in sales after discounts.

How do you calculate attach rate and bundle share?

Attach rate is the share of orders for a main product that also include its add-on or companion.

Attach rate = orders containing the main product and the add-on ÷ orders containing the main product.

Say the main product appears in 600 of the month's orders, and 120 of those include the add-on. Attach rate is 120 ÷ 600, or 20 percent. Always state which pair the figure is for; a store-wide attach rate averages good pairings with bad ones and hides both. Choosing pairings that earn a high rate is covered in how to choose frequently bought together products.

Bundle share of orders is the proportion of all orders that used any bundle offer.

Bundle share = orders that include a bundle offer ÷ total orders.

If 250 of the 1,000 orders used an offer, bundle share is 25 percent.

How do units per order and AOV fit together?

They are two views of order size, and the difference between them is the discount.

Units per order = total units sold ÷ total orders. In the example, 1,600 ÷ 1,000 = 1.6.

Average order value (AOV) = total sales after discounts ÷ total orders. In the example, $52,000 ÷ 1,000 = $52.

Read them as a pair. If units per order rises and AOV rises by less, the gap is what you gave away in discount to get the extra units.

AOV counts sales, not profit, and a deep enough discount will raise it every time.

What is discount cost?

The money given up to make the offers work.

Discount cost = the sum of all bundle discounts applied in the period.

Express it two ways:

• Per bundle order = discount cost ÷ orders that include a bundle offer. If the month's bundle discounts total $3,000 across 250 orders, that is $12 per bundle order.
• As a share of bundle sales = discount cost ÷ bundle sales before discount. This is your effective discount rate, and it rises as more shoppers choose the top tier.

Count only bundle discounts here. Keep welcome codes and sale discounts in their own lines, or you will blame the bundle for a cost it did not cause.

How do you calculate profit per order?

Profit per order = (sales after discounts − cost of goods − shipping cost − payment fees) ÷ total orders.

In the example, say cost of goods is $20,800, shipping costs you $6,000 and payment fees are $1,600. Profit is $52,000 − $28,400 = $23,600, or $23.60 per order.

Then split it, because the store-wide average hides the answer you want:

• profit per order on orders with a bundle offer;
• profit per order on orders without one.

If bundle orders earn more per order, the offers are doing their job. If they earn less, the larger baskets are being bought with margin.

What does a simple monthly review look like?

Thirty minutes, the same six numbers, compared with the previous month.

1. Record the six metrics for the store.
2. Record attach rate, discount cost and profit per order for each active offer.
3. Mark any offer whose profit per order is below that of orders without it.
4. Mark any offer with a very low uptake. It is taking up page space.
5. Run the cannibalisation check below on your largest offer.
6. Decide one change for the coming month, and only one, so next month's numbers can be read.

Use the same data source each month. Shopify's reports give orders, units and sales. Marka Bundles & Upsells includes standard reporting on the Free plan, with advanced analytics and native funnels from the Growth plan. For profit after costs and fees across the whole store, an analytics tool such as Marka Metrics saves rebuilding the sum in a spreadsheet.

How do you check for cannibalisation?

Compare how many customers bought the bundle quantity at full price before the offer existed with how many buy it at a discount now.

Say that before a three-for-less offer, 8 in every 100 orders for the product already contained three or more units, at full price. After the offer, 20 in every 100 do. Twelve of those are new behaviour. The other 8 would have bought three anyway, and are now receiving a discount for doing what they did before. Their discount is pure cost and should be subtracted from the offer's gain.

Two further checks:

• Full-price sales of the bundled items. If a fixed bundle's sales rise by the amount the individual products fall, you have moved sales, not added them.
• Reorder timing. A customer who buys three months' supply will reorder later. Compare sales per customer over a longer window before calling the offer a success.

Cannibalisation never falls to zero. The aim is an offer whose new sales outweigh the discount handed to people who needed no persuading. If the check fails, reduce the discount or move the tier up, using the method in how much discount a bundle should have.

A short checklist

1. Track attach rate per pairing, not store-wide.
2. Read units per order and AOV together.
3. Keep bundle discount cost separate from other discounts.
4. Split profit per order into orders with and without an offer.
5. Review monthly from the same data source.
6. Check each large offer for cannibalisation before scaling it.

These definitions extend the measurement section of our guide to Shopify bundle types. For bundle offers with reporting included on every plan, see Marka Bundles & Upsells.