How to calculate a free-shipping threshold that protects profit

Choose a free-shipping threshold by comparing the contribution from actual baskets before and after the offer. Include the shipping revenue you give up, the cost of the extra products, and any additional picking, packaging or delivery charges. Then test whether the offer increases total contribution from comparable traffic.

Average order value is a useful starting point. It cannot tell you whether the extra item pays for free shipping. A $15 add-on might fit in the same mailer, or it might force the order into a larger carton and a higher shipping charge. Those are different offers economically, even when checkout shows the same total.

Build the calculation around money you keep

Use this working definition:

Order contribution = product revenue after discounts + shipping revenue collected − product cost − payment fees − fulfillment − packaging − carrier charges − expected return losses.

This is contribution before advertising and fixed overhead, not net profit. If acquisition costs differ between test groups, include that difference when deciding whether to keep the offer.

Keep sales tax outside the revenue comparison. Enter the actual payment fee, including any fee attributable to tax, if your processor charges it. Use a consistent treatment of recoverable taxes on costs.

For expected return losses, estimate the average net loss per order: refunds, return handling and other unrecovered costs, after allowing for recoverable inventory value. Avoid subtracting refunds twice if your revenue input is already net of returns. Until a test’s returns mature, use a reserve based on comparable products and customers, then replace the estimate with actual results.

A $75 threshold: work through both baskets

Suppose a merchant is considering free standard shipping at $75. Its typical eligible basket is $60 and currently pays $6 shipping. The customer can reach $75 by adding another product.

The following figures are invented for illustration, in Canadian dollars. They are not carrier, payment processor or 247 Fulfillment rates. Tax is excluded from this simplified example; payment fees are assumed to be 3% of the amount collected plus $0.30.

The larger order contributes $1.73 more. It produces $15 of additional product revenue, but the merchant gives up $6 of shipping revenue and incurs $7.27 of additional costs.

Copy this table for several realistic baskets. Use the products shoppers are likely to add, their actual margins, and the packaging those combinations require. A category-wide average product margin can disguise a weak add-on.

Check the order that changes the answer

Now suppose the extra item requires a carton costing $0.75 more and raises the carrier charge by $4. The $75 basket contributes $17.70 instead of $22.45. That is $3.02 less than the original $60 order.

Before promoting an add-on beside a free-shipping progress bar, pack the combination and price the parcel. Our dimensional weight audit explains which measurements to check.

Also model orders shipping in two parcels. A threshold that works when everything is available in one building can fail when inventory forces separate shipments. Use the split-shipment cost framework to include that exposure.

Review three groups separately: baskets just below the proposed threshold, baskets already above it, and expensive destinations. Customers already spending $75 may receive a subsidy without adding anything. That cost belongs in the test even though their order value does not change.

Choose a candidate shoppers can realistically reach

Start with your recent distribution of eligible order values, rather than applying a universal percentage above average order value. Remove unusual wholesale orders or other transactions outside the offer’s intended audience.

For each candidate threshold, answer four questions:

1. How many existing orders would immediately receive free shipping?
2. Which products would shoppers plausibly add to qualify?
3. What happens to parcel size, weight and item-picking charges?
4. Which destinations or services make the offer uneconomic?

A $79 threshold has little meaning if the most natural add-on takes a $60 basket directly to $90. Model the $90 basket. Avoid assuming customers can add an exact dollar amount.

Give the offer clear boundaries, such as eligible destinations and standard delivery. Make those terms visible beside the offer so customers can understand it before checkout.

Test contribution from comparable traffic

Set the decision metric before launching: total order contribution divided by eligible sessions, with a consistent definition of an eligible session. Track conversion, contribution per order, shipping subsidy, units per order and returns alongside it.

In a deliberately simplified example, 1,000 eligible sessions producing 40 orders at $20.72 contribution generate $828.80. Another 1,000 producing 42 orders at $22.45 generate $942.90. That arithmetic illustrates the metric; it is not evidence that a small observed difference will repeat.

Use a randomized test where practical. Keep competing promotions, traffic sources and delivery promises comparable, and allow enough orders and return history to judge the result. If you can only compare periods, record changes in traffic mix, seasonality and discounts; they limit what you can attribute to the threshold.

Do not declare success from a higher average order value alone. Fewer buyers, heavier parcels or more returns can erase that gain.

Make the checkout match the promise

Shopify supports minimum purchase requirements for free-shipping discounts. Its free-shipping discount guidance says product prices count toward the minimum, taxes do not, and eligible combined discounts reduce the product value used for qualification. Check the combinations you actually allow.

Test a basket just below, exactly at and just above your threshold, with and without an eligible product discount. Include each relevant shipping profile and destination. Shopify’s shipping-rate guidance also cautions that conditional rate tiers need full coverage; a gap can leave a customer without a shipping rate.

Bring your candidate baskets, packed dimensions and destination mix to a fulfillment planning conversation. Those details make it possible to discuss a shipping offer around the orders your business actually sends.