How to Set Your Free Shipping Threshold (Without Killing Margins)
Free shipping increases conversion rates and AOV — but set the threshold wrong and it eats your margin. Here's the math.
Jakob Sperber
Director
Strategy
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Free shipping is one of the highest-leverage conversion levers in ecommerce. It reduces cart abandonment, lifts average order value, and removes the single biggest source of checkout friction. But it's not free for you — someone pays for it, and if you set the threshold wrong, that someone is your margin.
The question isn't whether to offer free shipping. Most brands should. The question is at what threshold, and whether the maths actually works once you factor in product weight, shipping zones, and contribution margin.
Why Free Shipping Matters More Than You Think
Shipping costs are the number one reason customers abandon their cart. When you remove that friction, three things happen:
Conversion rate increases. Customers who see "free shipping" don't have to do the mental arithmetic of whether the total is still worth it.
Average order value increases. When you set a threshold, customers actively add items to qualify.
Perceived value improves. Free shipping reframes the transaction. The customer feels like they're getting a deal, even when the cost is baked into pricing.
But all three benefits are useless if the shipping cost you absorb wipes out the margin on the order.
The Formula: Set the Threshold 15–20% Above Your Current AOV
Take your current average order value and add 15–20%. That's your initial threshold. High enough that customers need to add something to qualify, low enough that it feels achievable.
Worked Example
Current AOV: $75
Average shipping cost: $9
Average product price: $25–$35
Current CM2 per order: $35
You set your free shipping threshold at $89 (~19% above AOV). A customer with $75 in their cart sees: "Spend $14 more for free shipping." They add a $25 item. Order is now $100. You absorb $9 in shipping but gain $12.50 in contribution margin on the extra product.
Net result: +$3.50 in margin, higher AOV, and a customer who converted instead of abandoning.
The Margin Check: Can You Actually Afford It?
What does absorbing average shipping cost do to your CM2? If you're not familiar with the contribution margin stack, read the full breakdown of CM1, CM2, and CM3 first.
If your average shipping cost is $9 and CM2 per order is $35, absorbing shipping drops CM2 to $26 — a 26% hit. If CM3 was already tight at $8 per order, absorbing $9 in shipping means you're losing money on every qualifying order where the customer didn't add extra items.
Run the numbers through your accounting framework before you announce anything.
When Free Shipping Destroys Margin
Low-AOV products. If average order is $30 and shipping is $9, you're giving up 30% of revenue.
Heavy or bulky products. Furniture, fitness equipment, bulk pet food — shipping costs scale with weight.
Regional AU shipping. Metro might cost $8. Alice Springs or rural Tasmania can hit $18–25.
Low-margin categories. Gross margin below 40% leaves very little room to absorb shipping.
When Free Shipping Is a No-Brainer
Lightweight, high-margin products. Skincare, cosmetics, jewellery, supplements. Under 500g with 65%+ margin.
Consumables and replenishables. Free shipping reduces friction on repeat purchases and improves cross-sell opportunities.
High-AOV categories. $150+ AOV means $9 shipping is 6% of revenue. Easy to absorb.
Subscription models. Bake shipping into the subscription price.
Conditional Free Shipping: The Smart Approach
Threshold-Based (Best for Most Brands)
Minimum order value. Display prominently: a progress bar in the cart showing "You're $14 away from free shipping" is one of the highest-ROI UX elements you can add.
Membership-Based
Free shipping as part of a loyalty or membership programme. Locks in repeat purchases and increases switching costs.
Product-Specific
Free shipping on high-margin products but not on low-margin or heavy items. Use it as a merchandising lever.
How Thresholds Affect AOV
Typical AOV lifts from a properly set threshold: 8–15%. On a $75 AOV, that's $6–11 per order. If your average shipping cost is $9, the AOV lift alone can cover most or all of the shipping expense — before conversion rate improvement.
Measuring Success
AOV lift. Compare before and after. Look for clusters of orders just above the threshold.
Shipping cost as % of revenue. Will go up, but should be offset by AOV lift.
Conversion rate. Track cart-to-purchase conversion specifically.
The ultimate metric: net CM2 per order after shipping. If it's higher than before, the strategy is working.
Common Mistakes
Threshold too low. If 70% of orders already exceed it, you've given away shipping without changing behaviour.
Threshold too high. If customers can't reach it by adding one item, they ignore it.
Ignoring AU shipping cost variation. Model blended costs across all zones, not just metro.
Not updating the threshold. AOV changes seasonally. Review quarterly.
Treating it as marketing, not finance. Start with unit economics, then use it as a conversion tool.
The Bottom Line
Free shipping works. Set the threshold 15–20% above current AOV. Check that absorbing shipping doesn't destroy your CM2. Make it easy for customers to add items to qualify. Track weekly. Adjust quarterly.
And if you haven't nailed your unit economics yet, do that first. Knowing your contribution margins at each level is the foundation that tells you whether free shipping is a growth lever or a margin trap.
