Free shipping sounds like a growth lever. Sometimes it is. But without the right math behind it, you're subsidizing orders your margins can't afford.
Here's how to actually think through the decision.
Why Free Shipping Works (When It Works)
The data is real: Baymard Institute found that unexpected shipping costs are the #1 reason for cart abandonment, cited by 48% of shoppers. Offering free shipping removes friction at the most critical point in the purchase journey.
For brands with high average order values (AOV) and healthy margins — think a $90 skincare kit with 65% gross margin — absorbing a $7 shipping cost is a no-brainer. The conversion lift more than pays for itself.
But most brands don't stop to verify those conditions before flipping the switch.
The Margin Math You Need to Run First
Start here. Before offering free shipping on anything, calculate your fulfillment cost as a percentage of AOV.
If your AOV is $35 and your all-in shipping cost (carrier rate + fulfillment fee + packaging) is $8, that's nearly 23% of every order going to get the product to the door. On a 50% gross margin product, you're left with about $9.50 in contribution margin before any advertising, returns, or overhead.
Free shipping in that scenario doesn't just compress margin — it can make individual orders unprofitable after CAC.
The math changes completely at higher AOVs. The same $8 shipping cost on a $90 order is under 9% of revenue. That's a very different trade-off.
The Free Shipping Threshold Strategy
The cleanest way to offer free shipping without bleeding margin is the order minimum threshold — and most DTC brands underuse it.
The approach: set your free shipping threshold 20-30% above your current AOV. If your AOV is $48, set the threshold at $60. You'll convert a meaningful portion of your customer base to spend up, and you'll protect margin on the orders that don't.
Bonus: threshold-based free shipping tends to increase AOV across the board, not just for the customers who hit it. The psychology of "you're $12 away from free shipping" drives upsells and bundle purchases without you having to engineer a complex promotion.
This is one of the highest-leverage, lowest-effort revenue tactics available to most Shopify brands — and it's criminally underused.
Where Brands Get This Wrong
The most common mistake: blanket free shipping applied at launch because a competitor offers it, without ever modeling the margin impact at scale.
A brand doing $100K/month in revenue shipping 1,200 orders might be absorbing $9,600 in shipping costs. That's a real number. At $500K/month, it's nearly $50K. If that wasn't in the original pricing model, it shows up as a profitability problem that's hard to reverse without damaging customer expectations.
The second mistake: not accounting for what fulfillment actually costs. Shipping isn't just the carrier label. It's the pick and pack labor, the packaging materials, the dimensional weight surcharges, and any special handling. If your 3PL isn't giving you full visibility into those line items, you're modeling with incomplete data.
When Free Shipping Absolutely Makes Sense
There are scenarios where free shipping should be the default, no hesitation:
- High-margin consumables or replenishment products where LTV is the metric that matters, not single-order margin
- Subscription boxes where the acquisition cost is spread across 6+ shipments and retention is the lever
- Influencer or launch drops where conversion rate and social proof outweigh short-term margin
- Loyalty or VIP tiers where free shipping is a retention tool, not a blanket discount
In each of these cases, the unit economics support it — but only if you've done the work to confirm that.
The Takeaway
Free shipping isn't a marketing decision. It's a unit economics decision that happens to affect marketing.
Run the math at your current AOV. Model what happens at a threshold 25% above it. Know your all-in fulfillment cost per order — not just the carrier rate. Then decide.
If you don't have clear visibility into what each order actually costs to fulfill, that's the first problem to solve — because you can't price a shipping policy around numbers you don't have.