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Free Shipping Threshold Optimizer

Set the threshold too low and you bleed margin. Too high and customers churn at checkout. This calculator finds the math-optimal line for your AOV and margin — and estimates the AOV lift you'll see at that threshold.

[ Step 1 ]

Your Numbers

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%
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[ Step 2 ]

Your Optimal Line

Math-optimal threshold—
Psychologically rounded—
Lift over current AOV—
Margin protected—

[ The Next Step ]

Free shipping is one CRO lever. There are seven more.

The full LeakAudit finds every conversion lever across product page, trust, mobile, copy, SEO, retention, app bloat, and speed.

Find them all →

Why your free shipping threshold matters more than you think

Surprise shipping costs are the #1 reason for cart abandonment in every Baymard Institute study. But "free shipping for everyone" usually means subsidizing customers who would've paid full freight anyway — straight margin off the top. The right answer is a threshold: a number that nudges the average order up far enough to cover the shipping cost, while still feeling generous.

The 30% rule (and why it's a starting point, not a verdict)

Industry rule of thumb: free shipping kicks in at roughly 30% above current AOV. If your AOV is $65, a $85 threshold is the textbook answer. The reason it works: customers add one more item to clear the bar (psychology calls this the "free-shipping nudge"), and the margin on that extra item more than covers your shipping subsidy.

The 30% rule is a starting point. The actual optimal threshold depends on your gross margin and your shipping cost. This calculator does the math: it sets the threshold high enough that the additional margin from the AOV lift fully covers the shipping you'll eat. Below that line, you lose money on every "free shipping" order.

When NOT to offer free shipping

A/B test before you commit

The threshold this calculator gives you is mathematically defensible — but real merchant data sometimes surprises. Before you commit, test two thresholds against each other for two weeks. The winner usually shows up by week one. If you have an A/B testing app installed, it's a 30-minute setup. If not, run it as alternating weeks and compare the AOV column in Shopify analytics.

Once you've nailed the threshold, run the full LeakAudit to find the rest of your conversion levers — most stores have eight stacked leaks, and free shipping is rarely the biggest.

Threshold FAQ

Five quick answers about the math.

Where does the 30% rule come from?

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It's a heuristic from CRO practitioners — set the free-shipping threshold roughly 30% above your current AOV and it nudges customers to add one more item without feeling extortionate. The exact number depends on your margin and shipping cost; the 30% is a floor, this calculator computes the actual math-optimal number.

Should I A/B test the threshold?

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Yes, especially if your monthly orders are over a few hundred. Test two thresholds (the calculator's recommendation vs. the rule-of-thumb 30% line) for two weeks each. Watch AOV and conversion rate — the right answer is the one that lifts AOV without dropping conversion meaningfully. If you have an A/B testing app installed, this is a 30-minute setup.

My margin is low — should I offer free shipping at all?

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If your gross margin is under 30%, the math usually doesn't work. Offer a flat shipping rate ($5 or $7) instead — buyers prefer predictable over deceptively-priced. If margin is 30–50%, free shipping above a threshold is usually right. Above 50% margin, you have flexibility to be more generous.

When does free shipping for everyone make sense?

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Three cases. (1) Your AOV is naturally high enough that shipping is a small percentage. (2) You sell digital or fulfilled-by-Amazon products where shipping cost is near zero. (3) You're in a category where everyone offers free shipping (apparel, beauty) and not offering it costs you more in conversion than you save in margin. Otherwise, threshold.

How often should I re-check this?

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Whenever your AOV, margin, or shipping cost changes meaningfully — usually once a quarter is enough. Carrier rate increases (USPS, UPS, FedEx all raise rates annually) are the most common trigger. If you raise prices, your AOV moves and your threshold moves with it.

Threshold is one lever.
The audit is the rest.

Find every lever — across all eight ecommerce categories.

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