Free shipping
Worst-zone free shipping cost check.
Enter the item, the packed parcel and your zone mix. See postage and margin at every USPS zone, the worst zone you ship to, and the price that keeps your target margin there.
Item, parcel and zone mix
Result
What this page answers
Free shipping is not one cost. It is the postage to every zone you sell to, folded into one price, so the customer in zone 1 and the customer in zone 8 pay the same and cost you different amounts. A margin worked out on the average order hides the zone where you lose money.
This page prices your packed parcel at every USPS zone and then shows the margin, the break-even price and the price that holds your target margin at each one. It is a different question from a free-shipping threshold: here the shipping is always free and the variable is distance.
How it is calculated
Postage per zone is the USPS Ground Advantage retail price from the Notice 123 parcel table for the packed weight (or its dimensional weight when the parcel is over 1 cubic foot), plus any length, cube or characteristic fee.
Left per order = item price - platform fee percent of the price - fixed fee - product cost - other cost - postage. The price that holds a target margin m at a given postage solves price x (1 - fee% - m) = product cost + other cost + fixed fee + postage. The worst zone is the highest-postage zone with a share above zero; the average uses your zone mix, normalised to 100%.
Worked example: a $39.99 item
A $39.99 item costs $14.00 to buy and $1.20 to pack, with a 15% platform fee plus $0.30 per order. It ships in a 10 x 8 x 4 in, 2 lb parcel. Target margin 20%. The mix is a placeholder: 10% each to zones 1, 2, 7 and 8 and 15% each to zones 3 to 6.
Postage at 2 lb runs from $11.30 in zone 1 to $19.80 in zone 8, a spread of $8.50. The weighted average is $14.57, which leaves $3.93 per order, a 9.82% margin. In zone 8 the order loses $1.31.
To hold a 20% margin on the average order the price would be $46.25; to hold it in zone 8 it would be $54.31. Break-even in zone 8 is $41.53, so at $39.99 the item is under water there before any return or ad cost.
Where this stops
Postage is the Ground Advantage retail list price. Commercial or cubic prices are lower, so if you have a rate card, use it to judge how far the real spread is from this one. The zone mix is yours to supply; this page has no data on where sellers ship and the default shares are placeholders. Zones are assigned by USPS to an origin and destination ZIP pair and are not looked up here. Returns, ad spend, taxes and carrier surcharges are not modelled, except through the other-cost field.
Sources
- USPS Notice 123 Price List, effective October 4, 2026: USPS Ground Advantage Retail parcels table and its notes (retrieved 2026-10-26)
- USPS Domestic Mail Manual 133, section 1.4 Dimensional Weight Price for Low-Density Parcels; steps marked [7-12-26] (retrieved 2026-10-26)
Carriers revise prices and rules during the year. Confirm against the live documents before relying on a figure for a contract or a dispute. This is a calculator, not a carrier quote.
Common mix-ups
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Often assumedPostage for a given parcel is about the same wherever it is going.
What the source saysIn Notice 123 a 3 pound Ground Advantage retail parcel costs $11.80 to zone 1 and $23.15 to zone 8, so one flat free-shipping allowance is too high for near customers and too low for far ones. [1]
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Often assumedDistance only matters for heavy parcels; light ones cost the same in every zone.
What the source saysThe 4 ounce Ground Advantage retail row in Notice 123 runs from $8.40 in zone 1 to $10.20 in zone 8, so even the lightest parcels carry a zone spread. [1]
Checked against these sources on .
FAQ
What is the worst zone for free shipping?
It is the highest-postage zone you actually ship to. In Notice 123, postage rises with the zone for every weight, so it is usually the farthest zone with orders in your mix. The tool finds it from your shares.
How do I build free shipping into the price?
Add the postage you expect to pay to your costs and solve for the price that leaves your target margin after platform fees. This page does it for the average postage of your zone mix and for the worst zone, so you can see the gap.
Should I price for the average zone or the worst zone?
That is a business choice, and the page shows both numbers. Pricing for the average only works if your real zone mix matches your assumed one; pricing for the worst zone protects the margin everywhere but raises the price for near customers.
Where do I find my zone?
USPS assigns a zone to each origin and destination ZIP code pair. Look yours up in the USPS Domestic Zone Chart; this tool does not look zones up for you.