Your shipping cost per order is the postage for your package's billable weight to each customer's zone, plus any surcharges that apply, plus the box and filler. The useful number isn't one rate. It's the average across the places your orders actually go, and that average is usually higher than the rate to the nearest big city.
Here's how to work it out for your own product, with one example carried all the way through: a product that weighs 2 lb packed, in a 12 × 10 × 6 inch box, shipped from Austin, Texas.
Step 1: Work out the billable weight
Carriers charge for whichever is greater: the actual weight on the scale or the dimensional (DIM) weight, which stands in for the space the box takes up on the truck. So start with the packed order, not the product.
- Weigh the packed box with the product, filler and packing slip inside.
- Measure the box and round each side up to the next whole inch.
- Multiply length × width × height, then divide by the carrier's divisor.
The divisors and thresholds differ by carrier:
- USPS uses DIM weight only for parcels over one cubic foot (1,728 cubic inches). Above that, it divides by 139 and rounds up to the next whole pound.
- UPS divides by 139 at its Daily Rates and 166 at Retail Rates, and says DIM weight may apply to any of its package services. It has no one-cubic-foot cutoff like USPS's.
- FedEx divides by 139 for U.S. shipments.
In the example, the box is 12 × 10 × 6 = 720 cubic inches. That's under a cubic foot, so USPS bills the actual 2 lb. FedEx, and UPS at its Daily Rates, divide 720 by 139, get 5.18 and round up to 6 lb: three times the billable weight for the same box. At UPS Retail Rates, 720 ÷ 166 is 4.34, which rounds up to 5 lb. If the product fits a 10 × 8 × 4 box, FedEx and UPS Daily Rates drop to 3 lb.
Our free dimensional weight calculator runs this for all three carriers at once, so you can check the billable weight of every box size you use before you price anything.
Step 2: Find the zones your orders go to
Ground postage rises with distance, which carriers measure in zones. USPS measures between the first three digits of the sending and receiving ZIP codes, starting at Zone 1 for local mail. The higher the zone, the higher the price.
From Austin, Houston and San Antonio are Zone 2, Dallas is Zone 3, Oklahoma City is Zone 4, Denver, Chicago, Atlanta and Phoenix are Zone 5, Los Angeles and Miami are Zone 6, and New York, Boston and Seattle are Zone 7. You can look up the USPS zone between your ZIP and any other with our zone map.
Then pull your last few months of orders, group them by state or region, and note what share goes where. That mix matters more than any single rate. UPS and FedEx publish their own zone charts, so check those in your shipping app if you plan to use them.
Step 3: Price the package in each zone
Look up the rate for your billable weight in each zone you ship to. Buying labels online is cheaper than paying at the Post Office counter: USPS says shippers using its Click-N-Ship tool get lower commercial rates on many services, and shipping apps typically show commercial prices too.
For the example's 2 lb package on USPS Ground Advantage:
Zone from Austin | Post Office (retail) | Online (commercial) |
|---|---|---|
Zone 2 (Houston) | $12.00 | $8.48 |
Zone 3 (Dallas) | $12.70 | $8.66 |
Zone 5 (Chicago, Denver) | $14.85 | $10.50 |
Zone 6 (Los Angeles, Miami) | $15.85 | $12.13 |
Zone 7 (New York, Seattle) | $17.20 | $12.55 |
These prices come from the USPS price list effective October 4, 2026, which includes a temporary holiday increase that runs until January 17, 2027. Check the current list before you lock in a price.
For FedEx or UPS Daily Rates, price the 6 lb billable weight, not 2 lb (5 lb at UPS Retail Rates), in your shipping app or carrier account. What you pay there depends on your account and any discounts, so use your own quotes rather than a published average.
Step 4: Average it across your zone mix
Say 20% of your orders stay in Texas (call it Zone 3), 40% go to the middle of the country (Zone 5), and the other 40% split evenly between Zones 6 and 7. At online prices the example works out to:
(0.2 × $8.66) + (0.4 × $10.50) + (0.2 × $12.13) + (0.2 × $12.55) = about $10.87 per order
At Post Office prices, the same mix comes to about $15.09. If you priced shipping from the Dallas rate alone, you'd be about $2.20 short on the average order. Your own mix will be different, which is why it's worth pulling from your actual orders.
Step 5: Add the surcharges that apply
Base postage isn't always the whole bill.
- USPS adds nonstandard fees for awkward sizes. On Ground Advantage, a parcel longer than 22 inches and up to 30 inches adds $4.50, one longer than 30 inches adds $10.00 instead, and one bigger than 2 cubic feet adds $21.00. The Ground Advantage price list has no residential or fuel surcharge.
- FedEx prices some of these separately from the base rate. Its 2026 Service Guide adds a $6.45 residential surcharge to each Home Delivery package, and its fuel surcharge for Ground and Home Delivery is a percentage tied to the weekly diesel price. Negotiated rates can change these, so read the surcharge lines on your own invoices.
If you ship with UPS, read the surcharge section of its current rate guide the same way. The example box is under 22 inches on every side, so on USPS it adds nothing. On FedEx Home Delivery, the residential surcharge adds $6.45 to every order going to a house unless your account discounts it.
Step 6: Add packaging and packing time
The box, filler, tape, packing slip and label belong in the per-order cost, and so does the time it takes to pack. Work out your box and filler cost per order from your last supply invoice, then add your packing minutes at whatever an hour of your time is worth.
For the example, that's about $10.87 in postage at USPS online prices, plus packaging, plus packing time. That total is your real shipping cost per order.
Deciding what to charge customers
With a blended average in hand, you can choose how shipping shows up at checkout:
- Calculated rates pass each customer's actual postage on to them. They're accurate, but your farthest customers see your highest prices.
- A flat rate charges everyone the same. Set it near your blended average (plus packaging if you want to recover it), and near and far orders balance out.
- Free shipping over a threshold builds the cost into larger orders. Set the threshold where your margin on a typical qualifying order covers the blended average, not the cheapest zone.
Whichever you choose, rerun the numbers when your carrier publishes a new price list.
Comparing your number with a 3PL quote
If you're weighing a fulfillment warehouse, compare the all-in cost per order: your postage average plus packaging plus packing time against the 3PL's total per order. Quotes are built differently. Some 3PLs charge a pick-and-pack fee and bill postage on top; others fold postage into one per-order rate. Compare the postage line on an actual quote with your own average rather than assuming either side wins.
Simpl ships every order from one warehouse in Austin, using UPS, USPS, and FedEx. Our pricing starts at $7/order, a flat per-order rate that includes picking, packing, packaging and postage; carrier surcharges, when they apply, are billed per our terms. There's a $750/month minimum, billed pay-the-difference: if a month's order charges come in under $750, we bill the difference. That's roughly 90–100 orders a month for light packages on standard shipping, and heavier, larger or faster shipments reach it with fewer orders. If you ship well below that, packing orders yourself for now is often the cheaper choice. Our pricing page lists what's included.