Free, no signup. Updated October 2026
Free dimensional weight calculator for UPS, FedEx and USPS
Enter a box size to see what each carrier will bill.
Carriers bill large, light boxes by the space they take up. Enter your box size and weight to see the dimensional weight and the billable weight UPS, FedEx and USPS will charge, using the divisors and rounding rules in effect in 2026. Share the result with a link.
What dimensional weight is and why carriers bill it
A truck runs out of space long before it runs out of weight capacity. Dimensional weight (also called volumetric weight) is how carriers charge for that space, so a big, light box can’t ride for the price of its scale weight.
The formula
Length × Width × Height ÷ the carrier’s DIM factor, rounded up. That’s your dimensional weight in pounds where dimensional pricing applies.
Billable weight wins
The carrier compares DIM weight to your actual scale weight and charges whichever is greater. That higher number is your billable weight, and it’s what your rate is built on.
The factors that matter
UPS and FedEx commercial rates use a 139 divisor; UPS retail uses 166. USPS uses 139 on eligible parcels when the volume after rounding each dimension up exceeds 1 cubic foot. A lower factor means a higher DIM weight.
Where it bites
Light, bulky products like pillows, apparel and anything in oversized packaging are where DIM weight quietly eats your margin, sometimes turning a 2-lb item into a 28-lb charge.
2026 DIM divisors by carrier
The divisor decides how much DIM weight your box racks up. These are the values this calculator applies.
Rounding: each side rounds up to the next whole inch (next whole centimeter for international), and DIM weight rounds up to the next pound (next 0.5 kg for international).
USPS changed its divisor from 166 to 139 on July 12, 2026.
DHL uses dimensional pricing on international shipments too. Check your contract for the exact divisor. A lower factor (139) means a higher DIM weight and a higher bill than a higher factor (166).
How to calculate dimensional weight
Four steps and about a minute. Measure, find the volume, divide by the DIM factor, then take the greater of DIM weight and actual weight.
Step 1
Measure the package
Measure length, width, and height at the widest points, including any bulge in the box. UPS, FedEx, and USPS all round each dimension up to the next whole inch, so a 10.2-inch side is billed as 11. The calculator does this for you.
Step 2
Find the cubic volume
Multiply the dimensions after carrier rounding. For USPS, 12.2×10×10 inches becomes 13×10×10 = 1,300 cubic inches, so DIM weight does not apply. A 12×12×12-inch box is exactly 1,728 cubic inches and also stays below the USPS DIM trigger.
Step 3
Divide by the DIM factor
Divide the volume by your carrier's DIM factor (139 for USPS and UPS/FedEx commercial, or 166 for UPS retail), then round up to the next whole pound. USPS only applies DIM weight when its rounded volume exceeds 1,728 cubic inches.
Step 4
Take the greater number
Round actual weight up to the next whole pound. Where DIM weight applies, take the greater of actual and DIM weight. For USPS at or below 1,728 rounded cubic inches, use rounded actual weight alone. Metric inputs convert to inches and pounds before rating; kilograms shown are equivalents of the rated pounds.
Worked examples
Each row is what this calculator returns for that box. The 1,728 cubic inch line is where USPS starts or stops applying DIM weight.
| Box | Volume | Billable weight |
|---|---|---|
| 14×12×12 in, 3 lb | 2,016 in³ | FedEx: 15 lb. UPS daily: 15 lb. UPS retail: 13 lb. USPS: 15 lb. |
| 12×12×12 in, 2 lb | 1,728 in³ | USPS: 2 lb (DIM weight does not apply). FedEx: 13 lb. UPS daily: 13 lb. UPS retail: 11 lb. |
| 12.2×10×10 in, 2 lb | 1,300 in³ for USPS (13×10×10) | USPS: 2 lb (DIM weight does not apply). |
| 30×20×15 cm, international | 9,000 cm³ | 2.0 kg volumetric weight (9,000 ÷ 5,000 = 1.8, rounded up). |
How to lower your DIM weight charges
Dimensional weight is one of the few shipping costs you can control. It comes down to the box more than the carrier.
Right-size the box
Most brands over-box everything. Cutting even two inches off each dimension drops the cubic volume fast, and a smaller box can lower the billable weight on every order that ships in it. See how to downsize your shipments.
Use poly mailers
If the product isn’t fragile, skip the box. Mailers are measured at their actual, thin dimensions, so the scale weight usually wins instead of DIM weight.
Cut the void fill
Air pillows and crumpled paper inflate the box you need. Less filler means a smaller carton, a smaller DIM weight, and a smaller bill.
Ask about your divisor
High-volume shippers can ask their carrier about a higher DIM divisor in their contract. A higher divisor lowers DIM weight. For small, dense USPS parcels, USPS Cubic pricing is another option.
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Dimensional weight FAQs
- What is dimensional weight?
- Dimensional weight (DIM weight, sometimes called volumetric weight) is a pricing method carriers use to charge for the space a package takes up, not just what it weighs. If a box is large but light, the carrier prices it on its size instead of the scale reading, so a 2-lb pillow in a big box can cost like a 28-lb shipment.
- How do I calculate DIM weight?
- For USPS, round each dimension up to the next whole inch, then multiply length × width × height. If the rounded volume exceeds 1,728 cubic inches, divide by 139 and round up to the next whole pound. Otherwise, DIM weight does not apply. A 14×12×12-inch USPS parcel is 2,016 cubic inches; 2,016 ÷ 139 ≈ 14.50, rounded up to 15 lb. UPS and FedEx commercial shipments use 139; UPS retail uses 166.
- What is billable weight?
- Billable weight is the number your shipping rate is actually based on. The carrier compares your package's DIM weight to its actual (scale) weight and charges whichever is greater. For USPS, round actual weight up to the next whole pound and compare it with DIM weight only when the rounded volume exceeds 1,728 cubic inches; otherwise, billable weight is the rounded actual weight.
- Do UPS, FedEx, USPS, and DHL all use dimensional weight?
- UPS, FedEx, and DHL apply DIM pricing to essentially every package. USPS applies it to eligible Priority Mail Express, Priority Mail, USPS Ground Advantage and Parcel Select parcels, at retail and commercial rates, only when the volume after rounding each dimension up exceeds one cubic foot (1,728 cubic inches), and USPS Flat Rate boxes are exempt. The carriers use different divisors, which is why the same box can be billed at a different weight depending on who you ship with.
- How do I lower my dimensional weight charges?
- Right-size the box. Even shaving two inches off each dimension cuts the cubic volume and the DIM weight noticeably. Use poly mailers instead of boxes for non-fragile items, since they're measured thin enough that actual weight usually wins. Cut excess void fill. High-volume shippers can also ask their carrier about a higher DIM divisor in their contract. A higher divisor lowers DIM weight.
- Is volumetric weight 5,000 or 6,000?
- For metric shipments, many international services divide cubic centimeters by 5,000 to get kilograms, and some contracts use 6,000. Check your carrier contract. This calculator shows the 5,000 divisor when you turn on international volumetric weight.
- Does Amazon FBA use dimensional weight?
- For small standard-size items, Amazon uses the unit weight. For most larger size tiers, it uses the greater of unit weight or dimensional weight. Our guide to Amazon FBA fees explains the size tiers.
- How do I find dimensional weight from length, width and height?
- Round each side up to the next whole inch, multiply length × width × height, divide by the carrier's divisor and round up to the next pound. A 14×12×12-inch box is 2,016 cubic inches, and 2,016 ÷ 139 ≈ 14.50, so its DIM weight is 15 lb.
- Why did my shipping cost more than expected?
- It's almost always dimensional weight. If your package is large relative to what it weighs, the carrier billed you on its dimensions rather than the scale. Run the box through the calculator above to see your real billable weight before you ship.