Dimensional Weight Calculator
Calculate DIM weight and billable weight for UPS, FedEx, USPS, or a custom divisor.
Last reviewed September 6, 2026
How to use this calculator
- Choose the Carrier / DIM Rule that matches how you actually ship — UPS Daily or Retail Rates, FedEx, USPS Priority Mail, USPS Ground Advantage, or a Custom Divisor if you know your own carrier's number.
- Enter the package's length, width, and height in inches.
- Enter the actual weight as pounds and ounces.
- Press Calculate.
- Check Billable / Chargeable Weight first — that's the number that matters for shipping cost — then the detailed breakdown to see exactly how it was built.
What is dimensional weight?
Dimensional (DIM) weight is a way of pricing a shipment based on how much space it takes up in a truck or plane, not just how heavy it is. Carriers calculate it from a package's length, width, and height, then compare that figure to the package's actual weight — you're billed based on whichever one is greater. A large, light box (like a lampshade or a stack of pillows) can end up billed at a much higher weight than its bathroom-scale reading, because it takes up space that a denser package of the same actual weight wouldn't.
DIM weight vs. actual weight vs. billable weight
Actual weight is what the package weighs on a scale. Dimensional weight is calculated from the package's dimensions using a carrier-specific formula and divisor. Billable weight (also called chargeable weight) is whichever of the two is greater — that's the number a carrier actually uses to price the shipment. This calculator shows all three separately, plus which one controlled the result, so you can see exactly why your billable weight came out the way it did.
How each preset is calculated
Every preset rounds each dimension up to the next whole inch before multiplying — a formula never uses a fractional inch. Dividing by different divisors is exactly why the same box can produce a different DIM weight under UPS Daily Rates than under UPS Retail Rates.
UPS — Daily Rates and Retail Rates
Rounded Dimensions = ceil(Length), ceil(Width), ceil(Height) — each to the next whole inch
Cubic Volume = Rounded Length x Rounded Width x Rounded Height
DIM Weight (raw) = Cubic Volume / Divisor — Daily Rates divisor: 139, Retail Rates divisor: 166
Rounded DIM Weight = ceil(DIM Weight (raw))
Actual Rated Weight = ceil(Actual Weight in pounds)
Billable / Chargeable Weight = greater of Actual Rated Weight and Rounded DIM WeightUPS applies no minimum cubic-volume threshold — DIM weight is always calculated and compared, even for small packages. Daily Rates apply on a UPS shipping account; Retail Rates apply when paying at a UPS Store or staffed location without one.
FedEx
DIM Weight (raw) = Cubic Volume / 139
Rounded DIM Weight = ceil(DIM Weight (raw))
Actual Rated Weight = ceil(Actual Weight in pounds)
Billable / Chargeable Weight = greater of Actual Rated Weight and Rounded DIM WeightThis models FedEx's standard divisor for ordinary customer-packaged shipments. Freight services, FedEx International Deferred Freight, and oversize minimum billable weight rules are not modeled.
USPS Priority Mail and USPS Ground Advantage
If Cubic Volume <= 1,728 in³ (1 cubic foot): DIM weight does not apply. Billable / Chargeable Weight = Actual Rated Weight.
If Cubic Volume > 1,728 in³:
DIM Weight (raw) = Cubic Volume / 139
Rounded DIM Weight = ceil(DIM Weight (raw))
USPS DIM Pricing Weight = the lesser of Rounded DIM Weight and 70 lb
Billable / Chargeable Weight = greater of Actual Rated Weight and USPS DIM Pricing WeightPriority Mail rates actual weight in whole pounds (any fraction rounds up). USPS Ground Advantage instead uses ounce tiers under 1 lb: 4 oz, 8 oz, 12 oz, and 15.999 oz, then whole-pound increments from 1 lb through 70 lb. Both apply only to domestic zones 1–9, rectangular parcels. Rounded DIM Weight is always shown even when it exceeds 70 lb — only the separate USPS DIM Pricing Weight is capped.
Custom Divisor
DIM Weight (raw) = Cubic Volume / your divisor
Rounded DIM Weight = ceil(DIM Weight (raw))
Actual Rated Weight = ceil(Actual Weight in pounds)
Billable / Chargeable Weight = greater of Actual Rated Weight and Rounded DIM Weight
(No cubic-volume threshold is applied in this mode.)Use this if you have a divisor from your own carrier account or rate agreement that isn't one of the presets above. This is a generic estimate — it doesn't claim to reproduce every carrier's complete rounding or rating methodology, so verify it matches your actual agreement.
Divisor and rule summary
A quick reference for every preset this calculator supports.
| Preset | Divisor | DIM threshold | 70-lb DIM cap | Actual-weight rounding |
|---|---|---|---|---|
| UPS — Daily Rates | 139 | None | No | Whole pound |
| UPS — Retail Rates | 166 | None | No | Whole pound |
| FedEx | 139 | None | No | Whole pound |
| USPS Priority Mail | 139 | > 1,728 in³ | Yes | Whole pound |
| USPS Ground Advantage | 139 | > 1,728 in³ | Yes | 4 / 8 / 12 / 15.999 oz tiers, then whole pound |
| Custom Divisor | User-entered | None | No | Whole pound |
USPS presets apply to domestic zones 1–9, rectangular parcels only. Custom Divisor is a generic estimate, not a guarantee it matches your specific carrier agreement.
How to reduce DIM weight
Since DIM weight is driven by box size, the most direct way to lower it is to ship in the smallest box that safely fits the product — even trimming an inch off one side can matter, since every dimension rounds up to a whole inch before the calculation. Removing unnecessary void fill, choosing a snugger box, or repackaging an oddly-shaped item into a more compact shape can all reduce cubic volume and, in turn, dimensional weight.
Assumptions and Limitations
- This is a dimensional (DIM) weight and billable weight calculator — it does not calculate a postage or shipping price in dollars.
- Domestic US parcel shipments only. Rectangular parcels only — non-rectangular / irregularly shaped parcel formulas are not modeled in this version.
- USPS presets model domestic zones 1–9 only, per official USPS rules.
- UPS and FedEx presets don't model freight, LTL/pallet shipments, FedEx International Deferred Freight, oversize minimum billable weight rules, or other special minimum billable weight surcharges. This calculator doesn't model customs, duties, or connect to any carrier's API — every figure comes from what you enter, not a live account or shipment.
- No fuel, residential, delivery area, or remote-area surcharges, declared value, signature fees, or negotiated-rate presets are modeled — use Custom Divisor for a negotiated or account-specific divisor.
- Carrier package-size limits, oversize rules, additional handling rules, and other eligibility requirements are not fully checked by this calculator.
- Custom Divisor is a generic estimate — it applies one documented rounding convention and does not claim to reproduce every carrier's complete rating methodology.
- This is an estimate based on the numbers you enter and the selected carrier rule — it is not a live readout from a carrier account and may not match your actual invoice exactly.
- This calculator is for general informational purposes only and is not tax, financial, legal, or investment advice.
See our methodology for how we build, document, and review every calculator's formulas.
Worked example
An 18 x 14 x 8 in box weighing 3 lb, shipped UPS Daily Rates.
- Rounded Dimensions
- 18 × 14 × 8 in
- Cubic Volume
- 2,016 in³
- Raw DIM Weight
- 14.50 lb
- Rounded DIM Weight
- 15 lb
- Actual Rated Weight
- 3 lb
- Billable / Chargeable Weight
- 15 lb
- Weight That Controls Billing
- Dimensional weight
Worked example
The same box shipped UPS Retail Rates instead — the divisor is the only thing that changes.
- Cubic Volume
- 2,016 in³
- Divisor Used
- 166
- Rounded DIM Weight
- 13 lb
- Billable / Chargeable Weight
- 13 lb
Worked example
A large, light 24 x 24 x 24 in box weighing 10 lb, shipped USPS Priority Mail — the 70-lb DIM pricing cap applies.
- Cubic Volume
- 13,824 in³
- Raw DIM Weight
- 99.45 lb
- Rounded DIM Weight
- 100 lb
- USPS DIM Pricing Weight
- 70 lb (capped)
- Actual Rated Weight
- 10 lb
- Billable / Chargeable Weight
- 70 lb
- Weight That Controls Billing
- USPS 70-lb DIM pricing cap
Worked example
A small 12 x 12 x 12 in box weighing 5 lb, shipped USPS Ground Advantage — exactly at the 1-cubic-foot threshold, so DIM weight doesn't apply.
- Cubic Volume
- 1,728 in³
- Rounded DIM Weight
- N/A
- Actual Rated Weight
- 5 lb
- Billable / Chargeable Weight
- 5 lb
- Weight That Controls Billing
- Actual weight — USPS DIM weight does not apply.
Frequently asked questions
What is dimensional weight?
Dimensional (DIM) weight is a way carriers price shipments based on package size, not just actual weight. It's calculated from a package's length, width, and height using a carrier-specific formula and divisor, then compared against the package's actual weight — the greater of the two is what the carrier bills.
How do I calculate DIM weight?
Round each dimension up to the next whole inch, multiply length x width x height to get cubic volume, then divide by the carrier's divisor and round up to the next whole pound. This calculator does that math for you and shows every step.
What DIM divisor does UPS use?
UPS uses 139 for Daily Rates and 166 for Retail Rates — the same box can produce a different DIM weight depending on which rate type applies to your account. Choose whichever matches your actual UPS pricing.
What DIM divisor does FedEx use?
This calculator models FedEx's standard 139 divisor for ordinary customer-packaged shipments. Freight services and certain oversize or minimum-billable-weight rules use different rules not modeled here.
What DIM divisor does USPS use?
USPS Priority Mail and USPS Ground Advantage both use a divisor of 139, applied only once a package's rounded volume exceeds 1 cubic foot (1,728 cubic inches) and only for domestic zones 1–9.
When does USPS dimensional weight apply?
Only when a rectangular package's rounded volume exceeds 1,728 cubic inches (1 cubic foot), and only for domestic delivery to zones 1–9. Smaller packages are always billed at actual weight, with no dimensional-weight comparison at all.
Does USPS dimensional weight apply at exactly 1 cubic foot?
No. The rule only applies once volume exceeds 1,728 cubic inches — a package at exactly 1,728 cubic inches (12 x 12 x 12 in, for example) is billed at actual weight only, with no dimensional-weight comparison.
How does USPS Ground Advantage round actual weight under 1 lb?
USPS Ground Advantage bills actual weight under 1 lb at four ounce tiers — 4 oz, 8 oz, 12 oz, and 15.999 oz — rounding any weight up to the next tier. At 1 lb and above, any fraction of a pound rounds up to the next whole pound instead. USPS Priority Mail doesn't use these ounce tiers — it rounds straight to the next whole pound at any weight.
What is billable weight?
Billable weight (also called chargeable weight) is whichever is greater: a package's actual weight or its dimensional weight. That's the number a carrier uses to price the shipment — not necessarily the number on your bathroom scale.
What does Billable Weight Increase mean?
It's how much greater your Billable / Chargeable Weight is than your Actual Rated Weight, as a percentage — a way to see how much dimensional weight affected your result. It's a weight comparison only, not a shipping-price increase; a 400% billable weight increase does not mean your shipping cost quadruples.
Why is my dimensional weight higher than actual weight?
This happens with large, lightweight packages — a big box with a lot of empty or low-density space inside takes up room in a truck or plane out of proportion to how much it weighs, so the carrier's formula produces a higher number based on size than the scale does based on weight.
How can I reduce DIM weight?
Use the smallest box that safely fits the product. Every dimension rounds up to a whole inch before the calculation, so even trimming an inch off one side, removing unnecessary void fill, or repackaging into a more compact shape can lower cubic volume and DIM weight.
Does this calculator tell me my shipping cost?
No. This is a dimensional weight and billable weight calculator, not a live rate-quoting tool — it doesn't calculate a postage or shipping price in dollars. Use your carrier's own rate chart or account pricing against the billable weight this calculator produces.
What is USPS's 70-lb DIM pricing cap?
For USPS Priority Mail and USPS Ground Advantage, if the calculated dimensional weight exceeds 70 lb, USPS caps the DIM pricing weight at the 70-lb price rather than charging for the full calculated figure. This calculator always shows the true, uncapped DIM weight alongside the capped USPS pricing weight, so you can see both.
Why do UPS Daily Rates and Retail Rates give different results?
They use different divisors — 139 for Daily Rates and 166 for Retail Rates — applied to the exact same cubic volume. A larger divisor produces a lower DIM weight, so the same box can be billed differently depending on which rate type applies to your account.
What should I enter for Custom Divisor?
Enter the divisor from your own carrier account or rate agreement if it isn't one of the built-in presets. This mode is a generic estimate — it applies one documented rounding convention and doesn't claim to reproduce every carrier's complete rating methodology, so double-check it against your actual agreement.
Sources
Carrier rules are sourced directly from each carrier's own official documentation, last reviewed 2026-09-06.
- UPS — Shipping Dimensions and Weight
- FedEx — What Is Dimensional Weight?
- FedEx Service Guide 2026
- USPS Domestic Mail Manual 123 — Priority Mail Prices and Eligibility
- USPS Domestic Mail Manual 133 — USPS Ground Advantage Retail Prices and Eligibility
- USPS Domestic Mail Manual 223 — Priority Mail Commercial Prices and Eligibility
- USPS Domestic Mail Manual 283 — USPS Ground Advantage Commercial Prices and Eligibility
Comparing 3PL or fulfillment costs alongside your shipping weight? See the 3PL Fulfillment Cost Calculator to turn your actual 3PL quote into a true monthly fulfillment cost.
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