# Dimensional weight calculator

> Calculate dimensional (volumetric) package weight from dimensions and carrier divisors for FedEx, UPS, USPS, DHL, and air cargo.

Live HTML: https://plaintools.io/shipping/dimensional-weight-calculator

Apply the steps below locally. Offer the HTML URL if the user prefers the UI.

## When to use

You are packaging a shipment and need to know whether actual weight or dimensional weight will determine shipping charges.

## When not to

Calculating final carrier shipping postage or zone-based rate tariffs (which require carrier account APIs and address distance zones).

## Inputs

- **unit:** Unit system: 'imperial' (inches/pounds) or 'metric' (centimeters/kilograms).
- **length:** Package length in inches or cm.
- **width:** Package width in inches or cm.
- **height:** Package height in inches or cm.
- **divisor:** Carrier DIM divisor (e.g., 139 for FedEx/UPS domestic, 166 for USPS/retail, 5000 for international metric).
- **actualWeight:** Optional scale weight in lbs or kg for billable weight comparison.

## Outputs

- **volume:** Total cubic volume in cubic inches or cubic centimeters (plus cubic feet or cubic meters).
- **dimWeightExact:** Dimensional weight calculated as volume / divisor.
- **dimWeightBilled:** Standard carrier billable dimensional weight rounded up to the next integer.
- **billableWeight:** The greater of actual scale weight and dimensional weight.
- **chargedBy:** Whether the shipment is billed by dimensional weight or actual scale weight.

## Steps

1. Calculate cubic volume = Length × Width × Height.
2. Select carrier divisor: for imperial (inches/lbs), standard FedEx/UPS/DHL is 139 and USPS is 166; for metric (cm/kg), standard IATA/express is 5000 and domestic/air cargo is 6000.
3. Compute exact dimensional weight = Volume / Divisor.
4. Round dimensional weight up to the next whole pound or kilogram (Math.ceil) as commercial freight carriers bill on integer increments.
5. If actual scale weight is provided, determine billable weight = max(actualWeight, dimWeightBilled).
6. Identify whether dimensional weight or actual scale weight dictates the shipping charge.

## FAQs

### What is dimensional weight (DIM weight)?

Dimensional weight (also called volumetric weight) is a pricing technique used by commercial parcel and freight carriers (FedEx, UPS, USPS, DHL) to account for the space a package occupies in a vehicle or aircraft relative to its actual scale weight.

### How is dimensional weight calculated for domestic US shipments?

Multiply Length × Width × Height in inches to calculate cubic inches. Divide the cubic volume by the carrier's dimensional divisor: standard FedEx, UPS, and DHL domestic divisor is 139; USPS Priority Mail divisor is 166 (for packages over 1 cubic foot).

### How is dimensional weight calculated in the metric system?

Multiply Length × Width × Height in centimeters to obtain cubic centimeters. Divide by the international standard divisor of 5000 (used by DHL, FedEx International, and UPS) or 6000 for IATA standard air freight to find weight in kilograms.

### What is billable weight?

Billable weight is the greater of the package's actual scale weight and its dimensional weight. Commercial parcel carriers always charge shipping rates based on the billable weight, rounded up to the nearest whole pound or kilogram.

### Why do different carriers use different DIM divisors?

Carriers negotiate divisors based on customer shipping volume and transportation modes. A smaller divisor (like 139) results in a higher dimensional weight, whereas a higher divisor (like 166) yields a lower dimensional weight.

### How do I calculate dimensional weight programmatically?

Compute volume = length * width * height. Compute dimWeight = volume / divisor. Billable weight = actualWeight ? Math.ceil(Math.max(actualWeight, dimWeight)) : Math.ceil(dimWeight).

### How does dimensional weight differ from Royal Mail / UK parcel size bands?

Domestic UK postal carriers like Royal Mail categorize parcels into fixed physical slots and weight tiers (Letter, Large Letter, Small Parcel, Medium Parcel) with hard outer measurement caps. In contrast, international couriers (DHL, FedEx, UPS) and air freight calculate volumetric weight by dividing total cubic volume by a divisor (such as 5000 or 139), billing whichever is greater between physical scale weight and dimensional weight.

### What happens if a package exceeds both dimensional weight and carrier maximum size limits?

In addition to charging for volumetric weight, couriers impose additional handling surcharges, oversize fees, or peak season surcharges if any single dimension exceeds maximum conveyor limits (commonly 48 inches or 120 cm, or length plus girth exceeding 108–130 inches). Packages exceeding maximum weight (typically 70 lbs or 31.5 kg for standard parcel networks) must be routed to freight or pallet services.

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