Dimensional Weight Calculator

Use this dimensional weight calculator to estimate how carriers may bill your packages based on their size, not just their scale weight. Dimensional (or volumetric) weight is especially important for large but lightweight parcels, because most major couriers charge for whichever is higher: the actual weight or the dimensional weight.

What is dimensional weight?

Dimensional weight is a pricing weight that reflects how much space a package takes up in a truck, van, or airplane. Instead of charging only for actual pounds or kilograms, carriers convert the package volume into a weight using a number called the dimensional divisor.

This system prevents very bulky, low-density boxes from crowding out denser, more profitable shipments without paying their fair share of the available cargo space.

Dimensional weight formulas

The basic idea is:

Dimensional Weight = Package Volume ÷ Dimensional Divisor

In imperial units (inches and pounds):

• Length in inches
• Width in inches
• Height in inches
• Divisor often around 139 for many services when using inches

The formula becomes:

Dimensional weight (lb) = (Length × Width × Height) ÷ Divisor

In metric units (centimeters and kilograms):

• Length in centimeters
• Width in centimeters
• Height in centimeters
• Divisor often around 5000 when using centimeters

The formula becomes:

Dimensional weight (kg) = (Length × Width × Height) ÷ Divisor

The same relationship can be expressed with MathML for clarity:

Where:

• D = dimensional weight (lb or kg)
• L = length
• W = width
• H = height
• k = dimensional divisor provided by the carrier

How to use this calculator

1. Measure your package using a tape measure. Record the maximum length, width, and height of the outer box, including any bulges.
2. Select the unit you used to measure (inches or centimeters).
3. Enter the dimensions into the length, width, and height fields.
4. Enter the actual weight from a scale, using the unit that matches your carrier’s rules (pounds if you measured in inches, kilograms if you measured in centimeters in many regions).
5. Set the carrier divisor. Common reference values are:
   • 139 for many domestic and international services when dimensions are in inches.
   • 5000 for many services when dimensions are in centimeters.

   Always verify the current divisor in your carrier’s official pricing guide, because it can change over time and may differ by service.

6. Optional: enter a rate per weight unit (for example, cost per pound or per kilogram) to estimate a simple shipping charge.
7. Run the calculation. The tool will compute the dimensional weight, compare it to the actual weight, and estimate a billed weight based on the higher of the two.

Interpreting your results

The calculator is designed to show three main outputs:

• Dimensional weight – the volume-based weight derived from your package size and divisor.
• Actual weight – the weight from your scale, as you entered it.
• Estimated billed weight – the higher of dimensional and actual weight, which many carriers use for pricing.

Once you have the estimated billed weight, you can multiply it by your rate per weight unit to get an approximate shipping cost. If you entered a rate, the calculator does this multiplication for you.

Use the results as planning guidance:

• If dimensional weight is higher than actual weight, your box is relatively bulky for its weight. You may save money by using a smaller box or reducing empty space.
• If actual weight is higher than dimensional weight, your cost is driven mainly by mass, and changing box size will likely have less impact.
• If both numbers are close, you are using space fairly efficiently, and either factor could drive pricing depending on small changes in carrier rules.

Worked examples

Imperial example (inches and pounds)

Suppose you ship a package with these dimensions:

• Length: 20 in
• Width: 15 in
• Height: 10 in
• Actual weight: 8 lb
• Divisor: 139
• Rate: $1.50 per lb

Step 1: Compute the volume.

Volume = 20 × 15 × 10 = 3000 cubic inches

Step 2: Apply the divisor.

Dimensional weight = 3000 ÷ 139 ≈ 21.6 lb

Carriers usually round up, so the dimensional weight is about 22 lb.

Step 3: Compare with actual weight.

• Actual weight = 8 lb
• Dimensional weight ≈ 22 lb

Because 22 lb is higher than 8 lb, the estimated billed weight is 22 lb.

Step 4: Estimate cost.

Estimated cost = 22 × $1.50 = $33.00

Metric example (centimeters and kilograms)

Now consider a metric shipment:

• Length: 40 cm
• Width: 30 cm
• Height: 20 cm
• Actual weight: 5 kg
• Divisor: 5000
• Rate: $4.00 per kg

Step 1: Compute the volume.

Volume = 40 × 30 × 20 = 24,000 cubic centimeters

Step 2: Apply the divisor.

Dimensional weight = 24,000 ÷ 5000 = 4.8 kg

Carriers often round up, so the dimensional weight is about 5 kg.

Step 3: Compare with actual weight.

• Actual weight = 5 kg
• Dimensional weight ≈ 5 kg

Both values are similar, so the billed weight is likely around 5 kg. Your estimated cost at $4.00 per kg is roughly $20.00.

Comparison of units and typical divisors

These divisors are examples only. Each carrier and service can use different values, and they may change over time.

Tips to reduce dimensional weight charges

• Use the smallest practical box. Avoid oversizing packaging, especially for light items.
• Right-size your void fill. Replace bulky padding with efficient materials that take up less space while still protecting the product.
• Check alternate box sizes. Running dimensions for two or three box options in the calculator can highlight where a small size change lowers the billed weight tier.
• Flatten or disassemble products when possible so they ship in more compact packaging.
• Review your carrier’s rules. Some services use different divisors, dimensional thresholds, or rounding rules that can affect which option is most economical.

Limitations, assumptions, and disclaimer

This dimensional weight calculator is for planning and educational purposes only. It is not a quote tool and does not guarantee any specific shipping price.

Key assumptions and limitations:

• The calculation uses the simple formula of volume divided by a single divisor and does not include fuel surcharges, residential fees, oversized-package fees, remote-area surcharges, taxes, or other adjustments.
• The estimated billed weight assumes that the carrier charges for the greater of dimensional weight or actual weight, which is common but not universal.
• The divisor values shown or pre-filled (such as 139 or 5000) are examples only. Actual divisors depend on the carrier, service level, destination, and the date you ship.
• The tool does not apply minimum billable weights, special freight rules, or zone-based pricing tables.
• Rounding behavior (for example, to the next whole pound or kilogram) can vary between carriers and services.

Always confirm final shipping charges and policies with your chosen carrier or logistics provider before making pricing promises to customers or committing to large shipments.

Last updated: this guidance is periodically reviewed, but dimensional-weight policies can change. Check your carrier’s latest documentation for the most current rules.