DIM Divisor as a Density

Also known as dim divisor · dimensional weight divisor · DIM factor · volumetric divisor · 139 divisor · 166 divisor · 5000 divisor · 6000 divisor · what does divisor 139 mean · convert dim divisor to density

\rho_{\mathrm{dim}} = \frac{m_b}{d \, V_b}

Enter your known values, leave one input blank, and solves for the missing one. Try different units for next level excitement!

Learning zone

Ask a carrier why the divisor is 139 and you will get an answer about industry practice. Ask what 139 is and the conversation usually stops. It is worth pushing, because the answer is simple and it is arithmetic you can check yourself.

A divisor is a specific volume — volume per unit mass. It says: 139 cubic inches of space is what one pound of billing buys. Flip it and you have a density. One pound per 139 cubic inches, and since a cubic foot is 1728 cubic inches, that is 1728/139 = 12.43 pounds per cubic foot. Do the same to 166 and you get 10.41 lb/ft³. Those two numbers are the whole of the parcel-pricing world's dimensional rules, expressed in a unit a warehouse can actually use.

Now the part that surprised me the first time I worked it through. The conversion factor between the two ways of writing a divisor is fixed: one cubic inch is 16.387064 cm³, and one kilogram is 2.2046226 lb, so one in³/lb is 36.1273 cm³/kg. Run the famous numbers through it. 139 × 36.1273 = 5,022. 166 × 36.1273 = 5,997. The metric tariffs print 5,000 and 6,000. The imperial and metric divisors are one rule written twice, converted and then rounded to something a rate sheet can display without embarrassment. They were never two independent conventions, and anybody who offers you a separate origin story for 6,000 is telling you a story.

A divisor without its units is worthless. This is why the page above makes you declare the basis rather than guessing it. 139 in³/lb is a density of 12.4 lb/ft³; 139 cm³/kg would be a density of 7,194 kg/m³, denser than steel, and no pricing rule has ever meant that. The units are the part most often left off the sheet the number is printed on, and the site has no specific-volume unit type that could convert a bare 139 for you. Naming the volume unit and the mass unit yourself is the honest way through, and it is the same treatment this site gives Taylor's constant in the machining shard, for the same reason: a number lifted from a table has to be entered in the units that table was written in, and no calculator can guess which.

One more caution, and it is the important one. A divisor is a price, not a fact. It is set by each carrier, it differs between services, it changes — USPS moved from 166 to 139 in July 2026 — and large shippers negotiate it as a contract term. Published divisors describe list rates only. If you are being charged a divisor you did not agree to, or you want a better one, the arithmetic on this page is how you turn the argument into a number: pick the density you want the break-even to sit at, and solve for the divisor that puts it there.

DIM Divisor as a Density

\rho_{\mathrm{dim}} = \frac{m_b}{d \, V_b}

Where

$\rho_{\mathrm{dim}}$ = Dimensional density (kg/m³)
$d$ = DIM divisor (bare number from the tariff)
$V_b$ = Basis volume — the unit the divisor counts (cm³)
$m_b$ = Basis mass — the unit the divisor is per (kg)

Missing one of these? Work it out first, then come back

Dimensional density — Dimensional Weight, Shipment Density
DIM divisor (bare number from the tariff) — Cube Utilisation, Weight Utilisation
Basis volume — the unit the divisor counts — Dimensional Weight, Shipment Density
Basis mass — the unit the divisor is per — Dimensional Weight, Chargeable Weight