How We Calculate
The exact formulas behind every calculator on this site, pallet fit, CBM, dimensional weight, freight density and container fit, and where each one stops being exact.
The principle: geometry and physics only
Every tool here is a dimensional, weight or volume calculation. We never touch cost, rates or classification rules that change with a contract, those belong to your carrier. What we compute is the math that does not change: how many rectangular boxes fit in a rectangular space, how to turn dimensions into volume, and how to compare actual weight against a volumetric figure. All of it runs in your browser; nothing you type is sent to a server.
Below is the formula for each of the five calculator families, followed by the limits you should know before trusting a result.
The five formulas
1. Pallet fit (boxes per pallet)
We lay boxes flat on the deck and count how many fit per layer, then stack layers to the chosen height.
- Per layer (one orientation):
floor(palletL / boxL) x floor(palletW / boxW) - Per layer (rotated):
floor(palletL / boxW) x floor(palletW / boxL), we take the larger of the two - Layers:
floor((maxHeight - palletDeck) / boxH) - Total:
boxesPerLayer x layers
Worked on a GMA 48 x 40 in pallet (deck 5.6 in) with a 12 x 10 x 8 in box to a 60 in load: floor(48/12) x floor(40/10) = 4 x 4 = 16 per layer; floor((60 - 5.6) / 8) = 6 layers; 96 boxes. See the pallet calculator and TI-HI calculator.
2. CBM (cubic meters)
Volume is length x width x height with every edge converted to meters first.
CBM = (L x W x H) in meters, and ft3 = CBM x 35.3147.
A 100 x 80 x 60 cm carton: 1.0 x 0.8 x 0.6 = 0.48 CBM (16.95 ft3). For mixed loads we sum CBM x quantity across rows. See the CBM calculator and what CBM means.
3. Dimensional / volumetric weight
A carrier bills the greater of real weight and a volume-derived figure.
dimWeight = (L x W x H) / divisor, in the matching unit; chargeable = max(actual, dimWeight).
Divisors we use: generic 166 in3/lb or 5000 cm3/kg; FedEx and UPS 139 in3/lb domestic; USPS 166 in3/lb; DHL Express 5000 cm3/kg; air freight (IATA) 6000 cm3/kg. A 20 x 15 x 10 in box at 166: 3000 / 166 = 18.1 lb. See the dimensional weight calculator.
4. Freight density (PCF) and class estimate
density = weight (lb) / volume (ft3), where ft3 = (L x W x H in inches) / 1728.
A 48 x 40 x 48 in pallet at 400 lb: volume = 53.33 ft3, density = 7.5 PCF. We then read an estimated class from a density band (about 125 here). See the freight density calculator.
5. Container / vehicle fit
We fit pallets or boxes into the usable interior of a known container using the same floor-pattern logic as the pallet tool, then count tiers by interior height.
floorCount = best of floor(intL / itemL) x floor(intW / itemW) and the rotated arrangement; tiers = floor(intH / itemH); total = floorCount x tiers. Interiors come from the table on each page (for example a 40 ft dry container is 12032 x 2352 x 2393 mm). See the container load calculator.
Where the math stops
| Calculator | Known limit |
|---|---|
| Pallet & container fit | Single-orientation, axis-aligned packing. We do not mix orientations within a layer, model overhang, pinwheel patterns or irregular shapes. |
| CBM & volume | Pure geometry, it assumes a true rectangular box and ignores how items nest or compress. |
| Dimensional weight | The divisor and rounding rules you select; your carrier's contract may round or round up differently. |
| Freight density / class | Class is an estimate from density only. NMFTA moved to a density-based NMFC model in July 2025 and revises it periodically, so verify the current class with your carrier or NMFTA. |
Use the numbers to plan and sanity-check. Confirm anything that drives a booking with the party who will actually move the freight.