Freight Class Calculator
Estimate the freight cost of an LTL (less-than-truckload) shipment by computing density and applying the per-hundred-pound rate, plus accessorial fees. Use it for B2B logistics planning where pallet density determines NMFC freight class and ultimately what you pay.
Last updated: May 2026
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About this calculator
The formula combines density calculation with rate application: density = weight (lb) ÷ volume (cubic feet); freight class is then assigned from a density-to-class lookup table (50, 55, 60, 65, 70, 77.5, 85, 92.5, 100, 110, 125, 150, 175, 200, 250, 300, 400, 500), and total cost = (weight ÷ 100) × rate-per-CWT + accessorial fees. Volume in cubic feet = (length × width × height in inches) ÷ 1728. Lower classes (50, 55, 60) correspond to denser cargo that's cheaper to ship per pound; higher classes (400, 500) are for low-density freight that's expensive per pound. Approximate density-to-class mapping: density > 50 lb/ft³ = class 50, 35–50 = class 55, 30–35 = class 60, 22.5–30 = class 65, 15–22.5 = class 70, 13.5–15 = class 77.5, 12–13.5 = class 85, 10.5–12 = class 92.5, 9–10.5 = class 100, 8–9 = class 110, 7–8 = class 125, 6–7 = class 150, 5–6 = class 175, 4–5 = class 200, 3–4 = class 250, 2–3 = class 300, 1–2 = class 400, < 1 = class 500. The National Motor Freight Classification (NMFC), published by the National Motor Freight Traffic Association (NMFTA), assigns specific items to specific classes regardless of density in some cases — chemicals, hazardous materials, and certain commodities have fixed classes from the NMFC tariff. Rate per CWT (per hundred pounds) varies by carrier, origin-destination lane, and freight class; typical rates range $15–$80/CWT for ground LTL freight across major lanes. Edge cases: missing pallets or pieces produce zero volume and undefined density; very low-density shipments (heaters, lampshades, light fixtures) get class 400–500 with substantially higher per-pound costs.
How to use
Example 1 — Standard pallet of dense product. A 48×40×48 inch pallet weighing 800 lb, with a rate of $32/CWT and $25 in accessorial fees (lift-gate delivery). Volume = 48×40×48 / 1728 = 92,160 / 1728 ≈ 53.3 cubic feet. Density = 800 / 53.3 ≈ 15.0 lb/ft³ → freight class 77.5. Cost = (800 / 100) × 32 + 25 = 8 × 32 + 25 = 256 + 25 = $281. Verify: matches the formula. ✓ Solid density at 15 lb/ft³ puts this in a favorable class; cargo that's denser (machinery, metals, dense building materials) gets even better classes. Example 2 — Bulky lightweight LTL shipment. A 48×40×72 inch pallet weighing 250 lb (large light items like foam, packaging materials, plastic bins), rate $42/CWT, accessorials $40 (residential + lift-gate). Volume = 48×40×72 / 1728 = 138,240 / 1728 = 80 cubic feet. Density = 250 / 80 = 3.125 lb/ft³ → freight class 250. Cost = (250 / 100) × 42 + 40 = 2.5 × 42 + 40 = 105 + 40 = $145. Verify: total reflects the lower base cost due to lower weight but the high freight class makes per-pound shipping expensive. ✓ At $145 for 250 lb that's $0.58/lb — much higher than the $0.32/lb in Example 1 — driven by the class-250 designation from the low density.
Frequently asked questions
What is freight class and why does density determine it?
Freight class is a NMFC-defined commodity classification that determines LTL shipping rates. The system was developed by the National Motor Freight Traffic Association in the 1930s to standardize freight pricing across carriers. There are 18 classes ranging from 50 (densest, cheapest per pound) to 500 (lightest, most expensive). Density is the primary factor because, like dimensional weight in parcel shipping, freight density determines how efficiently a shipment fills the truck. A truck can carry 45,000 lb at maximum, but if the cargo is so light that it fills the volume before reaching the weight limit, the carrier is missing revenue opportunity per cubic foot. Pricing by class equalizes carrier revenue per cubic foot of trailer space. Beyond density, NMFC also considers stowability (how stackable and stable), handling (special equipment required), and liability (value, fragility, theft risk) — so similar-density goods can have different classes if one is more prone to damage or theft.
How do I find my freight class lookup table?
The official NMFC classification is published by NMFTA in a proprietary tariff that LTL carriers subscribe to. Public density-to-class mappings are widely available (and approximated above), but the actual NMFC tariff may classify your specific commodity differently — sometimes by item description regardless of density (chemicals, hazardous materials, classed commodities). For accurate classification: contact your carrier's freight desk or use a digital freight platform (FreightWaves, Project44, etc.) that has access to current NMFC codes. Misclassification is a major source of reclassification fees — if your shipper-declared class is lower than what the carrier determines on arrival, they'll reclass and surcharge, often with steep penalty fees. Whenever uncertain, declare a higher (more expensive) class to avoid reclassification surcharges, then dispute if you have evidence the lower class applies.
What are accessorial fees in LTL shipping?
Accessorials are extra charges for services beyond standard dock-to-dock freight movement. Common ones: residential delivery ($60–$200 per shipment, for non-business addresses), lift-gate service ($40–$80, for locations without loading docks), inside delivery ($50–$200, beyond the dock or doorstep), notification before delivery ($10–$30), limited access ($50–$200 for schools, military bases, churches, etc.), reweigh/reclassification ($25–$200), redelivery attempts ($50–$150), and detention/demurrage for delays beyond free time ($30–$100/hour). These fees frequently dwarf the base freight charge for small shipments — a $80 line-haul charge might come with $200 in accessorials. When budgeting, always assume some accessorials will apply, especially for residential or low-volume B2C deliveries. Provide accurate origin/destination details upfront to get more accurate quotes; mis-specifying location type (commercial vs. residential, accessible vs. limited) generates expensive surprise fees.
What are the most common mistakes people make with LTL freight?
The biggest is misclassifying freight to get a lower rate, then getting hit with reclassification fees that exceed the savings; always classify accurately or err on the safe (higher-class) side. The second is forgetting accessorial fees; the base line-haul rate is often 40–60% of the total cost on small shipments. The third is mismeasuring pallet dimensions — round UP to the nearest inch and remember to include any overhang or protrusions that affect the bounding box. The fourth is shipping a single light item on a large pallet when smaller carriers (parcel-LTL hybrid services) could handle it cheaper; pallets always go LTL but loose items might fit parcel. The fifth is not negotiating rates; LTL carriers heavily discount published tariffs for regular shippers, and TMS (transportation management system) platforms aggregate volume from multiple shippers to access bigger discounts. Finally, many companies ship 5 small pallets when they could consolidate into 2 larger ones, paying for more freight-class minimum charges than necessary.
When should I not use this calculator?
Skip it for parcel shipping (packages under 150 lb or ~108 inches longest dimension) — those go via parcel carriers (UPS, FedEx, USPS), not LTL, and use different pricing entirely; use a parcel rate calculator instead. It is the wrong tool for FTL (full-truckload) shipments where you book an entire truck and pricing is per-mile / per-trip rather than per-CWT / per-class. Do not use it for international ocean freight, air freight, or rail freight — each has its own pricing structure. It is also a poor fit for hazardous materials, refrigerated freight, or oversized/overweight shipments that require special permits and have their own rate sheets. For accurate quotes you can commit to customers, always get a real quote from the carrier or your TMS — this calculator is an estimate that ignores fuel surcharges (currently 30–50% on LTL freight!), accessorials specific to the lane, and any negotiated discounts. And for very high-volume shipping, work with a freight broker or 3PL who can access pricing tiers individual shippers can't match.