If you ship freight, you have probably looked at a freight invoice and wondered why the total does not match the quote you received. The difference is not an error — it is the result of how US freight shipping rates are structured. Rates are not a single number. They are a combination of base charges, surcharges, and accessorial fees that together determine what you actually pay.
This guide explains what drives freight shipping rates in the US, how to read a quote, and how to get the most accurate pricing for your shipments.
The six factors that drive freight shipping rates
1. Distance
Distance is the primary driver of freight cost. The further your shipment travels, the more it costs — but not linearly. The per-mile rate decreases as distance increases because the carrier's fixed costs (loading, unloading, paperwork) are spread across more miles. A 100-mile shipment may cost $3.00 per mile, while a 1,000-mile shipment may cost $1.50 per mile.
2. Weight
Heavier shipments cost more — but the rate per hundred pounds decreases as weight increases. This is because the carrier's fixed costs (loading, unloading, billing) are the same whether the shipment is 500 pounds or 5,000 pounds. A 5,000-pound shipment does not cost ten times as much as a 500-pound shipment.
3. Freight class (NMFC)
Freight class is the National Motor Freight Classification (NMFC) system — a standardized way of categorizing freight based on density, stowability, handling, and liability. There are 18 classes, ranging from 50 (least expensive per pound — dense, easy to handle) to 500 (most expensive per pound — lightweight, bulky, or high-value).
A shipment of steel brackets (class 50) costs less per pound than a shipment of ping-pong balls (class 500) at the same weight and distance. Misclassifying your freight is the most common reason for invoice adjustments — the carrier inspects the shipment, re-classes it, and bills you for the difference.
4. Fuel surcharges
Fuel surcharges adjust the base rate based on current diesel prices. The surcharge is recalculated weekly using the US Energy Information Administration's national average diesel price. When diesel rises, the surcharge increases; when it falls, it decreases.
A typical fuel surcharge in 2026 ranges from 20 to 35 percent of the base rate, depending on the carrier and the current diesel price. You cannot negotiate the fuel surcharge — it is a pass-through cost.
5. Accessorial charges
Accessorials are charges for services beyond standard dock-to-dock delivery. Common accessorials include:
| Accessorial | Typical Cost | When It Applies | |-------------|-------------|----------------| | Liftgate | $25 to $45 | No loading dock at pickup or delivery | | Residential delivery | $25 to $50 | Delivery to a residential address | | Inside delivery | $50 to $100 | Driver carries freight inside the building | | Detention | $50 to $100/hr | Shipper or receiver keeps driver beyond 2 hours | | Re-class | $25 to $75 | Freight class corrected by carrier | | Re-weigh | $25 to $50 | Weight corrected by carrier |
Accessorials are where quotes and invoices most often diverge. If you need a liftgate but did not request it on the quote, you will see a $25 to $45 charge on the invoice.
6. Lane balance and market conditions
Freight rates are not just about your shipment — they are about the carrier's entire network. If a carrier has a truck returning empty from Seattle to Kent (an empty lane), they will offer a lower rate to fill it. If every carrier is booked solid during peak season, rates rise.
This is why the same shipment may cost different amounts on different days, or from different carriers. The carrier with the best lane balance for your route will offer the best rate.
LTL vs FTL: which rate structure applies?
LTL (less-than-truckload) — your shipment shares trailer space with other shippers. You pay for the space and weight you use, prorated against the total. LTL rates are calculated per hundred pounds (hundredweight) based on class, distance, and discounts. LTL is cost-effective for shipments between 150 and 15,000 pounds.
FTL (full truckload) — your shipment fills an entire trailer. You pay a flat rate per mile or a door-to-door rate regardless of how full the trailer is. FTL is cost-effective for shipments over 15,000 pounds or when you need dedicated transit (no stops, no other freight).
How to get an accurate freight quote
To get a quote that matches your invoice, provide:
- Origin and destination zip codes — exact addresses, not just cities
- Total shipment weight — scaled weight, not estimated
- Number of pieces and dimensions — length x width x height for each piece
- Freight class — if you know it (your carrier can help determine it)
- Pickup and delivery conditions — business hours, residential, liftgate, inside delivery
- Special requirements — hazmat, temperature control, high-value, time-critical
The more precise your information, the more accurate your quote. Estimated weights and guessed freight classes are the most common causes of invoice adjustments.
Freight rates in the Pacific Northwest
SeaSound Transport is a Kent, WA-based freight carrier serving the Puget Sound and broader Pacific Northwest. We provide LTL and FTL quotes for shipments throughout Washington, Oregon, and surrounding states. Our team can help you determine freight class, calculate total costs including accessorials, and plan the most cost-effective routing for your shipment.
Call 206-427-6615 or email Contact@seasoundtransport.com for a freight shipping quote. Provide your origin, destination, weight, and dimensions, and we will return a detailed rate breakdown with no hidden charges.