If you've ever looked at a freight invoice and wondered why the rate you were quoted isn't what you paid — fuel surcharges are usually the reason. Here's exactly how they work.
A fuel surcharge (FSC) is a variable fee added to base freight rates to cover the cost of diesel fuel. Because diesel prices change weekly, carriers and brokers add a surcharge that adjusts with the market rather than baking an uncertain fuel cost into the base rate.
Fuel typically represents 25–35% of a carrier's total operating cost. When diesel spikes, carriers pass that cost to shippers through the FSC.
Most carriers and brokers use the Department of Energy (DOE) weekly retail diesel price as the benchmark. The surcharge is then applied as a percentage of the linehaul rate or as a cents-per-mile figure.
Example: If diesel is $3.80/gallon and the carrier's FSC table says that triggers a 28% surcharge, a $2,000 linehaul rate becomes $2,560 all-in.
The DOE publishes updated diesel prices every Monday at eia.gov. Most carriers update their FSC tables weekly based on this number.
Some brokers (including IZY Logistics) quote all-in rates — the fuel surcharge is already included in the number you see. Others quote a base rate and add FSC separately on the invoice. Always ask which method your broker uses before approving a quote.
All-in pricing is cleaner and eliminates surprises on the invoice. If a broker is quoting you a base rate, ask: "What is the FSC and what is it based on?"
With national diesel averaging around $3.65/gallon in May 2026, most carriers are running FSC in the 26–30% range on linehaul. This is moderate by historical standards — 2022 saw FSC exceed 40% when diesel hit $5.70/gallon nationally.
IZY Logistics is a licensed freight broker (MC #1615290) serving shippers across the United States. Get a competitive quote in under 30 seconds.
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