Practical miles and shortest miles are two different route calculations from the same mileage engine, and a per-mile freight bill pays whichever one your contract names. Practical routing follows the roads a truck would realistically drive: interstates, truck-legal routes, sensible turns. Shortest routing minimizes distance and will happily send the theoretical truck down a road no driver would take. Practical is almost always the longer number, and it is the industry default for a reason.
The reason this belongs in a fuel surcharge cluster is that on a per-mile truckload contract, miles are an input twice. The linehaul is rate times miles. The fuel surcharge is cents per mile times miles. Change the mileage basis and both lines move together, in the same direction, on every load in the lane.
Most contracts say “PC Miler miles” and stop there. That phrase does not identify a number. It identifies a software product that will return several different numbers for the same origin and destination depending on four settings, and the settings are where the audit is.
The four things that decide the mileage figure
Ask a carrier for the miles on a lane and you get one number. That number is the output of four choices, and a contract that names only the first one has left the other three to whoever runs the rating engine.
1. The engine. PC Miler (Trimble) is the most common in truckload. Rand McNally mileage products, the Household Goods Mileage Guide used in some legacy tariffs, and general-purpose consumer mapping engines all exist in real contracts. Different engines model the road network differently, so they disagree even when both are set to practical routing.
2. The routing type. Practical and shortest are the two you will see named most often. Practical models realistic truck routing. Shortest minimizes distance. Engines typically also offer variants such as toll-avoiding or toll-discouraged routing and routing restricted to designated truck networks. Each returns a different distance, and a toll-avoid setting can add meaningful mileage in the Northeast while saving the carrier a toll it never passed through to you.
3. The version. Mileage engines publish new versions as the road network and the underlying data change. A carrier running an older version and a broker running a current one will produce different mileage on the same lane, both of them honestly. A contract that says “PC Miler” without a version leaves that drift unresolved and unarguable.
4. The address resolution. Whether the calculation runs city-to-city, ZIP-to-ZIP, or street-address-to-street-address changes the endpoints. ZIP centroid to ZIP centroid on a large industrial ZIP code is not the same as dock to dock. Neither is wrong, but they are not the same number, and in dense metros the gap compounds across a lane run weekly.
Multiply the four out and “PC Miler miles” is a family of answers. On a long lane the spread between the shortest and the longest reasonable configuration is a real percentage of the distance, not a rounding artifact, and it is paid on every load.
Why a few miles matter more than they look
Miles hit the invoice twice on a per-mile contract, and the second hit is the one people forget.
Work an illustrative load. All numbers below are illustrative and shaped like real contract terms, not quoted from any carrier.
- Line rate: $2.00 per mile
- Fuel surcharge: $0.4667 per mile, which is the output of a $5.30 index, a $2.50 peg and a 6.0 MPG assumption, computed the way a truckload fuel surcharge is calculated from the DOE index
- Combined: $2.4667 per mile
| Mileage basis (illustrative) | Miles | Linehaul | Fuel | Total |
|---|---|---|---|---|
| Shortest | 604 | $1,208.00 | $281.89 | $1,489.89 |
| Practical | 620 | $1,240.00 | $289.33 | $1,529.33 |
| Practical, toll-avoid | 641 | $1,282.00 | $299.16 | $1,581.16 |
| Difference, shortest to toll-avoid | 37 | $74.00 | $17.27 | $91.27 |
Thirty-seven miles on a 600-mile lane is $91 on this illustrative load. Run that lane twice a week and it is roughly $9,500 a year, on a setting nobody discussed. The fuel component alone is $17 per load, which is why the mileage basis is a fuel surcharge issue and not only a linehaul issue.
Note also what does not happen: the surcharge per mile is unchanged in all three rows. The index, the peg and the MPG are identical. The only thing that moved is the multiplier. That is what makes the mileage basis such a quiet error. Every input you would normally check is correct.
How to audit it without buying the software
You do not need a mileage license to audit a mileage basis. You need consistency, and you get at it three ways.
Compare the carrier’s number to itself. Pull twelve invoices on the same origin and destination pair from the same carrier. If the billed miles are identical every time, the carrier is rating off a stored lane distance, which is normal and easy to check once. If the miles vary load to load, ask why. Legitimate reasons exist: a different delivery address inside the same city, a stop-off, an out-of-route detour the shipper requested. Illegitimate ones exist too, including a rating engine that recalculates at billing time using street addresses while the rate was quoted on ZIP codes.
Compare across carriers on the same lane. Two carriers hauling the same origin to the same destination should be within a small band of each other. One carrier consistently billing several percent more miles than its peers on identical lanes is running a different setting. This comparison costs you nothing and it points precisely at whom to ask.
Compare to the rate quote. The miles used to build the rate and the miles used to bill the load should be the same miles. When a broker quotes off one engine and the carrier bills off another, the gap is margin moving in whichever direction the engines disagree. That is the same class of problem as any other mismatch between the rate confirmation and the carrier invoice, and it is worked the same way: field by field, against the document that priced the load.
Then ask the carrier directly. The request is short and entirely reasonable: which engine, which routing type, which version, and city-to-city, ZIP-to-ZIP or address-to-address. A carrier that cannot answer is telling you the number is not derived from a stated method, which is itself the finding.
You also have a modest regulatory foothold. Under 49 CFR 373.103, a freight or expense bill must show origin and destination, the exact rates assessed, the total charges due with the nature and amount of each charge, and the route and each participating carrier. That does not entitle you to a mileage methodology, and do not claim it does. It does mean a bill that prints a per-mile rate and a total but never states the miles is thin, and asking for the mileage the rate was applied to is a fair request under it.
Stop-offs, out-of-route and the miles that genuinely changed
Not every mileage variance is an error, and treating it as one costs you credibility with a carrier you need.
Stop-offs. A load with an intermediate pickup or delivery is longer than the direct lane. The extra miles are real. What to check is that the stop-off charge and the extra miles are not both billing you for the same thing twice, and that the fuel surcharge is being applied to the added miles rather than to the flat stop fee. Whether fuel should touch that flat fee at all is its own question, covered in whether your fuel surcharge is being applied to accessorials it should not touch.
Out-of-route miles. A detour for a road closure, a weight restriction, or a receiver’s routing instruction adds real distance. If the carrier is billing it, ask for the reason and the segment. Reasonable carriers will produce it.
Deadhead. Miles run empty to reach the pickup are the carrier’s cost of positioning, not transportation of your freight, and they are only billable if the agreement says so. If a per-mile bill includes deadhead, that is a contract term to look at, not an arithmetic error.
The discipline is the same in all three cases: separate the question “were these miles driven” from the question “does the contract make them billable to me.” They have different answers and different remedies.
The contract language that ends the argument
One sentence in the transportation agreement removes this entire category. Name all four variables.
Mileage for rating linehaul and fuel surcharge shall be determined using PC Miler version [X], Practical routing, calculated ZIP code to ZIP code, with no toll-avoidance option applied. The same mileage figure shall be used for the linehaul rate and for the fuel surcharge on each shipment.
The second sentence does more work than the first. It forecloses the split-basis case, where a carrier rates linehaul on practical miles and fuel on a different figure, which is nearly impossible to spot on an invoice and trivially prevented in a contract.
A few notes on filling in the blanks. Practical routing is the sensible default: it is what the truck drives, and demanding shortest miles is asking a carrier to be paid for distance it cannot legally or safely run. Pin the version, and agree in advance how a version update is handled at renewal rather than mid-term. And specify ZIP-to-ZIP unless your facilities are far enough off the centroid that address-level matters, in which case say so.
Getting this into the agreement is a negotiation, and it belongs in the same conversation as the peg, the MPG and the surcharge cap. Which of those levers actually move, and which are fixed by the published index, is laid out in what is actually negotiable in a fuel surcharge.
If you are the shipper
Your leverage is at contract time, and your evidence is the invoice history. Before the next rate cycle, pull your top ten lanes by volume, tabulate billed miles by carrier, and find the lanes where one carrier is consistently above the others. That table is the entire negotiation. You are not accusing anyone of anything; you are asking every carrier to rate on the same stated basis, which is a request none of them can reasonably refuse.
On individual invoices, apply a threshold. A two-mile variance is not worth an email. A consistent variance on a weekly lane is worth a conversation, because the recovery is annualized rather than per load.
If you are the broker
You carry the mileage risk on both sides. You quoted the customer on one number and you agreed to pay the carrier on another, and if the two came from different engines or different routing types, the gap lands in your margin without ever appearing as a dispute.
Two habits fix most of it. First, use one engine and one configuration for every quote and every rate confirmation you issue, and state the miles on the rate con so there is a number to reconcile against. Second, when a carrier invoice comes in with different miles than the rate con, treat it as a settlement exception rather than a rounding tolerance, because a carrier that bills long on one lane is billing long on all of them.
There is also a customer-facing version of this. If you bill your customer on shortest miles and pay your carrier on practical miles, you are structurally short on every load in that lane, and no amount of settlement discipline recovers it. That is a pricing decision to make consciously, not an error to catch later.
The checklist
- Find the mileage clause in the contract. Note which of the four variables it actually specifies: engine, routing type, version, address resolution.
- Pull the billed miles from ten invoices on your highest-volume lane. Are they constant or do they vary?
- Compare billed miles across carriers on the same lane. Flag any carrier consistently above the group.
- Compare billed miles to the miles on the rate confirmation or the quote.
- Confirm the same mileage figure was used for linehaul and for fuel. Divide the fuel line by the per-mile surcharge and see whether the quotient equals the billed miles.
- Ask the carrier for engine, routing type, version and address resolution in writing. Keep the answer with the contract file.
- Verify separately that the surcharge per mile itself is right, which means checking which DOE week applies to the shipment, because a wrong week and a wrong mileage basis are independent errors.
- At renewal, write all four variables and the same-figure requirement into the agreement.
Step five is the one that catches the split basis, and it takes ten seconds. If your surcharge is $0.4667 per mile and the fuel line reads $299.16, the carrier billed fuel on 641 miles. If the linehaul reads $1,240.00 at $2.00 per mile, it billed linehaul on 620. Same load, two mileage figures, and only the division reveals it.
Sources
- 49 CFR 373.103, Freight or expense bills (Cornell LII: a freight bill must show origin and destination, the exact rates assessed, the total charges with the nature and amount of each charge, and the route and participating carriers)
- 49 CFR 373.101, Motor carrier receipts and bills of lading (Cornell LII: required contents of the receipt or bill of lading, including origin and destination)
- 49 U.S.C. 13710, Information and records, billing and contesting windows (Cornell LII: 180 days to contest a bill, 180 days for a carrier to bill additional charges)
- EIA, On-Highway Diesel Fuel Price Survey procedures and methodology (the weekly published index behind the per-mile surcharge that the mileage figure multiplies)
- FreightWaves, Fuel surcharges in trucking (trade-press explainer on how per-mile surcharges are constructed)