Fuel
Calculate Fuel Savings
See what a truck or trailer change, a driving change, or a generator does to your diesel bill — and what those savings are worth if you invest them.
Saved on this device until you clear the browser. Numbers only — not advice.
FSC, spot, and base
6.0 MPG · $1.25 baseFSC
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per mile
Spot
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van 7-day avg
Base
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Rate − FSC
Loading this week's diesel…
Looking up 7-day avg…
On 110,000 miles this year: FSC —
If a load's FSC is below this, the rest is coming out of linehaul.
Modification
Break-even
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This year
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Waiting on this week's diesel
Year-one net
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After the shop bill
A month
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3-year net
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5-year net
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This year · MPG change
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Waiting on this week's diesel.
| Now | After | |
|---|---|---|
| Year's fuel bill | — | — |
| Gallons | 14,865 | 14,103 |
| Fuel ¢/mile | — | — |
| Saved vs now | — | — |
| A month | — | — |
| Break-even | — | — |
| Year-one net | — | — |
| 3-year net | — | — |
| 5-year net | — | — |
Speed vs fuel
Aero drag rises with speed squared. Same miles, same truck. Uses the current MPG and diesel price above.
Waiting on this week's diesel.
This year · slower or faster
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Waiting on this week's diesel.
After MPG
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A month
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Extra hours
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Same miles this year
Each mph
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Saved by slowing 1 mph
Idle vs generator
Idle the engine, or run a generator
Compare idling the truck to an ICE generator or an e-generator. Uses the diesel price from above.
Waiting on this week's diesel.
Invest the savings
MPG change plus generator
Waiting on this week's diesel.
Which generator to include:
Default 10% is a long-run S&P number, not a promise. You invest 100% of the combined savings ($2,935 this year).
5 years
$17,918
vs $14,674 in a checking account
10 years
$46,774
vs $29,349 in a checking account
20 years
$168,094
vs $58,697 in a checking account
Ten years: $46,774 if you invest 100% of the combined savings at 10%. That is $17,425 more than leaving the same amount in a checking account.
How we calculate
- Gallons this year = annual miles ÷ MPG.
- Dollars saved = gallons you do not buy × diesel price.
- Fuel ¢/mile = diesel ÷ MPG.
- FSC that should apply = (diesel − $1.25) ÷ 6.0 MPG. That is the standard table, not your truck's MPG. Floor at $0 when diesel is at or below $1.25.
- 7-day national linehaul comes from the latest van, reefer, and flatbed reports (minus fuel). Spot all-in = that linehaul + the FSC on this page. Base = Rate − FSC.
- State diesel is the AAA daily average by state. State tax is the IFTA special diesel rate, not the federal 24.4¢. Net = pump − state tax.
- Diesel starts as the EIA U.S. on-highway weekly average. Type your pump price if you want.
- Speed uses a Class 8 cruise split at 65 mph: about 50% aero, 42% rolling and drivetrain, 8% accessories. Aero energy per mile rises with speed squared. We scale that curve to the MPG you type at the speed you run now. Same miles at a lower speed take more hours.
- Idle cost = parked hours × gallons per hour × diesel. The generator uses the same hours at a lower burn.
- Invest uses the yearly dollar amount you choose to park, compounded at the rate you type. That rate is not a promise.