How to Estimate Delivered Fuel Use From a Run of Tickets

Why this matters

A propane or oil customer has no monthly meter read. What they have is a stack of delivery tickets at irregular dates, some full fills, some not, and a feeling that "the new furnace burns more." A single ticket says almost nothing: a big delivery may just mean the truck stayed away longer. A whole season of tickets, lined up properly, says a great deal. It gives gallons per day, gallons per degree day, the house's base use, and a fair comparison of one winter against another. The work is mostly bookkeeping, and the two places it goes wrong are a partial fill read as use and a winter compared without its weather.

What the tickets carry, and what they do not

Each ticket gives the date and the gallons from the truck's meter, which is the certified measurement. Many also give the tank gauge before and after, which is an estimate from a float gauge, and some give degree days since the last delivery. Propane and Heating Oil Bills: When the Fuel Arrives by Truck reads a single ticket line by line; this card works the run.

Two facts about tanks that the arithmetic depends on:

• A propane tank's gauge reads percent of the tank's water capacity, and a fill stops near 80 percent. Propane expands as it warms, so the tank keeps vapor space. On a 500 gallon tank, each gauge point is 5 gallons, and the most it will take is about 400 gallons from near-empty. A ticket claiming a 430 gallon delivery into a 500 gallon tank is a ticket error or a second tank, not use.
• The gauge is coarse. A float gauge moves a few points with temperature and with the float's own slop. Trust the truck meter for gallons and use the gauge only where you must reconstruct a partial fill.

Step 1: Line the tickets up in date order and mark every fill

Get every ticket for at least two heating seasons and the summer between, from the customer or from the dealer's account history (most dealers will print a delivery history on request). Put them in a log with date, gauge before, gallons, gauge after, and days since the previous delivery. Mark each delivery that ended at the fill level (about 80 percent on propane, the whistle on most oil tanks) and each that did not.

Why: use is only measurable between two deliveries that left the tank at the same level. A fill replaces exactly what was burned since the last fill. A partial delivery replaces some unknown fraction of it.

What breaks if you skip it: a customer who asked for 100 gallons in a tight month shows up as a low-use interval followed by a huge one, and the huge one gets blamed on whatever changed that month.

Step 2: Fold every partial fill into the next full one

Treat the partial delivery's gallons as part of the next full-fill interval, and measure that interval from the fill before the partial to the fill after it. The tank started and ended at the same level, so the sum of every delivery inside the interval is exactly what was burned.

If you need the split inside that interval (to see a cold snap, say), reconstruct each piece from the gauge: gauge points used times gallons per point. Then check the pieces add to the deliveries. If they disagree by more than a few gauge points, trust the sum and let the split go.

Step 3: Get the base use from a summer interval

Most delivered-fuel houses also burn the fuel for something other than space heat: a water heater, a range, a dryer, a fireplace. That base use runs every day regardless of weather, and it has to come out before the heating figure means anything. The cleanest source is the summer interval between the spring fill and the autumn fill. Remove the small heating share from that interval's few degree days, then divide by its days.

What breaks if you skip it: gallons per degree day rises in mild intervals and falls in cold ones for no reason except that the base use is a bigger share of a mild month. It makes the shoulder months look like a problem and blurs any winter-to-winter comparison.

Base use in winter runs somewhat above summer base use (colder incoming water means more water heating), so a summer figure slightly understates it. Applied the same way to both winters, the error mostly cancels in the comparison; say so rather than correcting it.

Step 4: Add the degree days for each interval

Heating degree days (HDD) measure how cold a period was: each day contributes the amount its average temperature fell below a base, commonly 65 F. Pull them for the exact ticket dates from the nearest weather station. How to Weather-Normalize Two Winters of Bills covers where to get them and the base temperature question; this card only uses them.

Step 5: Compute gallons per day and heating gallons per degree day

For each fill-to-fill interval, and for each season as a whole:

• Gallons per day = gallons / days. Fine for "how fast is the tank going down," useless for comparing winters.
• Heating gallons per degree day = (gallons minus base use x days) / HDD. This is the house's own figure, and it should hold fairly steady interval to interval if nothing changed.

The worked log

A propane customer, 500 gallon tank, propane furnace plus a propane water heater and range. A new furnace was installed in October 2025, and the customer believes the winter of 2025-26 used far more fuel than 2024-25.

DATE        BEFORE  GALLONS  AFTER  DAYS  HDD
10/15/2024  -       -        80%    -     -     start
12/03/2024  50%     150      80%    49    700
01/14/2025  33%     236      80%    42    1,250
02/25/2025  28%     260      80%    42    1,400
04/10/2025  39%     204      80%    44    1,050
10/20/2025  49%     155      80%    193   120   summer
12/01/2025  50%     148      80%    42    780
01/09/2026  31%     100      51%    39    1,420 PARTIAL
01/30/2026  23%     284      80%    21    830
03/06/2026  39%     204      80%    35    1,180
04/15/2026  48%     159      80%    40    860

Gauge against truck. The 12/03/2024 fill moved the gauge 30 points, 150 gallons at 5 per point, matching the ticket exactly. Most rows agree within a point.

The partial fill. On 01/09/2026 the customer asked for 100 gallons and the tank stopped at 51 percent, not 80. That interval (12/01 to 01/09) is not use. Folded into the next fill, 12/01/2025 to 01/30/2026 is one 60-day interval (39 + 21) with 1,420 + 830 = 2,250 HDD and 100 + 284 = 384 gallons burned. The gauge reconstruction agrees: 80 minus 31 is 49 points, 245 gallons, before the partial, and 51 minus 23 is 28 points, 140 gallons, after it, for 385 against the tickets' 384.

Base use. The summer interval took 155 gallons in 193 days with 120 HDD. Using last winter's heating figure (worked below) for the 120 HDD, the heating share is 0.165 x 120 = 19.8 gallons. That borrows a figure that itself depends on the base use, but the share is small enough that a second pass moves nothing past the first decimal. That leaves 155 minus 19.8 = 135.2 gallons of base use, or 135.2 / 193 = 0.70 gallons a day.

Winter 2024-25, 10/15 to 04/10. 177 days, 700 + 1,250 + 1,400 + 1,050 = 4,400 HDD, 150 + 236 + 260 + 204 = 850 gallons. Base use is 0.70 x 177 = 123.9 gallons, leaving 726.1 heating gallons, or 726.1 / 4,400 = 0.165 gallons per HDD. Interval by interval, the heating figure holds still: (150 minus 0.70 x 49) / 700 = 0.165, and the coldest interval gives (260 minus 29.4) / 1,400 = 0.165 too. Raw gallons per HDD without the base use taken out would have run from 0.214 in the first interval to 0.186 in the coldest, a drift that is all base use.

Winter 2025-26, 10/20 to 04/15. 177 days, 780 + 2,250 + 1,180 + 860 = 5,070 HDD, 148 + 100 + 284 + 204 + 159 = 895 gallons. Less 123.9 gallons of base use leaves 771.1 heating gallons, or 771.1 / 5,070 = 0.152 gallons per HDD.

Reading the two winters against each other

What the customer saw. 895 gallons against 850 is 5.3 percent more fuel, and two deliveries in January (one of them the partial) made it feel like much more than that. Gallons per day rose from 850 / 177 = 4.80 to 895 / 177 = 5.06.

What the weather did. 5,070 HDD against 4,400 is 15.2 percent colder. A house that changed nothing would have needed about 15 percent more heating fuel, not 5.

What the house did. Heating gallons per HDD fell from 0.165 to 0.152: 0.152 / 0.165 = 0.92, so about 8 percent less fuel per unit of cold after the new furnace. That is the figure the customer's question was actually about, and it runs the opposite way to their impression.

How firm is it. Two seasons, one station, a summer base use applied to both winters: firm enough to say "the new furnace is not using more, and the weather explains last winter," not firm enough to quote 8 percent as the furnace's savings. Comparing seasons in this way is the reason to collect the tickets; promising a number from it is not. See related: Savings Claims Without Overpromising: The Honest Language.

Where the run of tickets misleads

• A ticket with no gauge readings and no "fill" note. You cannot tell a fill from a partial. Ask the dealer; their records usually show whether the driver filled to the stop.
• A mid-season tank swap or a second tank. A new tank on the account restarts the level and breaks the interval. So does a tank set at a second building on the same account.
• An autumn fill that is late or early. If the start-of-season fill lands in the middle of a cold spell, its interval borrows heat from the season before. Compare seasons that start and end on similar dates, as both of these did (177 days each), or compare per degree day, which tolerates uneven dates.
• An out-of-gas event. A tank run dry needs a leak check before the system is relit, and the delivery that follows is a fill from empty that no prior gauge reading describes. NFPA 58, in the edition your state has adopted, calls for a leak check before an interrupted system goes back into service; the dealer normally performs it, and state rules on who else may vary. Do not relight anything yourself.
• Use that changed for another reason. A new hot tub, a guest who stayed the winter, a garage heater that was off last year. The per-degree-day figure rises with any of them, and the tickets cannot say which. See related: The Loads a Customer Forgets They Own.

What you hand the customer

A short note with the two seasons side by side: gallons, HDD, heating gallons per HDD, and one sentence on what the comparison means. Name the weather station and the base use you assumed. A customer who can see the 15 percent colder winter next to the 5 percent more fuel rarely needs the arithmetic explained twice.

References

• See related: How to Weather-Normalize Two Winters of Bills
• See related: Propane and Heating Oil Bills: When the Fuel Arrives by Truck
• See related: How to Estimate Oil Use From Nozzle Size and Burner Run Time
• NFPA 58, Liquefied Petroleum Gas Code, in the edition adopted by your state, which sets container filling limits and the dealer's leak check after a supply interruption