When will my heating oil run out?
Gallons left, your ZIP code and how fast you have been burning it give the day you'll need to reorder and the day you'd run dry — using 30 years of NOAA weather normals for your area. Works for heating oil and propane.
Don't know the gallons? Read your stick or gauge on a tank chart — the 275 gallon oil tank chart covers the most common indoor tank — or use the heating oil tank calculator.
How the forecast works
use = HDD ÷ K + non-heating gallons per dayK = degree days between the readings ÷ gallons burned for heatA house burns fuel roughly in proportion to how cold it is outside, and heating degree days measure exactly that. Fuel dealers use this to schedule automatic deliveries: once they know a house's K-factor, the weather tells them when the tank will be low. This page does the same thing with the daily weather a typical year brings to your ZIP code — NOAA's 1991–2020 monthly heating-degree-day normals, spread evenly through each month.
What it can't know: this winter's actual weather, a thermostat change, a houseguest or a burner that needs servicing. A cold snap moves the run-out date earlier. Treat the reorder date as the planning figure and keep a margin; re-run it after each stick reading.
The weather station is the nearest NOAA normals station with a full heating-degree-day record to the Census Bureau's centre point for your ZIP code. In mountains or on the coast a station a few miles away can differ noticeably from your house; if your dealer gives you a K-factor, their figure already reflects your local weather.
FAQ
TVC-117/FAQHow long will my heating oil last?
Divide the heating degree days your area gets each day by your K-factor, add any oil you use for hot water, and divide that into the gallons left. The calculator above does it day by day with your ZIP code's normal weather, so a cold January uses oil faster than a mild November.
What is a K-factor?
The number of heating degree days it takes your house to burn one gallon. Fuel dealers on automatic delivery track it for every customer, and many print it on the delivery ticket or show it in the online account. A bigger K-factor means a more efficient house — each gallon lasts more degree days.
How do I work out my K-factor myself?
Use two readings: the gallons in the tank on an earlier date (a delivery that filled it is ideal) and the gallons now. The degree days in between divided by the gallons burned for heat is your K-factor. The calculator uses the 30-year normal degree days for that span, so the result is an estimate — over a full winter the errors largely cancel.
What is a heating degree day?
A measure of how cold a day was. Take 65 °F minus the day's average temperature: a day averaging 35 °F counts as 30 degree days; a day at 65 °F or warmer counts as zero. The US Energy Information Administration and NOAA use the same 65 °F base.
Does this work for propane?
Yes, for propane used for heating. Enter gallons, not the gauge percentage — or enter the tank's water capacity and the gauge % and the calculator converts it (a propane gauge reads percent of water capacity). Add your cooking, dryer and water-heater use as non-heating gallons per day.
When should I reorder?
Before the tank gets low enough to draw sediment into the line or leave you exposed to a delivery delay. The calculator defaults to a quarter of the tank; set your own level if your dealer gives one.
Sources and standards
- U.S. Climate Normals 1991–2020 — monthly heating degree days (MLY-HTDD-NORMAL, base 65 °F)NOAA National Centers for Environmental Informationhttps://www.ncei.noaa.gov/data/normals-monthly/1991-2020/Monthly normals for 7,226 US stations with a complete heating-degree-day record, downloaded 2026-11-01.
- 2023 Gazetteer Files — ZIP Code Tabulation Areas (internal point latitude and longitude)U.S. Census Bureauhttps://www.census.gov/geographies/reference-files/time-series/geo/gazetteer-files.htmlUsed to place each ZIP code; 33,634 ZCTAs matched to a station within 150 miles.
- Degree days — Energy ExplainedU.S. Energy Information Administrationhttps://www.eia.gov/energyexplained/units-and-calculators/degree-days.phpDefinition of heating degree days and the 65 °F base.
Every linked source above was retrieved and checked on 2026-11-01.