Know which tanks to fill this week, from live degree days
Tankfern forecasts each customer tank from its K-factor and live NOAA heating degree days: gallons used since the last fill, % full today, the run-out date and the date to deliver by. It sorts the tanks that need a truck this week into a printable route sheet and shows EIA weekly heating-oil and propane prices beside them. Customer data stays on your device.
How a K-factor forecast works (illustrative tank, formula as Tankfern uses it)
| Input or step | Value |
|---|---|
| Tank size | 275 gal |
| Filled to | 250 gal |
| K-factor (degree days per gallon) | 6.0 |
| Heating degree days since the fill | 420 |
| Gallons used = degree days ÷ K | 70 gal |
| Left in the tank | 180 gal (65% full) |
| Deliver before it falls below | 25% (68.75 gal) |
Source: Illustrative numbers chosen for this example; the degree days in the app come live from NOAA for your weather station.
Tankfern vs the alternatives
Published prices, each checked on the date shown; prices change, so confirm on each site.
| Product | Price | Free | Checked |
|---|---|---|---|
| Tankfern Pro | $29/month, $290/year or $449 lifetime | 10 tanks, 1 weather station | live |
| Degree Days Online | $119.95/month for most companies (vendor page) | free trial | 2026-10-09 |
| Degree Days Online (Basic, TrustRadius) | from $79.95/month | free trial | 2026-10-09 |
| DegreeDays.net API | $9/month 1 location; $19 3; $29 6; $39 10 locations; $49-$1,995 rate-limited plans (data only) | free website lookups | 2026-10-09 |
| Droplet Fuel | price on request (full back office) | 2026-10-09 |
Why teams pick Tankfern
- Live NOAA heating degree days, no manual weather entry.
- K-factor forecasts per tank: gallons used, % full, run-out and deliver-by dates.
- A printable route sheet of the tanks due this week.
- A planner at a quarter of the price of the leading degree-day software.
How it works
- Pick your nearest weather station and add tanks with size, K-factor and last fill.
- Tankfern reads the degree days since each fill and forecasts every tank.
- Print the route sheet of tanks due this week.
FAQ
What is a K-factor?
The number of heating degree days it takes a home to burn one gallon. Type in the one you use, or let Tankfern Pro learn it from the tank's past fill-ups: K = degree days between deliveries ÷ (gallons delivered − fixed load).
Why not a full dispatch system?
Full back offices do billing, dispatch, trucks and payments, and are quoted on request. Tankfern is the lightweight planner for dealers who do not need all that: free for up to 10 tanks and $29 a month for unlimited.
Where is my data stored?
In your browser on your device. Tankfern's server never receives customer names, tanks or deliveries; it only passes public NOAA degree days and EIA prices through a cache.
Is this a safety device?
No. Tankfern gives planning estimates only. Always check the tank gauge.