Know the Week the Oil Runs Out, Not the Morning It Does — Free
Off-grid heating runs out on a Tuesday in January, and the supplier's lead time in January is not the lead time in October. This tag takes the reading on the tank, your own burn rate and each supplier's quoted lead time, and works back to the date the order has to be placed — one row per fuel, sorted by which one runs out first.
The proof surface
Free path: the tag computes locally in the browser with no key and no account. Where an AI step helps, any free chat assistant works — Google AI Studio's free tier and Groq's free tier were both no-card and rate-limited when this page was reviewed on 2026-09-13 (limits change; check before you rely on them).
Why the flat version breaks
A dipstick reading is a number with no clock attached, and 'we are getting low' is a feeling that arrives too late. Dividing the same reading by the litres you actually burn a week turns it into days of cover, and subtracting the supplier's lead time turns that into an order date — which is the only figure that prevents an emergency delivery charge.
How to use the heating fuel dip tag in four passes
A dip reading or the gauge on the tank is a number; a remembered one is a hope. Write down what you actually measured, and note the date you measured it if it was not today.
Take a reading, wait a fortnight, take another, divide the difference by the weeks. Winter and shoulder-season rates are different numbers — use the one for the season you are ordering into.
Autumn lead times are not January lead times. An email saying 'three weeks in January' is the difference between an order date and an emergency delivery surcharge.
A delivery changes the on-hand figure and usually the lead time too. Update the row, reset today's date, and the tag hanging on the tank stays a live document instead of a souvenir.
SAMPLE DATA, NOT A VERIFIED CLAIM: Beck House, off-grid · 23 Nov 2026 · 420 L on hand · 145 L a week · Dales Fuel quoting 12 days · logs at 60 units and 22 a week from Sawyers of Ripon. Replace these values with your own source before you rely on anything.
What breaks first
Using a summer burn rate in December
A rate measured in October understates January by half. The order date moves with the season, and the tag can only use the number you give it.
Ignoring the sludge at the bottom of the tank
A tank reading of 420 litres does not mean 420 usable litres — most tanks have a bottom few centimetres the boiler should never draw. Subtract what your supplier told you is unusable.
Ordering the cheapest fuel on the day it runs out
An emergency delivery is priced like one. The whole point of the order-by date is that it is early enough to shop around and to wait for the price to move.
What you pay otherwise
| The usual route | What it leaves out | Cost |
|---|---|---|
| An emergency out-of-hours delivery | The same fuel, delivered at short notice | an urgent-delivery surcharge |
| A tank-monitoring device | A gauge that phones the supplier, and your consumption data with it | hardware plus a monitoring subscription |
| An electric fan heater as a stopgap | Runs while you wait for the delivery | a winter electricity bill at peak rate |
| This page + the free heating fuel dip tag | Computed in your tab, result on screen before you type anything | $0 |
Try the free heating fuel dip tag
Five fuels are already run against 23 Nov 2026, with the heating oil at 19 days of cover and a 12-day lead time putting the order date in the first week of December. Load the deep-winter record and the oil row goes past today.
Open the free heating fuel dip tag →Keep the work if you will use it again
Every fuel row, days of cover, the order-by dates and the past-date flags, plus copy and share-link, with no account.
The on-screen result is free and repeatable forever. The one-time tier adds a tangible file you keep and the saved history that comes with it; it never removes or degrades the free result.
Boundary: This does arithmetic on the readings and lead times you type in; it is not a tank measurement, it cannot verify a supplier's delivery times, and it does not account for unusable fuel at the bottom of a tank or for weather. Confirm quantities and lead times with your supplier in writing before you rely on a date.