The desk runs six modes. They share one set of constants, so a figure produced in one mode and a figure quoted in prose on another page cannot disagree. Where a mode uses a model assumption rather than a measured value, the assumption is named on the screen and is editable.
What each mode does
| Mode | What you put in | What comes out | Where the worked example lives |
|---|---|---|---|
| Fill cost | Tank size, gauge reading, unit price | Litres or gallons deliverable and the money | /uk/tank-sizes-and-ullage |
| Order now or wait | Quantity, weeks, expected move, burn rate | Cost delta, break-even move, run-out date | /uk/order-now-or-wait |
| Plan compare | Season volume, cap price, cap fee, pre-buy terms | Cost under five plan types and the break-even price | /us/pre-buy-vs-cap-price-vs-budget-plan |
| Annual burn | Floor area, insulation band, boiler efficiency | Season litres or gallons and annual spend | /uk/annual-usage-and-cost |
| Fuel switch | Prices for oil, propane, gas and electricity, plus COP | Cost per useful kilowatt hour and per million Btu | /us/heating-oil-vs-heat-pump |
| Blend adjuster | Headline price per gallon and blend level | True cost per million Btu after the energy correction | /us/biodiesel-blend-cost |
Six named scenarios, with the maths shown
Each of these is a real decision someone is making this week. The numbers below come from the same functions the calculator runs.
| Scenario | Inputs | Output | Read it on |
|---|---|---|---|
| The October top-up | 1,200 litres, Suffolk, tank at a third | GBP 1,080.12 for the full 1,200 | /uk/1000-litre-cost |
| The cold-snap refill | 150 gallons, Connecticut, will-call | $830.25 at the last state print | /us/150-gallon-delivery-cost |
| The pre-buy gamble | 800 gallons locked in August | Break-even against the season average | /us/pre-buy-vs-cap-price-vs-budget-plan |
| The cap-price winter | 900 gallons, cap plus fee | Fee paid whether or not the cap bites | /us/pre-buy-vs-cap-price-vs-budget-plan |
| The heat-pump switch | Solid wall cottage, 19 year old boiler | 9.57p a useful kWh on oil | /uk/heat-pump-vs-oil-boiler |
| The B20 correction | Same dollars, less heat in the gallon | True cost per million Btu after the blend | /us/biodiesel-blend-cost |
What the desk will not do
- It will not ask for a postcode, a ZIP or an email address. There is no lead form on this site and no supplier is paying for placement.
- It will not quote you a supplier price. It applies a published reading, or a number you type in, to your own volume.
- It will not forecast. The order now or wait mode takes an expected move from you and shows what that assumption is worth. It does not supply the assumption.
- It will not hide an assumption. Boiler efficiency, coefficient of performance and demand per square metre are all on screen and all editable.
Primary sources for this page
- EIA State Heating Oil and Propane ProgramWeekly residential delivered price of No. 2 heating oil, national and by state. Collected October to March. The survey pauses after the last March print and resumes in October, which is why every federal page shows March data all summer.
- DESNZ Quarterly Energy Prices, table 4.1.1Monthly typical retail price of standard grade burning oil, the fuel sold to UK households as kerosene. Priced on the Monday nearest the 15th of the month, for deliveries of up to 1,000 litres, VAT at 5% included. This is the only official UK-wide domestic heating oil price series.
- Approved Document J, combustion appliances and fuel storage systemsThe building regulations guidance covering domestic oil tank installation and siting in England.
- NOAA heating degree daysThe degree-day basis for the annual burn model on this site.
- Alternative Fuels Data Center, biodiesel blendsEnergy content and blend handling guidance for B5 through B100.