Free heating oil tool
Heating Oil Tank Fill Calculator
Check how much oil your tank can safely take before you order 500 litres, 900 litres, or a full top-up.
Tank Fill Calculator
Estimate your safe order size from tank capacity and current level.
This is a planning estimate. Leave enough headroom for expansion and ask your supplier or OFTEC technician if your tank gauge is unreliable or the tank is unusually shaped.
Treating the oil? Check the additive payback first
Once you know your safe order size, estimate the additive dose, payback, and annual benefit for that fuel volume.
Why safe fill volume matters
Ordering too little can leave you paying another delivery charge sooner than planned. Ordering too much can create a failed delivery or an overfill risk. Use this tool alongside your tank gauge and supplier advice.
Best for order planning
Use it before comparing 500L, 900L, and 1000L quotes so you know which order sizes are realistic.
Check the tank guide
Oil tank rules, bunding, and siting can affect safe delivery, especially on older installations.
Tank fill FAQs
How much heating oil can I put in my tank?+
Subtract your current oil level from a safe maximum tank level, leaving headroom for expansion. The calculator estimates this from your tank capacity, current percentage, and chosen headroom allowance.
Should I fill my oil tank to 100 percent?+
Many households leave a small headroom allowance rather than planning to fill the tank to the absolute top. Ask your supplier or OFTEC technician if your gauge or tank shape makes the estimate uncertain.
What if my tank has less than 500 litres of room?+
Most standard tanker quotes are based around 500 litres or more. If your tank has less room than that, wait until there is safe capacity, ask a local supplier about specialist options, or check the 500 litre guide before ordering.