Free printable dip chart
A 2,500 litre oil tank holds about 2,508 litres full and roughly 2,132 litres at the 85% safe fill. A dip reading of 48cm on this horizontal cylinder tank is about 732 litres, or 29% full, so topping up to safe fill would mean ordering about 1,400 more litres.
The 2,500 litre tank is a large capacity for bigger properties and small businesses. It is often a lying-down cylinder, so its dip chart is genuinely non-linear: a quarter of the depth is well under a quarter of the oil.
This tank holds about 2,508 litres full, with a 85% safe fill near 2,132 litres. A dip reading of 48cm works out at roughly 732 litres, or 29% full. Topping up to safe fill from there is about 1,400 litres. Enter your own price per litre in the calculator above to turn that into a cost.
Every 5cm of oil depth for the 2,500 litre oil tank. Print this and keep it by the tank.
| Depth (cm) | Litres | % full |
|---|---|---|
| 5 | 27 | 1% |
| 10 | 76 | 3% |
| 15 | 139 | 6% |
| 20 | 211 | 8% |
| 25 | 291 | 12% |
| 30 | 379 | 15% |
| 35 | 471 | 19% |
| 40 | 568 | 23% |
| 45 | 670 | 27% |
| 50 | 774 | 31% |
| 55 | 881 | 35% |
| 60 | 989 | 39% |
| 65 | 1,099 | 44% |
| 70 | 1,210 | 48% |
| 75 | 1,321 | 53% |
| 80 | 1,431 | 57% |
| 85 | 1,541 | 61% |
| 90 | 1,649 | 66% |
| 95 | 1,755 | 70% |
| 100 | 1,859 | 74% |
| 105 | 1,959 | 78% |
| 110 | 2,056 | 82% |
| 115 | 2,147 | 86% |
| 120 | 2,233 | 89% |
| 125 | 2,312 | 92% |
| 130 | 2,383 | 95% |
| 135 | 2,443 | 97% |
| 140 | 2,488 | 99% |
| 144 | 2,508 | 100% |
Horizontal cylinder (circular segment, non-linear with depth): segment_area = r^2 x acos((r - h) / r) - (r - h) x sqrt(2 x r x h - h^2) litres = segment_area x length / 1000 This tank: radius 72cm, length 154cm capacity = 2508 litres safe fill = 2508 x 0.85 = 2132 litres Example: depth 48cm -> 732 litres (29% full)
| Figure | Value | Source | Verified |
|---|---|---|---|
| tank safe fill pct | 0.85 ratio | OFTEC guidance: tanks are filled to 80-90% of stated capacity to allow expansion | 2026-07-28 |
| vat domestic | 0.05 ratio | VAT Act 1994 Schedule 7A Group 1, domestic fuel reduced rate | 2026-07-28 |
Make and exact dimensions. The figures here are for representative internal dimensions of a 2,500 litre oil tank. Different makes vary by a few centimetres, so if your dip reading seems out of step, measure your own tank and use the custom builder.
Shape. This is a lying-down cylinder, so litres lag depth in the lower third and catch up around the middle. Use the chart, not a straight-line guess.
Safe fill. Order to the 85% figure of about 2,132 litres rather than the brim, so the oil has room to expand and the vent does not overflow during delivery.
Reading conditions. Keep the rod vertical and resting on the base, and allow for a little sludge at the bottom of an older tank. Treat the very lowest readings as a warning to reorder rather than a precise measure.
Read your tank and know roughly how much to order? Compare quotes from local suppliers and top up before you run low.
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