Checked against the Marketing Discipline Guidelines 2024 (Ver. 1, effective 24.10.2024) on 26 October 2026. Published by MDG Services on 26 October 2026.
This is the density at 15°C calculator run the other way: from the density at 15°C to what the hydrometer shows.
What the hydrometer reads at each temperature
A helper only. The printed ASTM Table 53B, or the figure your oil company works out, decides.
How to read it
The hydrometer shows the density of the sample at the sample's own temperature. MDG compares density at 15°C MDG 1.2(iv), and the morning density you record is also the figure at 15°C MDG 1.4.1(c). So a reading taken warm is converted with the ASTM table, which every dealer must hold MDG 1.5(vi).
The table here goes the other way. If the invoice says 830.0 at 15°C and your sample is at 30°C, the hydrometer should read near 819.5. A reading far from that means look again at the hydrometer and the thermometer.
For example, with made-up densities at 15°C:
| Sample temperature | Diesel 830.0 | Petrol 747.5 |
|---|---|---|
| 10 °C | 833.5 | 751.9 |
| 15 °C | 830.0 | 747.5 |
| 20 °C | 826.5 | 743.1 |
| 25 °C | 823.0 | 738.6 |
| 30 °C | 819.5 | 734.2 |
| 35 °C | 816.0 | 729.7 |
| 40 °C | 812.5 | 725.2 |
| 45 °C | 808.9 | 720.7 |
Note: these are worked out by the tool, not copied from the ASTM table. The last digit can differ from the printed table, and the table decides.
The limits for a tanker check are on the invoice density check page, and why the same fuel reads differently by time of day is on density and temperature.
Questions dealers ask
01Diesel density at 30 deg C: what will the hydrometer read?
It depends on the density at 15°C. For example, a diesel of 830.0 kg/m³ at 15°C reads about 819.5 at 30°C and 812.5 at 40°C. Type your own density in the tool.
02Petrol density at 40 °C?
For example, a petrol of 747.5 kg/m³ at 15°C reads about 725.2 at 40°C. In these examples petrol loses more per °C than diesel does.
03Is there a diesel density chart with temperature in a PDF?
MDG prints none. It requires every dealer to hold the ASTM density conversion table MDG 1.5(vi) and names Table 53B for the tanker check MDG 1.2(iv). This tool works the values out for your density instead of copying a table.
04Why does the hydrometer read lower in hot weather?
Fuel expands as it warms, so the same fuel weighs less per litre. MDG compares density at 15°C MDG 1.2(iv), so a hot-day reading is converted before it is compared.
05At what temperature is the density recorded in the register?
At 15°C. The morning density from the pump nozzle MDG 1.4.1(c) and the density after each tanker MDG 1.2(xiv) are both recorded at 15°C.
06Is this table the final answer?
No. If it differs from the printed ASTM table, the table decides MDG 1.2(iv) MDG 1.5(vi). If your oil company gives another figure, ask which one to use.
Read the official text: Marketing Discipline Guidelines 2024 (PDF on Bharat Petroleum's website) (also published on iocl.com).
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