Calculator
Formula used
Specific gravity (SG) compares ammonia density to water density at a chosen reference:
SG = ρammonia / ρwater
If you enter SG directly (hydrometer), the calculator also returns ammonia density:
ρammonia = SG × ρwater
For Baumé conversions, the calculator uses common hydrometer relationships:
- SG = C / (C + °Bé) for liquids lighter than water
- SG = C / (C − °Bé) for liquids heavier than water
Choose the constant C to match your chart or standard.
How to use this calculator
- Select your calculation method (density, hydrometer SG, or Baumé).
- Enter the required reading and select the correct unit.
- Pick a water reference: temperature-based or custom density.
- Click Calculate to view results above the form.
- Use Download CSV or Download PDF for records.
Example data table (illustrative)
These examples show how SG changes with density using water near 20°C. Values are for demonstration only.
| Reference temp (°C) | Ammonia density (g/mL) | Water density used (kg/m³) | Specific gravity |
|---|---|---|---|
| 20 | 0.600 | 998.234 | 0.601062 |
| 20 | 0.650 | 998.234 | 0.651150 |
| 20 | 0.700 | 998.234 | 0.701239 |
| 20 | 0.800 | 998.234 | 0.801416 |
| 20 | 0.900 | 998.234 | 0.901593 |
1) What ammonia specific gravity represents
Specific gravity (SG) is a ratio: ammonia solution density divided by the density of water at a chosen reference. Because it is dimensionless, SG is handy for quick checks in plants, labs, and storage facilities. For many aqueous solutions, SG also tracks concentration trends, but it is not a direct percent conversion.
2) Why the water reference matters
Water density changes with temperature. Around 4 °C, water is close to 1000 kg/m³. Near 20 °C, water is roughly 998 kg/m³, so the same liquid density gives a slightly higher SG at 4 °C. This calculator lets you select a temperature-based reference or enter a custom water density.
3) Density input method and unit control
If you have a measured density from a datasheet or lab test, enter it in g/mL, kg/m³, or lb/ft³. The calculator converts your value to a common base, then computes SG with the selected water reference. This supports mixed unit workflows without manual conversions.
4) Hydrometer SG method for fast field checks
Many operators read SG directly from a hydrometer. Enter that reading to back-calculate the solution density. This is useful when you need density for inventory, pumping calculations, or reporting. Always note the hydrometer temperature correction rules used at your site.
5) Baumé scales and the two conversion paths
Some hydrometers show Baumé (°Bé) instead of SG. There are different relationships for liquids lighter than water versus heavier than water. This tool includes both options and lets you choose a common constant (145 or 140) so you can align results with your reference chart.
6) Temperature and concentration effects to expect
In general, warmer liquids expand and become less dense, which lowers SG when the water reference is held constant. Stronger aqueous ammonia solutions can show noticeably different SG values than dilute mixtures. Use measurements taken at a consistent temperature for better comparisons.
7) Practical data checkpoints
As a quick sanity check, if a solution density is 700 kg/m³ and water is 998 kg/m³ at 20 °C, SG ≈ 700/998 ≈ 0.701. If density rises to 900 kg/m³ at the same reference, SG ≈ 0.902. The example table on this page demonstrates similar calculations.
8) Reporting and record keeping
Operations often need a traceable value set: inputs, reference basis, and computed outputs. Use the built-in CSV download for spreadsheets, and the PDF report for audit trails or shift handovers. When sharing results, include the reference temperature or custom water density used.
1) Is specific gravity the same as density?
No. Density has units (kg/m³, g/mL). Specific gravity is a unitless ratio of the liquid’s density to the chosen water density reference.
2) Which reference temperature should I use?
Use the same reference as your lab method, datasheet, or plant standard. If your density is measured at 20 °C, using water at 20 °C keeps the comparison consistent.
3) Why do my SG values differ from a chart?
Differences usually come from temperature, hydrometer calibration, the Baumé constant used, or whether the chart assumes a specific reference basis (like water at 60 °F). Match the same assumptions.
4) Should I choose Baumé lighter or heavier?
Pick “lighter than water” when the liquid’s SG is below 1.0. Choose “heavier than water” when SG is above 1.0. If unsure, compare your reading to water.
5) Can I enter custom water density?
Yes. Select “Custom water density” and enter the value in kg/m³. This is helpful when your method references a different standard or you are correcting for non-ideal conditions.
6) Is this calculator for anhydrous ammonia or aqueous ammonia?
It works for either, as long as you supply a valid density, SG, or Baumé reading for your sample at the chosen reference. The tool does not assume concentration by itself.
7) What result should I store in logs?
Record SG, ammonia density, the water reference (temperature or custom density), and the input method used. That combination makes the value reproducible and easier to audit later.