Glycerin Density Calculator: g/mL by Temperature

This calculator works out the density of glycerin (glycerol) at a given temperature, returning the value in grams per milliliter (g/mL). You enter the temperature in degrees Celsius, and you get back the density corrected for thermal expansion, plus the density in kilograms per cubic meter (kg/m³) for engineering work.

Formula

The density of pure glycerin (C₃H₈O₃) decreases as temperature rises because the liquid expands. The standard reference value is at 20 °C, where glycerin has a density of approximately 1.261 g/mL. The calculator uses a quadratic fit to published density data over the range of about -50 °C to 150 °C:

�(t) = 1.26108 − 0.000615·t − 0.0000004·t²

Where:

• Ï� = density in g/mL (same as g/cm³)
• t = temperature in °C
• 1.26108 = density at 0 °C in g/mL (the intercept)
• −0.000615 = linear thermal expansion coefficient term (g/mL per °C)
• −0.0000004 = quadratic correction term (g/mL per °C²)

The quadratic term is small but improves accuracy at temperature extremes. At 20 °C, the formula gives 1.26108 − 0.0123 − 0.00016 = 1.2486 g/mL, which is very close to the commonly cited value of 1.249 g/mL at 20 °C. The slight difference (about 0.0004 g/mL) is within the variation seen between different commercial grades of glycerin.

Worked Example

Using the default values from the calculator: temperature = 20 °C.

1. Start with the formula: � = 1.26108 − 0.000615 × 20 − 0.0000004 × 20²
2. Calculate the linear term: 0.000615 × 20 = 0.0123
3. Calculate the quadratic term: 20² = 400; 0.0000004 × 400 = 0.00016
4. Subtract both from the intercept: 1.26108 − 0.0123 − 0.00016 = 1.24862
5. Round to three decimal places: 1.249 g/mL

For kg/m³: 1.24862 × 1000 = 1248.6 kg/m³. This matches the calculator output.

Why Glycerin Density Matters

Glycerin is a viscous, hygroscopic liquid used in pharmaceuticals, cosmetics, food (as E422), antifreeze formulations, and as a humectant in e-liquids and soaps. Density measurements are essential for quality control, for converting between mass and volume in recipes, and for blending with water or other solvents. Unlike water, which has its maximum density at 4 °C, glycerin simply becomes denser as it cools, with no anomaly. This makes the temperature correction relatively straightforward.

One important consideration: the density of glycerin depends heavily on purity. Pure anhydrous glycerin (99.5% or higher) has a density of about 1.261 g/mL at 20 °C. If the glycerin contains even 5% water, the density drops noticeably to around 1.247 g/mL. The calculator assumes pure glycerin; for diluted solutions, you need a different correlation that accounts for water content.

How to Use the Result

Once you have the density, you can convert between mass and volume using the relationship:

mass (g) = density (g/mL) × volume (mL)

For example, if you need 500 mL of glycerin at 20 °C, the mass is 1.249 × 500 = 624.5 grams. Conversely, if you weigh out 1 kg of glycerin at 40 °C (density ≈ 1.235 g/mL), its volume is 1000 ÷ 1.235 ≈ 810 mL.

In industrial settings, glycerin is often sold by weight but dispensed by volume, so density corrections prevent costly errors. In laboratory work, density is used to verify concentration or to calibrate viscometers, since viscosity measurements require accurate density values.

Temperature Range and Limits

The formula is valid for liquid glycerin from its melting point (about 17.8 °C for pure anhydrous glycerin, though it supercools easily and can remain liquid well below that) up to its boiling point (290 °C at atmospheric pressure). However, the quadratic fit is most accurate between −20 °C and 100 °C. Above 150 °C, glycerin begins to decompose slowly, and below −50 °C, the supercooled liquid becomes extremely viscous, making density measurements difficult and the fit less reliable.

Pure glycerin is notorious for supercooling: it can remain a liquid at −40 °C if cooled carefully, but the viscosity becomes so high it behaves like a glass. The density values from the formula still apply to this supercooled state, but handling such material is impractical for most users.

Common Mistakes and Unit Confusion

The most frequent error is confusing g/mL with kg/m³. A density of 1.249 g/mL equals 1249 kg/m³, not 1.249 kg/m³. The factor is 1000, not 1. Another common mistake is using the density of water (1.0 g/mL) as a substitute for glycerin, which underestimates mass by about 25% — a serious error in formulations.

Temperature units also cause problems. The formula requires Celsius. If you have a temperature in Fahrenheit, convert first: °C = (°F − 32) × 5/9. For example, 68 °F = 20 °C. Using 68 directly in the formula would give 1.219 g/mL, which is wrong by about 0.03 g/mL.

Finally, remember that glycerin absorbs water from the air. An open container of glycerin left in a humid environment will slowly become more dilute, lowering its density. Always measure density on a freshly opened or sealed sample for accurate results.

Comparison with Other Liquids

Glycerin is one of the densest common organic liquids. For comparison at 20 °C:

• Water: 0.998 g/mL
• Ethanol: 0.789 g/mL
• Propylene glycol: 1.036 g/mL
• Olive oil: 0.91 g/mL
• Honey (variable): 1.36–1.45 g/mL
• Mercury: 13.53 g/mL

Glycerin’s high density and high viscosity (about 1410 mPa·s at 20 °C, roughly 1400 times that of water) make it useful in applications where a heavy, stable liquid is needed, such as in hydraulic fluids, damping devices, and as a base for certain lubricants.

Safety and Handling Notes

Glycerin is generally recognized as safe (GRAS) by food authorities and is non-toxic. However, it is hygroscopic, meaning it draws moisture from the skin, which can cause irritation with prolonged contact. It is also a mild skin irritant for some people. In case of contact, rinse with water. Glycerin is not flammable at room temperature (flash point around 160 °C), but it will burn if heated sufficiently. Always store glycerin in a sealed container to prevent water absorption and contamination.

When heating glycerin, do so slowly and with adequate ventilation. Above 200 °C, it can produce acrolein, a pungent and irritating compound. Never heat glycerin in an open flame without proper fume extraction.

Frequently Asked Questions

Why does glycerin density change with temperature?
Like most liquids, glycerin expands when heated and contracts when cooled. The same mass occupies a larger volume at higher temperatures, so density (mass per volume) decreases. The change is roughly linear: about 0.06% per °C near room temperature.

What is the density of glycerin at 25 °C?
Using the formula: 1.26108 − 0.000615 × 25 − 0.0000004 × 625 = 1.26108 − 0.015375 − 0.00025 = 1.2455 g/mL, rounded to 1.245 g/mL. This is the value commonly used in room-temperature laboratory work.

Is glycerin heavier than water?
Yes, by about 25%. Pure glycerin has a density of about 1.249 g/mL at 20 °C, while water is 0.998 g/mL. This is why glycerin sinks in water and why mixtures of glycerin and water have densities between the two.

How do I convert glycerin density from g/mL to pounds per gallon?
Multiply by 8.345 (the number of pounds per gallon of water). For example, 1.249 g/mL × 8.345 = 10.42 lb/gal. This conversion is useful for shipping and industrial handling in the United States.

Does the density of glycerin change if it absorbs water?
Yes, significantly. A 10% water solution has a density of about 1.225 g/mL at 20 °C, and a 50% solution drops to about 1.126 g/mL. If your glycerin has been exposed to humid air, the density will be lower than the pure value. For precise work, measure the actual density with a hydrometer or pycnometer rather than relying on the pure-glycerin formula.

What is the difference between glycerin and glycerol?
None chemically — they are the same compound (propane-1,2,3-triol). In practice, “glycerol” is the chemical name for the pure substance, while “glycerin” often refers to commercial grades that may contain 95–99.5% glycerol plus water and trace impurities. The density difference between these grades is small (less than 1%) but measurable.

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in t | Temperature | °C | 20 | -50
out density | Density (g/mL) | g/mL | 1.26108 - 0.000615 * t - 0.0000004 * t^2 | 3
out density_kg | Density (kg/m³) | kg/m³ | (1.26108 - 0.000615 * t - 0.0000004 * t^2) * 1000 | 1