About

Mechanics, fleet managers, and automotive wholesalers often purchase coolants by weight but dispense them by volume. Because the density of glycol-based coolants differs significantly from water, assuming 1 kg equals 1 Liter leads to inventory shortages. A standard 200 kg drum of pure Ethylene Glycol does not contain 200 liters; it contains approximately 180 liters due to high density.

This tool addresses the variable density of automotive coolants. It accounts for the specific chemical composition (Ethylene vs. Propylene) and the concentration state (Concentrate vs. Ready Mix). It also introduces a temperature correction factor, as cold fluid is denser than hot fluid. Correct calculations ensure accurate inventory tracking and precise mixing ratios for engine protection.

Formulas

Volume is derived from mass and density. The density (ρ) depends on the specific glycol type and the temperature (T).

V = mρ(T)

For Ethylene Glycol (Pure), the density decreases as temperature rises. The approximation used for thermal expansion adjustment is:

ρ_final ≈ ρ₂₀ − 0.0008 × (T − 20)

Reference Data

Fluid Type	Density @ 20°C (kg/L)	100 kg in Liters	200 kg (Drum) in Liters
Water (Reference)	0.998	100.2	200.4
Ethylene Glycol (Pure)	1.113	89.8	179.6
Propylene Glycol (Pure)	1.036	96.5	193.1
EG 50/50 Mix	1.070	93.5	186.9
PG 50/50 Mix	1.045	95.7	191.4
EG 30% Mix	1.040	96.1	192.3
EG 60% Mix	1.090	91.7	183.5
OAT Coolant (Premix)	1.065	93.9	187.8

Frequently Asked Questions

Yes. While less volatile than fuel, glycol expands when heated. The difference between cold storage (0°C) and operating temperature (90°C) can alter the volume by several percent, affecting precision filling.

Ethylene Glycol is the standard for most automotive engines due to better heat transfer. Propylene Glycol is less toxic and often used in food-safe environments or specialized machinery. They have different densities, so the conversion factors are not interchangeable.

Check the label or MSDS. "Concentrate" is usually 95%+ glycol. "Ready to Use" or "Premix" is typically 50% water and 50% glycol. Weighing a specific volume (1 Liter) is a quick field test; if it weighs ~1.11kg, it's concentrate. If ~1.07kg, it's 50/50.

No. Washer fluid is methanol or ethanol-based and has a density less than water (~0.95 kg/L), whereas antifreeze is heavier than water.