Ethylene Glycol Freeze Point Chart
Freezing point of ethylene glycol and water, by weight and by volume, in °F or °C.
How to use ↓Wt % and vol % are ethylene glycol in water. Above about 60% the freeze point rises again, so stronger mixes give less protection. Typical values for reference only. Inhibited glycols and brines vary by maker: always use the manufacturer’s data for the fluid you are using.
| Wt % | Vol % pure glycol | Freezes at °F°C |
|---|---|---|
| 0 | 0.0 | 32.00.0 |
| 5 | 4.4 | 29.4−1.4 |
| 10 | 8.9 | 26.2−3.2 |
| 15 | 13.6 | 22.2−5.4 |
| 20 | 18.1 | 17.9−7.8 |
| 21 | 19.2 | 16.8−8.4 |
| 22 | 20.1 | 15.9−8.9 |
| 23 | 21.0 | 14.9−9.5 |
| 24 | 22.0 | 13.7−10.2 |
| 25 | 22.9 | 12.7−10.7 |
| 26 | 23.9 | 11.4−11.4 |
| 27 | 24.8 | 10.4−12.0 |
| 28 | 25.8 | 9.2−12.6 |
| 29 | 26.7 | 8.0−13.3 |
| 30 | 27.7 | 6.7−14.1 |
| 31 | 28.7 | 5.4−14.8 |
| 32 | 29.6 | 4.2−15.4 |
| 33 | 30.6 | 2.9−16.2 |
| 34 | 31.6 | 1.4−17.0 |
| 35 | 32.6 | −0.2−17.9 |
| 36 | 33.5 | −1.5−18.6 |
| 37 | 34.5 | −3.0−19.4 |
| 38 | 35.5 | −4.5−20.3 |
| 39 | 36.5 | −6.4−21.3 |
| 40 | 37.5 | −8.1−22.3 |
| 41 | 38.5 | −9.8−23.2 |
| 42 | 39.5 | −11.7−24.3 |
| 43 | 40.5 | −13.5−25.3 |
| 44 | 41.5 | −15.5−26.4 |
| 45 | 42.5 | −17.5−27.5 |
| 46 | 43.5 | −19.8−28.8 |
| 47 | 44.5 | −21.6−29.8 |
| 48 | 45.5 | −23.9−31.1 |
| 49 | 46.6 | −26.7−32.6 |
| 50 | 47.6 | −28.9−33.8 |
| 51 | 48.6 | −31.2−35.1 |
| 52 | 49.6 | −33.6−36.4 |
| 53 | 50.6 | −36.2−37.9 |
| 54 | 51.6 | −38.8−39.3 |
| 55 | 52.7 | −42.0−41.1 |
| 56 | 53.7 | −44.7−42.6 |
| 57 | 54.7 | −47.5−44.2 |
| 58 | 55.7 | −50.0−45.6 |
| 59 | 56.8 | −52.7−47.1 |
| 60 | 57.8 | −54.9−48.3 |
Vol % is pure glycol by volume. Inhibited concentrates (for example DOWFROST or DOWTHERM SR-1) need slightly more, so use the product’s own chart.
How to use
- Find the freeze point you need in the right-hand column, at least 3 °C (5 °F) below the lowest temperature expected.
- Read across to the concentration: vol % for mixing on site, wt % for a refractometer or lab result.
- Press Print chart for a one-page copy.
About this chart
Ethylene Glycol lowers the freezing point of water: 30% by weight freezes at about 6.7 °F (−14.1 °C) and 50% at about −28.9 °F (−33.8 °C). Ethylene glycol transfers heat better than propylene glycol but is toxic, so it is used in closed industrial and HVAC loops.
Source: Dow DOWTHERM SR-1 and DOWTHERM 4000 Engineering and Operating Guide, Table 3 (typical freezing points of aqueous ethylene glycol), cross-checked against independent freeze-point data. Typical values for reference only. Inhibited glycols and brines vary by maker: always use the manufacturer’s data for the fluid you are using.
FAQ
What is the freezing point of 30% ethylene glycol?
About 6.7 °F (−14.1 °C) at 30% by weight (27.7% by volume).
What is the freezing point of 50% ethylene glycol?
About −28.9 °F (−33.8 °C) at 50% by weight (47.6% by volume).