Propylene Glycol Freeze Point Chart
Freezing point of propylene glycol and water, by weight and by volume, in °F or °C.
How to use ↓Wt % and vol % are propylene glycol in water. 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 | 4.8 | 29.1−1.6 |
| 10 | 9.6 | 26.1−3.3 |
| 15 | 14.5 | 22.9−5.1 |
| 20 | 19.4 | 19.2−7.1 |
| 21 | 20.4 | 18.3−7.6 |
| 22 | 21.4 | 17.6−8.0 |
| 23 | 22.4 | 16.6−8.6 |
| 24 | 23.4 | 15.6−9.1 |
| 25 | 24.4 | 14.7−9.6 |
| 26 | 25.3 | 13.7−10.2 |
| 27 | 26.4 | 12.6−10.8 |
| 28 | 27.4 | 11.5−11.4 |
| 29 | 28.4 | 10.4−12.0 |
| 30 | 29.4 | 9.2−12.7 |
| 31 | 30.4 | 7.9−13.4 |
| 32 | 31.4 | 6.6−14.1 |
| 33 | 32.4 | 5.3−14.8 |
| 34 | 33.5 | 3.9−15.6 |
| 35 | 34.4 | 2.4−16.4 |
| 36 | 35.5 | 0.8−17.3 |
| 37 | 36.5 | −0.8−18.2 |
| 38 | 37.5 | −2.4−19.1 |
| 39 | 38.5 | −4.2−20.1 |
| 40 | 39.6 | −6.0−21.1 |
| 41 | 40.6 | −7.8−22.1 |
| 42 | 41.6 | −9.8−23.2 |
| 43 | 42.6 | −11.8−24.3 |
| 44 | 43.7 | −13.9−25.5 |
| 45 | 44.7 | −16.1−26.7 |
| 46 | 45.7 | −18.3−27.9 |
| 47 | 46.8 | −18.7−28.1† |
| 48 | 47.8 | −21.0−29.4† |
| 49 | 48.9 | −23.4−30.7† |
| 50 | 49.9 | −25.9−32.1† |
| 51 | 50.9 | −28.5−33.6† |
| 52 | 51.9 | −31.3−35.1† |
| 53 | 53.0 | −34.1−36.7† |
| 54 | 54.0 | −37.1−38.4† |
| 55 | 55.0 | −40.2−40.1† |
| 56 | 56.0 | −43.5−41.9† |
| 57 | 57.0 | −46.9−43.8† |
| 58 | 58.0 | −50.4−45.8† |
| 59 | 59.0 | −54.1−47.8† |
| 60 | 60.0 | −58.0−50.0† |
† 47–60 wt %: the two sources differ by up to 1.4 K, so the warmer is shown: the IIR secondary-fluid data (Melinder). The Dow DOWFROST table (Table 3) lists these rows colder.
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
Propylene Glycol lowers the freezing point of water: 30% by weight freezes at about 9.2 °F (−12.7 °C) and 50% at about −25.9 °F (−32.1 °C). Propylene glycol is the low-toxicity choice for food plants, potable-water heat exchangers and anywhere a leak could reach people or drains.
Source: Dow DOWFROST Engineering and Operating Guide, Table 3 (typical freezing points of aqueous propylene 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% propylene glycol?
About 9.2 °F (−12.7 °C) at 30% by weight (29.4% by volume).
What is the freezing point of 50% propylene glycol?
About −25.9 °F (−32.1 °C) at 50% by weight (49.9% by volume).