Convert Inches of Mercury to Kilopascals (inHg to kPa)
1 inch of mercury (inHg) equals 3.38638864 kilopascals (kPa).
1 inHg = 3.38638864 kPa
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk inch of mercury to kilopascal converter to paste a column from Excel.
How to Convert Inch of Mercury to Kilopascal
- 1 inHg = 3.38638864 kPa
- 1 kPa = 0.295299833 inHg
- Example: convert 15 inHg to kPa: 15 inHg = 15 × 3.38638864 kPa = 50.79582961 kPa
Reference conditions. inHg: Conventional mercury column: ρ = 13 595.1 kg/m³ and gₙ = 9.80665 m/s² (≈ mercury at 0 °C / 32 °F).
Formula
kPa = inHg × 3.386388640341
Derivation from SI units:
- 1 inHg = 13 595.1 kg/m³ × 9.80665 m/s² × 0.0254 m = 3386.388640341 Pa
- 1 kPa = 10³ Pa
- 1 inHg = 3386.388640341 Pa ÷ 1000 Pa per kPa = 3.386388640341 kPa
Both units are defined exactly, so the factor is exact. Inch of Mercury definition: inch of mercury; Kilopascal definition: kilopascal.
Worked examples
- The standard altimeter setting, 29.92 inHg, is 101.3207481 kPa.
29.92 inHg × 3.38638864 = 101.3207481 kPa - An engine vacuum of 20 inHg is 67.72777281 kPa.
20 inHg × 3.38638864 = 67.72777281 kPa
Inch of Mercury to Kilopascal conversion table
| Inches of Mercury (inHg) | Kilopascals (kPa) |
|---|---|
| 0.5 inHg | 1.69319432 kPa |
| 1 inHg | 3.38638864 kPa |
| 2 inHg | 6.772777281 kPa |
| 5 inHg | 16.9319432 kPa |
| 10 inHg | 33.8638864 kPa |
| 15 inHg | 50.79582961 kPa |
| 20 inHg | 67.72777281 kPa |
| 25 inHg | 84.65971601 kPa |
| 28 inHg | 94.81888193 kPa |
| 28.5 inHg | 96.51207625 kPa |
| 29 inHg | 98.20527057 kPa |
| 29.5 inHg | 99.89846489 kPa |
| 29.92 inHg | 101.3207481 kPa |
| 30 inHg | 101.5916592 kPa |
| 30.5 inHg | 103.2848535 kPa |
| 31 inHg | 104.9780479 kPa |
Where it's used
US barometric and vacuum readings in inHg are converted to kPa for SI calculations and international reports.
Inch of Mercury to other pressure units
| Conversion | 1 inHg equals |
|---|---|
| inch of mercury to pascal | 3386.38864 Pa |
| inch of mercury to kilopascal | 3.38638864 kPa |
| inch of mercury to megapascal | 0.00338638864 MPa |
| inch of mercury to psi | 0.4911541475 psi |
| inch of mercury to bar | 0.0338638864 bar |
| inch of mercury to millibar | 33.8638864 mbar |
| inch of mercury to decibar | 0.338638864 dbar |
| inch of mercury to torr | 25.40000362 Torr |
| inch of mercury to millimeter of mercury | 25.4 mmHg |
| inch of mercury to millimeter of water | 345.31554 mmH₂O |
| inch of mercury to centimeter of water | 34.531554 cmH₂O |
| inch of mercury to inch of water | 13.5951 inH₂O |
| inch of mercury to inch of water (60 °F) | 13.60869892 inH₂O (60 °F) |
| inch of mercury to atmosphere | 0.03342105739 atm |
| inch of mercury to barye | 33863.8864 Ba |
Frequently asked questions
How many kPa is 1 inHg?
1 inHg = 3.38638864 kPa.
How many kilopascals are in 1 inch of mercury?
1 inHg = 3.38638864 kPa.
How do I convert inches of mercury to kilopascals?
Multiply the value in inHg by 3.38638864. For example, 15 inHg × 3.38638864 = 50.79582961 kPa.
Is the inHg to kPa conversion exact?
Yes. Both units are defined exactly, so the ratio is exact; its decimal form does not terminate and is shown here to 10 significant figures (more with the precision selector).
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "inch of mercury, conventional (inHg)".
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 7, SI prefixes.
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert Inches of Mercury to Kilopascals (inHg to kPa). Retrieved October 18, 2026, from https://scientificconverters.com/pressure/inch-of-mercury-to-kilopascal/
IEEE
Scientific Converters, "Convert Inches of Mercury to Kilopascals (inHg to kPa)," scientificconverters.com. Accessed: Oct. 18, 2026. [Online]. Available: https://scientificconverters.com/pressure/inch-of-mercury-to-kilopascal/