Convert Inch of mercury to Hectopascal
1 inch of mercury = 33.86389 hectopascal (hPa). For example, 10 inch of mercury = 338.6389 hectopascal and 100 inch of mercury = 3,386.389 hectopascal. Type any value below to convert inch of mercury to hectopascal both ways — it runs entirely in your browser.
Quick answer: Inch of mercury to Hectopascal
1 Inch of mercury = 33.86389 Hectopascal (inHg → hPa). To convert inch of mercury to hectopascal, multiply by 33.86389. To convert hectopascal to inch of mercury, multiply by 0.02952998. The converter at the top does this instantly and both ways; the sections below give the formula, worked examples, a full conversion chart and answers to the most common inch of mercury-to-hectopascal questions.
How to convert Inch of mercury to Hectopascal
To convert inch of mercury to hectopascal, multiply the number of inch of mercury by the conversion factor 33.86389, because 1 inHg = 33.86389 hPa. The conversion is linear, so the same factor works for any value — whole numbers, decimals or fractions. For the reverse direction, 1 hPa = 0.02952998 inHg, so you divide by 33.86389 (or multiply by 0.02952998) to turn hectopascal back into inch of mercury.
hPa = inHg × 33.86389 ·
inHg = hPa × 0.02952998
- Write down the value you want to convert, in inch of mercury.
- Multiply it by 33.86389.
- The result is the same area/length/quantity expressed in hectopascal.
Inch of mercury to Hectopascal — worked examples
Each row shows the exact arithmetic so you can follow the conversion step by step. For example, 5 inch of mercury is 169.3194 hectopascal because 5 inHg × 33.86389 = 169.3194 hPa.
| Inch of mercury | Calculation | Hectopascal |
|---|---|---|
| 1 inHg | 1 inHg × 33.86389 = 33.86389 hPa | 33.86389 hPa |
| 2 inHg | 2 inHg × 33.86389 = 67.72777 hPa | 67.72777 hPa |
| 3 inHg | 3 inHg × 33.86389 = 101.5917 hPa | 101.5917 hPa |
| 5 inHg | 5 inHg × 33.86389 = 169.3194 hPa | 169.3194 hPa |
| 7 inHg | 7 inHg × 33.86389 = 237.0472 hPa | 237.0472 hPa |
| 10 inHg | 10 inHg × 33.86389 = 338.6389 hPa | 338.6389 hPa |
| 12 inHg | 12 inHg × 33.86389 = 406.3666 hPa | 406.3666 hPa |
| 15 inHg | 15 inHg × 33.86389 = 507.9583 hPa | 507.9583 hPa |
| 20 inHg | 20 inHg × 33.86389 = 677.2777 hPa | 677.2777 hPa |
| 25 inHg | 25 inHg × 33.86389 = 846.5972 hPa | 846.5972 hPa |
| 50 inHg | 50 inHg × 33.86389 = 1,693.194 hPa | 1,693.194 hPa |
| 100 inHg | 100 inHg × 33.86389 = 3,386.389 hPa | 3,386.389 hPa |
Common Inch of mercury to Hectopascal conversions
These are the inch of mercury-to-hectopascal values people look up most often. Every figure is computed from the exact factor, so you can rely on them for quick reference:
- 1 inch of mercury = 33.86389 hectopascal
- 2 inch of mercury = 67.72777 hectopascal
- 2.5 inch of mercury = 84.65972 hectopascal
- 3 inch of mercury = 101.5917 hectopascal
- 4 inch of mercury = 135.4555 hectopascal
- 5 inch of mercury = 169.3194 hectopascal
- 6 inch of mercury = 203.1833 hectopascal
- 7 inch of mercury = 237.0472 hectopascal
- 8 inch of mercury = 270.9111 hectopascal
- 9 inch of mercury = 304.775 hectopascal
- 10 inch of mercury = 338.6389 hectopascal
- 12 inch of mercury = 406.3666 hectopascal
- 15 inch of mercury = 507.9583 hectopascal
- 20 inch of mercury = 677.2777 hectopascal
- 25 inch of mercury = 846.5972 hectopascal
- 30 inch of mercury = 1,015.917 hectopascal
- 50 inch of mercury = 1,693.194 hectopascal
- 75 inch of mercury = 2,539.791 hectopascal
- 100 inch of mercury = 3,386.389 hectopascal
- 200 inch of mercury = 6,772.777 hectopascal
- 500 inch of mercury = 16,931.94 hectopascal
- 1000 inch of mercury = 33,863.89 hectopascal
Inch of mercury to Hectopascal conversion chart (both directions)
The chart below converts inch of mercury to hectopascal and hectopascal to inch of mercury side by side, so it works whichever way you need. 1 inch of mercury = 33.86389 hectopascal, and 1 hectopascal = 0.02952998 inch of mercury.
| Inch of mercury → Hectopascal | Hectopascal → Inch of mercury |
|---|---|
| 0.25 inHg = 8.465972 hPa | 0.25 hPa = 0.007382496 inHg |
| 0.5 inHg = 16.93194 hPa | 0.5 hPa = 0.01476499 inHg |
| 1 inHg = 33.86389 hPa | 1 hPa = 0.02952998 inHg |
| 2 inHg = 67.72777 hPa | 2 hPa = 0.05905997 inHg |
| 3 inHg = 101.5917 hPa | 3 hPa = 0.08858995 inHg |
| 4 inHg = 135.4555 hPa | 4 hPa = 0.1181199 inHg |
| 5 inHg = 169.3194 hPa | 5 hPa = 0.1476499 inHg |
| 6 inHg = 203.1833 hPa | 6 hPa = 0.1771799 inHg |
| 7 inHg = 237.0472 hPa | 7 hPa = 0.2067099 inHg |
| 8 inHg = 270.9111 hPa | 8 hPa = 0.2362399 inHg |
| 9 inHg = 304.775 hPa | 9 hPa = 0.2657698 inHg |
| 10 inHg = 338.6389 hPa | 10 hPa = 0.2952998 inHg |
| 12 inHg = 406.3666 hPa | 12 hPa = 0.3543598 inHg |
| 15 inHg = 507.9583 hPa | 15 hPa = 0.4429497 inHg |
| 20 inHg = 677.2777 hPa | 20 hPa = 0.5905997 inHg |
| 25 inHg = 846.5972 hPa | 25 hPa = 0.7382496 inHg |
| 30 inHg = 1,015.917 hPa | 30 hPa = 0.8858995 inHg |
| 40 inHg = 1,354.555 hPa | 40 hPa = 1.181199 inHg |
| 50 inHg = 1,693.194 hPa | 50 hPa = 1.476499 inHg |
| 75 inHg = 2,539.791 hPa | 75 hPa = 2.214749 inHg |
| 100 inHg = 3,386.389 hPa | 100 hPa = 2.952998 inHg |
| 150 inHg = 5,079.583 hPa | 150 hPa = 4.429497 inHg |
| 200 inHg = 6,772.777 hPa | 200 hPa = 5.905997 inHg |
| 250 inHg = 8,465.972 hPa | 250 hPa = 7.382496 inHg |
| 500 inHg = 16,931.94 hPa | 500 hPa = 14.76499 inHg |
| 1000 inHg = 33,863.89 hPa | 1000 hPa = 29.52998 inHg |
Inch of mercury vs Hectopascal: which is bigger?
A inch of mercury is the larger unit: one inch of mercury equals 33.86389 hectopascals. Put another way, you need 33.86389 hectopascals to make a single inch of mercury.
What is a Inch of mercury? History, origin and usage
Inches of mercury come from the same barometers as millimetres of mercury, read off in imperial units. The unit stayed embedded in North American practice long after the metric system spread elsewhere, largely because aviation and broadcast weather standardised on it early and changing would have meant reissuing every altimeter and every chart.
Inches of mercury are used for atmospheric pressure in United States weather reports and, importantly, for altimeter settings in aviation in the US and Canada. They also appear on vacuum gauges for engines and air-conditioning work.
The standard sea-level pressure of 29.92 inHg is one of the most recognisable numbers in aviation — pilots set it as the default altimeter reference. An inch of mercury is exactly 25.4 millimetres of mercury, because the inch itself has been exactly 25.4 mm since 1959.
What is a Hectopascal? History, origin and usage
The hectopascal was adopted by weather services in the 1980s for a very practical reason: it is exactly the same size as the millibar they had been using since the 1900s. Switching to an SI-based name therefore changed nothing on the charts. A forecast that used to read 1013 mb reads 1013 hPa, digit for digit, so decades of records stayed directly comparable.
Hectopascals are the standard unit for atmospheric pressure in weather reports and aviation across most of the world. Sea-level pressure normally sits between about 980 hPa in a deep storm and 1040 hPa in a strong high-pressure system.
"Hecto" means a hundred, so a hectopascal is 100 pascals. It is one of the very few places where the hecto prefix survives in everyday use — almost everywhere else the SI world jumps straight from the base unit to kilo.
Convert 1 Inch of mercury to other units
It can help to see a inch of mercury next to the other units it is commonly compared with. One inch of mercury (inHg) is equal to:
| 1 Inch of mercury equals | Unit |
|---|---|
| 3,386.389 Pa | Pascal |
| 33.86389 hPa | Hectopascal |
| 3.386389 kPa | Kilopascal |
| 0.003386389 MPa | Megapascal |
| 33.86389 mbar | Millibar |
| 0.03386389 bar | Bar |
| 0.03342106 atm | Standard atmosphere |
| 25.4 Torr | Torr |
| 25.4 mmHg | Millimetre of mercury |
| 345.3155 mmH₂O | Millimetre of water |
| 13.5951 inH₂O | Inch of water |
| 0.4911541 psi | Pound per square inch |
| 0.03453155 kgf/cm² | Kilogram-force per square centimetre |
Convert 1 Hectopascal to other units
One hectopascal (hPa) is equal to:
| 1 Hectopascal equals | Unit |
|---|---|
| 100 Pa | Pascal |
| 0.1 kPa | Kilopascal |
| 0.0001 MPa | Megapascal |
| 1 mbar | Millibar |
| 0.001 bar | Bar |
| 0.0009869233 atm | Standard atmosphere |
| 0.7500617 Torr | Torr |
| 0.7500616 mmHg | Millimetre of mercury |
| 0.02952998 inHg | Inch of mercury |
| 10.19716 mmH₂O | Millimetre of water |
| 0.4014631 inH₂O | Inch of water |
| 0.01450377 psi | Pound per square inch |
| 0.001019716 kgf/cm² | Kilogram-force per square centimetre |
Tips for converting Inch of mercury to Hectopascal
- To go from inch of mercury to hectopascal, multiply by 33.86389; to go back, divide by 33.86389 (or multiply by 0.02952998).
- For a quick mental estimate, remember that 1 inch of mercury ≈ 33.86389 hectopascal, so 10 inch of mercury ≈ 338.6389 hectopascal.
- The converter above keeps full precision; the tables round for readability, so use the tool for exact figures.
- Both fields update live as you type — change either side to convert in that direction.
How to use this Inch of mercury to Hectopascal converter
Type a number into the Inch of mercury field and the equivalent in Hectopascal appears instantly — there is no “convert” button to press and nothing is sent to a server, so it works offline once the page has loaded and is safe for any data. You can also type into the Hectopascal field to convert the other way (hectopascal to inch of mercury). Use the swap control to flip the two units, and copy the result with a single click. Because the calculation runs in your browser with full floating-point precision, the converter is more exact than the rounded figures shown in the reference chart above — use the chart for quick look-ups and the tool for precise work.
Accuracy and method
Every figure on this page — the formula, the worked examples, the conversion chart and the “convert to other units” tables — is computed from a single verified conversion factor (1 inHg = 33.86389 hPa), never copied from a hand-typed lookup table that could drift. That factor is derived from each unit’s definition in terms of a common base unit, and an automated check re-verifies all of the site’s factors on every update, so the numbers here stay correct over time. This matters for inch of mercury-to-hectopascal conversions because a small rounding error in a published table compounds quickly at larger quantities; computing from the exact factor avoids that.
Sources
- NIST Special Publication 811 — Guide for the Use of the SI — publishes the exact metric equivalents of the customary pressure units. A psi is one pound of force over one square inch, and the 1959 international yard-and-pound agreement fixes the pound at exactly 0.453 592 37 kilogram and the inch at exactly 0.0254 metre, while standard gravity is fixed at exactly 9.806 65 m/s² — so psi, inches of mercury and inches of water are defined exactly rather than measured.
- BIPM — The International System of Units (SI Brochure) — the defining document for the SI, published by the International Bureau of Weights and Measures. It fixes the base unit that this conversion resolves to, which is why the factor here can be exact rather than approximate.
Pressure factors here come from fixed definitions, anchored to the pascal: a bar is exactly 100,000 Pa, one atmosphere is exactly 101,325 Pa, a torr is exactly a 760th of an atmosphere, and psi is built from the exact pound and the exact inch. Two of them — psi and the torr — work out to decimals that repeat forever, so where a number is shown rounded it is marked, not quietly trimmed.
Frequently asked questions
- How many hectopascal are in 1 inch of mercury?
- 1 inch of mercury = 33.86389 hectopascal (hPa). To convert any number of inch of mercury to hectopascal, multiply by 33.86389.
- How do I convert inch of mercury to hectopascal?
- Multiply the number of inch of mercury by 33.86389. For example, 10 inch of mercury = 10 × 33.86389 = 338.6389 hectopascal, and 25 inch of mercury = 846.5972 hectopascal.
- How many inch of mercury are in 1 hectopascal?
- 1 hectopascal = 0.02952998 inch of mercury. So to convert hectopascal back to inch of mercury, multiply by 0.02952998.
- What is the formula to convert inch of mercury to hectopascal?
- hectopascal = inch of mercury × 33.86389. The reverse formula is inch of mercury = hectopascal × 0.02952998.
- How much is 100 inch of mercury in hectopascal?
- 100 inch of mercury = 3,386.389 hectopascal. (And 1000 inch of mercury = 33,863.89 hectopascal.)
- Which is bigger, a inch of mercury or a hectopascal?
- A inch of mercury is larger: 1 inch of mercury = 33.86389 hectopascal.
- Is this inch of mercury to hectopascal converter accurate?
- Yes — every value is computed from the exact 33.86389 hPa per inHg factor (not rounded look-up tables), and the factors are re-verified automatically on every update.
- Can I convert hectopascal to inch of mercury too?
- Yes. The converter works both ways — enter a value in either field. 1 hectopascal = 0.02952998 inch of mercury.