Convert Pound per square inch to Inch of water
1 pound per square inch = 27.6799 inch of water (inH₂O). For example, 10 pound per square inch = 276.799 inch of water and 100 pound per square inch = 2,767.99 inch of water. Type any value below to convert pound per square inch to inch of water both ways — it runs entirely in your browser.
Quick answer: Pound per square inch to Inch of water
1 Pound per square inch = 27.6799 Inch of water (psi → inH₂O). To convert pound per square inch to inch of water, multiply by 27.6799. To convert inch of water to pound per square inch, multiply by 0.03612729. 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 pound per square inch-to-inch of water questions.
How to convert Pound per square inch to Inch of water
To convert pound per square inch to inch of water, multiply the number of pound per square inch by the conversion factor 27.6799, because 1 psi = 27.6799 inH₂O. The conversion is linear, so the same factor works for any value — whole numbers, decimals or fractions. For the reverse direction, 1 inH₂O = 0.03612729 psi, so you divide by 27.6799 (or multiply by 0.03612729) to turn inch of water back into pound per square inch.
inH₂O = psi × 27.6799 ·
psi = inH₂O × 0.03612729
- Write down the value you want to convert, in pound per square inch.
- Multiply it by 27.6799.
- The result is the same area/length/quantity expressed in inch of water.
Pound per square inch to Inch of water — worked examples
Each row shows the exact arithmetic so you can follow the conversion step by step. For example, 5 pound per square inch is 138.3995 inch of water because 5 psi × 27.6799 = 138.3995 inH₂O.
| Pound per square inch | Calculation | Inch of water |
|---|---|---|
| 1 psi | 1 psi × 27.6799 = 27.6799 inH₂O | 27.6799 inH₂O |
| 2 psi | 2 psi × 27.6799 = 55.35981 inH₂O | 55.35981 inH₂O |
| 3 psi | 3 psi × 27.6799 = 83.03971 inH₂O | 83.03971 inH₂O |
| 5 psi | 5 psi × 27.6799 = 138.3995 inH₂O | 138.3995 inH₂O |
| 7 psi | 7 psi × 27.6799 = 193.7593 inH₂O | 193.7593 inH₂O |
| 10 psi | 10 psi × 27.6799 = 276.799 inH₂O | 276.799 inH₂O |
| 12 psi | 12 psi × 27.6799 = 332.1589 inH₂O | 332.1589 inH₂O |
| 15 psi | 15 psi × 27.6799 = 415.1986 inH₂O | 415.1986 inH₂O |
| 20 psi | 20 psi × 27.6799 = 553.5981 inH₂O | 553.5981 inH₂O |
| 25 psi | 25 psi × 27.6799 = 691.9976 inH₂O | 691.9976 inH₂O |
| 50 psi | 50 psi × 27.6799 = 1,383.995 inH₂O | 1,383.995 inH₂O |
| 100 psi | 100 psi × 27.6799 = 2,767.99 inH₂O | 2,767.99 inH₂O |
Common Pound per square inch to Inch of water conversions
These are the pound per square inch-to-inch of water values people look up most often. Every figure is computed from the exact factor, so you can rely on them for quick reference:
- 1 pound per square inch = 27.6799 inch of water
- 2 pound per square inch = 55.35981 inch of water
- 2.5 pound per square inch = 69.19976 inch of water
- 3 pound per square inch = 83.03971 inch of water
- 4 pound per square inch = 110.7196 inch of water
- 5 pound per square inch = 138.3995 inch of water
- 6 pound per square inch = 166.0794 inch of water
- 7 pound per square inch = 193.7593 inch of water
- 8 pound per square inch = 221.4392 inch of water
- 9 pound per square inch = 249.1191 inch of water
- 10 pound per square inch = 276.799 inch of water
- 12 pound per square inch = 332.1589 inch of water
- 15 pound per square inch = 415.1986 inch of water
- 20 pound per square inch = 553.5981 inch of water
- 25 pound per square inch = 691.9976 inch of water
- 30 pound per square inch = 830.3971 inch of water
- 50 pound per square inch = 1,383.995 inch of water
- 75 pound per square inch = 2,075.993 inch of water
- 100 pound per square inch = 2,767.99 inch of water
- 200 pound per square inch = 5,535.981 inch of water
- 500 pound per square inch = 13,839.95 inch of water
- 1000 pound per square inch = 27,679.9 inch of water
Pound per square inch to Inch of water conversion chart (both directions)
The chart below converts pound per square inch to inch of water and inch of water to pound per square inch side by side, so it works whichever way you need. 1 pound per square inch = 27.6799 inch of water, and 1 inch of water = 0.03612729 pound per square inch.
| Pound per square inch → Inch of water | Inch of water → Pound per square inch |
|---|---|
| 0.25 psi = 6.919976 inH₂O | 0.25 inH₂O = 0.009031823 psi |
| 0.5 psi = 13.83995 inH₂O | 0.5 inH₂O = 0.01806365 psi |
| 1 psi = 27.6799 inH₂O | 1 inH₂O = 0.03612729 psi |
| 2 psi = 55.35981 inH₂O | 2 inH₂O = 0.07225458 psi |
| 3 psi = 83.03971 inH₂O | 3 inH₂O = 0.1083819 psi |
| 4 psi = 110.7196 inH₂O | 4 inH₂O = 0.1445092 psi |
| 5 psi = 138.3995 inH₂O | 5 inH₂O = 0.1806365 psi |
| 6 psi = 166.0794 inH₂O | 6 inH₂O = 0.2167638 psi |
| 7 psi = 193.7593 inH₂O | 7 inH₂O = 0.252891 psi |
| 8 psi = 221.4392 inH₂O | 8 inH₂O = 0.2890183 psi |
| 9 psi = 249.1191 inH₂O | 9 inH₂O = 0.3251456 psi |
| 10 psi = 276.799 inH₂O | 10 inH₂O = 0.3612729 psi |
| 12 psi = 332.1589 inH₂O | 12 inH₂O = 0.4335275 psi |
| 15 psi = 415.1986 inH₂O | 15 inH₂O = 0.5419094 psi |
| 20 psi = 553.5981 inH₂O | 20 inH₂O = 0.7225458 psi |
| 25 psi = 691.9976 inH₂O | 25 inH₂O = 0.9031823 psi |
| 30 psi = 830.3971 inH₂O | 30 inH₂O = 1.083819 psi |
| 40 psi = 1,107.196 inH₂O | 40 inH₂O = 1.445092 psi |
| 50 psi = 1,383.995 inH₂O | 50 inH₂O = 1.806365 psi |
| 75 psi = 2,075.993 inH₂O | 75 inH₂O = 2.709547 psi |
| 100 psi = 2,767.99 inH₂O | 100 inH₂O = 3.612729 psi |
| 150 psi = 4,151.986 inH₂O | 150 inH₂O = 5.419094 psi |
| 200 psi = 5,535.981 inH₂O | 200 inH₂O = 7.225458 psi |
| 250 psi = 6,919.976 inH₂O | 250 inH₂O = 9.031823 psi |
| 500 psi = 13,839.95 inH₂O | 500 inH₂O = 18.06365 psi |
| 1000 psi = 27,679.9 inH₂O | 1000 inH₂O = 36.12729 psi |
Pound per square inch vs Inch of water: which is bigger?
A pound per square inch is the larger unit: one pound per square inch equals 27.6799 inch of waters. Put another way, you need 27.6799 inch of waters to make a single pound per square inch.
What is a Pound per square inch? History, origin and usage
Pounds per square inch grew directly out of the steam age: boiler safety valves were rated by how many pounds of weight it took to hold them shut over a known area, and the unit survived into every later technology that Britain and the United States industrialised. It never went through a formal international definition of its own — instead it became exact in 1959, when the yard-and-pound agreement fixed the pound and the inch exactly, and again through the fixing of standard gravity, which pins down what a "pound of force" means.
Psi is the standard pressure unit in the United States and remains widely understood in Britain, India and elsewhere: tyre pressures, air compressors, pressure washers, water mains, hydraulic lines and scuba tanks. Car tyres are commonly inflated to around 30 to 35 psi.
Psi is exactly defined but its value in pascals is a decimal that repeats forever, so any written figure is necessarily rounded somewhere. Gauges usually read gauge pressure — the amount above surrounding air — which is why a flat tyre reads zero rather than about 14.7.
What is a Inch of water? History, origin and usage
The inch of water is the imperial counterpart of the millimetre of water, and it became entrenched in North American heating and ventilation practice, where it is usually written "inches WC" for water column. Gas utilities adopted it because household gas supply pressures are small enough that a water manometer reads them comfortably.
Inches of water are used for duct pressure and fan static pressure in heating and air-conditioning, for natural-gas appliance supply pressure, and for cleanroom and filter differential pressures.
Residential natural gas is typically delivered at around 7 inches of water column — a pressure so low that it would barely register on a tyre gauge. An inch of water is exactly 25.4 millimetres of water.
Convert 1 Pound per square inch to other units
It can help to see a pound per square inch next to the other units it is commonly compared with. One pound per square inch (psi) is equal to:
| 1 Pound per square inch equals | Unit |
|---|---|
| 6,894.757 Pa | Pascal |
| 68.94757 hPa | Hectopascal |
| 6.894757 kPa | Kilopascal |
| 0.006894757 MPa | Megapascal |
| 68.94757 mbar | Millibar |
| 0.06894757 bar | Bar |
| 0.06804596 atm | Standard atmosphere |
| 51.71493 Torr | Torr |
| 51.71493 mmHg | Millimetre of mercury |
| 2.036021 inHg | Inch of mercury |
| 703.0696 mmH₂O | Millimetre of water |
| 27.6799 inH₂O | Inch of water |
| 0.07030696 kgf/cm² | Kilogram-force per square centimetre |
Convert 1 Inch of water to other units
One inch of water (inH₂O) is equal to:
| 1 Inch of water equals | Unit |
|---|---|
| 249.0889 Pa | Pascal |
| 2.490889 hPa | Hectopascal |
| 0.2490889 kPa | Kilopascal |
| 0.0002490889 MPa | Megapascal |
| 2.490889 mbar | Millibar |
| 0.002490889 bar | Bar |
| 0.002458316 atm | Standard atmosphere |
| 1.86832 Torr | Torr |
| 1.86832 mmHg | Millimetre of mercury |
| 0.07355591 inHg | Inch of mercury |
| 25.4 mmH₂O | Millimetre of water |
| 0.03612729 psi | Pound per square inch |
| 0.00254 kgf/cm² | Kilogram-force per square centimetre |
Tips for converting Pound per square inch to Inch of water
- To go from pound per square inch to inch of water, multiply by 27.6799; to go back, divide by 27.6799 (or multiply by 0.03612729).
- For a quick mental estimate, remember that 1 pound per square inch ≈ 27.6799 inch of water, so 10 pound per square inch ≈ 276.799 inch of water.
- 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 Pound per square inch to Inch of water converter
Type a number into the Pound per square inch field and the equivalent in Inch of water 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 Inch of water field to convert the other way (inch of water to pound per square inch). 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 psi = 27.6799 inH₂O), 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 pound per square inch-to-inch of water 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 inch of water are in 1 pound per square inch?
- 1 pound per square inch = 27.6799 inch of water (inH₂O). To convert any number of pound per square inch to inch of water, multiply by 27.6799.
- How do I convert pound per square inch to inch of water?
- Multiply the number of pound per square inch by 27.6799. For example, 10 pound per square inch = 10 × 27.6799 = 276.799 inch of water, and 25 pound per square inch = 691.9976 inch of water.
- How many pound per square inch are in 1 inch of water?
- 1 inch of water = 0.03612729 pound per square inch. So to convert inch of water back to pound per square inch, multiply by 0.03612729.
- What is the formula to convert pound per square inch to inch of water?
- inch of water = pound per square inch × 27.6799. The reverse formula is pound per square inch = inch of water × 0.03612729.
- How much is 100 pound per square inch in inch of water?
- 100 pound per square inch = 2,767.99 inch of water. (And 1000 pound per square inch = 27,679.9 inch of water.)
- Which is bigger, a pound per square inch or a inch of water?
- A pound per square inch is larger: 1 pound per square inch = 27.6799 inch of water.
- Is this pound per square inch to inch of water converter accurate?
- Yes — every value is computed from the exact 27.6799 inH₂O per psi factor (not rounded look-up tables), and the factors are re-verified automatically on every update.
- Can I convert inch of water to pound per square inch too?
- Yes. The converter works both ways — enter a value in either field. 1 inch of water = 0.03612729 pound per square inch.