Pressure Converter
Convert between pascals, kilopascals, bar, millibar, atmospheres, psi, torr, and inHg instantly.
- Free, no account
- No watermark
- No usage limit
About the Pressure Converter
Type a number, tell it the unit you've got, and this pressure converter shows that value in all eight units at once, pascals, kilopascals, bar, millibar, atmospheres, psi, torr, and inches of mercury. No second dropdown, no picking a target. That's the part worth caring about. Most pressure converters make you choose a "from" and a "to", hand back a single number, and if you then need a third unit you run the whole thing again. This one lays every unit out live, so you don't have to know in advance which one you actually want.
That matters more for pressure than for nearly any other measurement, because pressure is the one quantity where every field speaks a different dialect. A weather report is in millibars or hectopascals. A tire shop is in psi or bar. A diver counts atmospheres, a vacuum tech counts down in torr, a pilot sets the altimeter in inches of mercury. Convert one reading and there's a good chance you want to see it in two or three of those, not one. So the tool just gives you all of them.
It runs entirely in your browser. Nothing you type is uploaded, and once the page has loaded it keeps converting with no connection at all.
How to use
- Enter your value in the Value box. Whole number, decimal, or scientific notation like
1.5e5, all fine. - Pick the unit you have in the From dropdown. That's the only choice you make.
- Read the table. It shows your number in all eight units at once and updates the instant you type or change the unit, so there's no convert button to go hunting for.
- Copy any row with the copy link beside it, and the exact figure drops straight into a spec sheet, an email, or a homework answer.
- Copy a shareable link to hand someone the precise conversion. The link carries your value and unit, so whoever opens it lands on the same numbers you're looking at.
One value, every unit at once
Pick a target unit and you've already assumed something, that you know which unit you need. With pressure, half the time you don't, or you need more than one at the same moment. Say you're handed a European hydraulics spec in bar, your shop runs in psi, and the maintenance log wants kPa. One entry, all three sitting there, nothing re-run. That's the whole reason this converter skips the "to" box, it answers the follow-up question before you ask it.
The copy link on each row saves you from re-typing an ugly decimal like 6,894.76 and fat-fingering a digit. And the shareable link is the piece people overlook. It packs your value and unit into the URL, so instead of describing a conversion to a colleague you send them the exact one, and they open it to your numbers rather than a blank tool. For a measurement where the two of you might not even use the same units, that's genuinely handy.
Absolute vs gauge, the reference the number hides
A pressure value tells you the size, but not what it's measured against, and that second half is where people get burned. Absolute pressure is measured from a perfect vacuum, real zero. Gauge pressure is measured from the surrounding air. The gap between the two is one atmosphere, roughly 14.7 psi or 101,325 pascals.
Your tire gauge reads gauge pressure. "32 psi" means 32 above the outside air, which is why a flat tire reads zero even though it's still full of atmosphere. The true absolute pressure in that tire is closer to 47 psi. For a tire that's exactly what you want, you care how much you pumped in, not the grand total.
US specs spell it out with a letter. Psia is absolute, psig is gauge. A compressor rated 100 psig sits at 100 above atmosphere, about 115 psia. Read the wrong one and you're off by a full atmosphere, and that kind of error has burst tanks.
Here's how it ties back to this tool. It does pure unit math. It converts the number you give it and never adds or removes an atmosphere, so a gauge reading stays a gauge reading in the new unit and an absolute reading stays absolute. Convert 32 psig to bar and you get about 2.2 bar, still gauge, not quietly bumped up to absolute. That's the correct behavior, because whether your number is absolute or gauge is a fact about your setup, not something arithmetic can work out for you. Keep track of which one you started with and every conversion here is exact.
Frequently asked questions
How do I convert bar to psi?
Multiply by about 14.5. One bar works out to 14.504 psi, so a car tire at 2.2 bar is around 32 psi and 2.5 bar is about 36. For a quick sanity check in your head, "a bar is roughly 14.5 psi" gets you close enough to catch an obvious mistake. When the number has to be right, type it in and read the psi row exactly, no rounding of your own required.
Is a millibar the same as a hectopascal?
Yes, identical. Both are 100 pascals, two names for one size. Meteorology reported pressure in millibars for decades, then moved to hectopascals to sit inside the SI system, and because the numbers match nothing on the maps had to change. A forecast reading 1013 hPa and an old chart reading 1013 mbar show the same pressure. Standard sea-level pressure is 1013.25 of either, the value your weather app compares against when it flags a system as low.
What is a torr, and why does it equal mmHg?
A torr is 1/760 of a standard atmosphere, about 133.3 pascals, named after Torricelli, who worked out that the atmosphere is what holds a column of mercury up. A column 760 mm tall is exactly what sea-level air supports, so one atmosphere is 760 torr, and one torr equals one millimeter of mercury. That's why a vacuum gauge marked in torr and a blood-pressure cuff marked in mmHg are the same unit doing duty in two different fields.
Why is a standard atmosphere exactly 101,325 pascals?
Because that number was fixed by international agreement as the reference, roughly the average air pressure at sea level, pinned to a constant so the unit has one definite size. Real air pressure at your door drifts up and down with weather and altitude, the defined unit does not. It's also why the cross-conversions come out clean, one atm is exactly 760 torr and exactly 1013.25 hPa, both derived straight from that single definition.
Can it handle negative pressures?
Yes. A negative value is meaningful, it usually means below the reference, a partial vacuum or a gauge reading under the surrounding air. The tool converts it and carries the sign straight through. That said, if you didn't mean to type a minus, a negative result is your cue to look at the input again before you trust it.
Does it work offline?
Once the page has loaded, yes. Every conversion runs on your device with no server in the loop, so it keeps working with no internet, and nothing you enter leaves your machine. It's the same reason the answers appear the moment you type, there's no round trip to wait on.
Which units does it cover?
Pascals, kilopascals, bar, millibar (the same as the hectopascal), atmospheres, psi, torr (the same as mmHg), and inches of mercury. That spans the SI base, the everyday metric units, the European industrial and weather favorites, the sea-level reference, the US mechanical standard, and the two mercury-column units used in vacuum work, medicine, and aviation.