What is 1.5 bar in psi?
1.5 bar is 21.76 psi (1.5 × 14.5038). That is a typical cold fill pressure for a sealed central heating system.
Bar to PSI Calculator
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1 bar = 14.5038 psi = 100 kPa. Most sealed heating systems sit around 1.0–1.5 bar cold; the PRV on a typical boiler lifts at 3 bar (about 43.5 psi).
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This calculator converts pressure between bar and psi, in both directions, and shows the equivalent in kilopascals (kPa) too. Enter a value, pick the direction, and the result appears immediately.
It is built for heating, gas and plumbing work, where boiler gauges are marked in bar but plenty of pumps, gauges and imported specs use psi. A sealed heating system sits around 1.0–1.5 bar cold — about 14.5–21.8 psi — and this is the quickest way to move between the two.
The conversion is fixed and exact: 1 bar equals 14.5038 psi, which is also 100 kPa.
The formula
psi = bar × 14.5038; bar = psi ÷ 14.5038; 1 bar = 100 kPa
To convert bar to psi, multiply by 14.5038. To convert psi to bar, divide by 14.5038. So 1.5 bar is 1.5 × 14.5038 = 21.76 psi, and a 30 psi reading is 30 ÷ 14.5038 = 2.07 bar. One bar is also exactly 100 kPa.
How to use it
- 1
Choose the direction
Select bar → psi or psi → bar depending on which unit you are starting from.
- 2
Enter the value
Type the pressure you want to convert — for example 1.5 with bar → psi selected to convert a cold-fill reading.
- 3
Read the result
The converted value is shown with its unit, along with the equivalent in kPa. 1.5 bar comes out as 21.76 psi (150 kPa).
Guidance & standards
A sealed central heating system should read about 1.0–1.5 bar (14.5–21.8 psi) when cold, rising to roughly 1.5–2.0 bar once hot. The pressure relief valve on most domestic boilers lifts at 3 bar — about 43.5 psi.
kW does not convert to bar: kW is power (a boiler's heat output) while bar is pressure. If you need a boiler output in imperial units, convert kW to BTU/h (1 kW = 3,412 BTU/h) with the unit converter instead.
Results use the exact factor 1 bar = 14.5038 psi. Boiler gauges read gauge pressure (above atmospheric), which is how the figures here are intended to be used. Always sanity-check against the manufacturer's instructions before relying on a figure.
1 bar = 14.5038 psi = 100 kPa. Most sealed heating systems sit around 1.0–1.5 bar cold; the PRV on a typical boiler lifts at 3 bar (about 43.5 psi).
Frequently asked questions
How many psi is 1 bar?
Exactly 14.5038 psi, which is also 100 kPa or 1,000 mbar. To convert any pressure, multiply bar by 14.5038 for psi, or divide psi by 14.5038 for bar.
What should boiler pressure be in psi?
Most sealed systems should sit at 1.0–1.5 bar cold, which is about 14.5–21.8 psi, rising to roughly 22–29 psi (1.5–2.0 bar) once hot. If it climbs toward 3 bar (43.5 psi) the PRV will start to discharge.
Does kW convert to bar?
No — kW measures power and bar measures pressure, so they are not interchangeable. To work with a boiler's heat output in imperial units, convert kW to BTU/h (1 kW = 3,412 BTU/h).
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