Plumbing unit converter
Convert between metric and imperial for the measurements you use on the job — length, pressure, temperature, flow, volume and area. 1 inch = 25.4 mm, 1 bar = 14.5 psi, 1 US gallon = 3.785 litres.
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Millimetres (mm)
2540.000
Length. 1 in = 25.4 mm · tap ⇄ to reverse
Common questions
- How many millimetres are in an inch?
- Exactly 25.4 mm. 1 inch = 25.4 mm, so to convert inches to millimetres multiply by 25.4; to convert mm to inches, divide by 25.4.
- How do you convert bar to psi?
- Multiply bar by 14.5038. 1 bar = 14.5038 psi, so 3 bar ≈ 43.5 psi. Most homes run roughly 2–4 bar (30–60 psi) of water pressure.
- How do you convert litres per minute to GPM?
- Divide litres per minute by 3.78541 to get US gallons per minute, because 1 US GPM = 3.78541 L/min. A 9 L/min shower head is about 2.4 GPM.
- What is 60°C in Fahrenheit?
- 140°F. The formula is °F = °C × 9/5 + 32. A common water-heater setpoint of 60°C equals 140°F.
Reference & education only. Not professional, engineering, or code-compliance advice. Estimates are based on published model codes; local amendments and your Authority Having Jurisdiction (AHJ) govern. Always verify against the current adopted code and a licensed professional before doing work.
Last reviewed 2026-06.