Frequently Asked Questions

Q: What is French gauge and how does it convert to millimetres?

French gauge (Fr), also called the Charrière scale, is used to size catheters and tubing. One French equals exactly one third of a millimetre (1 Fr = 0.333 mm), so the outer diameter in millimetres equals the French size divided by three.

Q: How do I convert psi to bar?

One bar equals 14.5038 psi. To convert psi to bar, divide by 14.5038; to convert bar to psi, multiply by 14.5038.

Q: How do I convert Celsius to Fahrenheit?

Multiply the Celsius value by 9/5 and add 32. For example, 100 degrees Celsius equals 212 degrees Fahrenheit.

Common conversions and how GAUGE works.

Using GAUGE

How does Smart Convert work?

Type a conversion in plain English, such as "3 bar in psi" or "100 c to f". GAUGE interprets the request to identify the value and the two units, then computes the result with its built-in, verified engine. The wording is interpreted by a language layer; the math is not — it is always calculated, so the answer is exact.

Is this more reliable than asking a chatbot to convert units?

Yes, by design. General-purpose AI assistants generate their answers token by token and can occasionally produce arithmetic errors or misremember a conversion factor. GAUGE only uses language understanding to figure out what you want converted; the actual number comes from a fixed calculation engine built on published SI factors, so it does not "hallucinate" results.

Where do the conversion factors come from?

Factors are based on internationally recognized SI definitions and standards. All conversions route through one engine and are round-trip tested so that converting a value and converting it back returns the original.

Common conversions

What is French gauge, and how does it convert to millimetres?

French gauge (Fr), also called the Charrière scale, sizes catheters and tubing by outer diameter. One French equals exactly one third of a millimetre, so 1 Fr = 0.333 mm and the diameter in millimetres is simply the French size divided by three. A 12 Fr catheter is therefore 4 mm in outer diameter.

How do I convert psi to bar?

One bar equals 14.5038 psi. Divide psi by 14.5038 to get bar, or multiply bar by 14.5038 to get psi. So 30 psi is about 2.07 bar.

How do I convert Celsius to Fahrenheit?

Multiply by 9/5 and add 32. For instance, 100 °C = 212 °F. Going the other way, subtract 32 then multiply by 5/9.

What is the difference between US and UK (imperial) gallons?

They are not the same. A US gallon is about 3.785 litres, while a UK/imperial gallon is about 4.546 litres — roughly 20% larger. GAUGE lists both so you can pick the correct one.

Why do some results show in scientific notation?

Very large or very small results (for example, radiation activity in becquerels, or magnetic flux in maxwells) are shown in scientific notation so they stay readable and precise rather than running to many digits.

Have a unit you'd like added, or spotted something that looks off? Let us know on the contact page.