topic Problem with some pressure units in Mathcad Prime 11. in Mathcad

Problem with some pressure units in Mathcad Prime 11.

KS_1427135 — Fri, 21 Nov 2025 21:38:21 GMT

Mathcad Prime 11 is ok with the units of atm and psi but has issues when trying to use bar and kpa in all but the SI unit system. Why does these pressure units only are valid in SI unit system? For example, I get the following error messages when in CGS unit system:

"This variable is undefined. Check that the label is set correctly."

When I switch back to the SI unit system it works and removes the error message.

Re: Problem with some pressure units in Mathcad Prime 11.

Werner_E — Sat, 22 Nov 2025 01:56:13 GMT

All seems to work OK in sytems SI and also USCS. The problem only occurs when you switch to CGS. In this system Pa and also MPa is known, but kPa and bar are not. On the other hand SI and USCS don't know unit barye.

I would call it a bug and you may consider reporting it to official PTC support.

As a workaround you could define the necessary units yourself at the top of the sheet, maybe in a collapsed region or at the right not printable area.

For consistency sake you should label the left hand sides as "Unit" so the are also displayed in bold and blue.

Switching the unit system to SI or USCS will give errors, though, because barye is not know in these systems.

So, because all systems are aware of unit Pa it may be better to define

This should work OK in all unit systems.

P.S.: Its really looks like a bug. I just experimented with a user defined units system based on CGS. For pressure I am explicitly offered kPa but when I chose it the default unit still seems to be barye and kPa is unknown.

Re: Problem with some pressure units in Mathcad Prime 11.

KS_1427135 — Sat, 22 Nov 2025 02:07:16 GMT

Thanks for confirming the pressure unit problem and the work around.

Re: Problem with some pressure units in Mathcad Prime 11.

vnamboodheri — Fri, 28 Nov 2025 08:55:05 GMT

Hello @KS_1427135,

It looks like you have a response from a community expert. If it helped you solve your question please mark the reply as the Accepted Solution.
Of course, if you have more to share on your issue, please let the Community know so other community members can continue to help you.

Thanks,
Vivek N.
Community Moderation Team.