Unit systems
Each sheet carries one unit system. It governs one thing only: how answers are shown. The numbers and units you typed are never rewritten. Switching to USCS does not convert your inputs, invalidate your sheet, or lose precision. It changes the units printed in the answer chips.
Change the system
On the Home tab, the System group has a control labelled Units with three choices.
| Choice | What answers display in |
|---|---|
| SI (m, kg, s) | Metric, and the default for a new sheet. |
| USCS (ft, lb) | Foot–pound display: ft, lb, psi, and their relatives. |
| CGS (cm, g) | Centimetre–gram–second display. |
The status bar on the right repeats SI, USCS, or CGS so you can see at a glance which convention a sheet follows. That label is a readout rather than a control. Change the system from the Home dropdown. The Document tab does not carry this setting either.
What actually changes
Choosing a system saves it on the worksheet and runs Evaluate All. A length
entered as 4 m is still four metres afterwards. On a USCS sheet
the chip may report the equivalent in feet. Forces, pressures, and energies
behave the same way. Within SI, answers settle into coherent unprefixed
units, so 20 kN displays as 20000 N, while lengths below a metre
show in mm and pressures show in Pa until they reach about 1 MPa.
Two things outrank the system for a single region:
to() in the expression,
and a pinned unit on the
answer chip. Neither is affected by later switching between SI, USCS, and
CGS. Use them when one line must stay in a particular unit no matter who
opens the sheet. Everything else follows the
units you typed.
Next, conversion with to() when one line has to come out in a particular unit and stay there.