Learn/Drafting/Import & Export
Expression Evaluator
At a glance
- Every dimension input accepts math expressions
- Unit suffixes: in, mm, cm, m, ft, yd, deg, rad
- Examples: 10mm, (1/2)in, 5+3, 1.5708rad
- Converts and displays in your current document units automatically
Every numeric input in the Drafting workspace — dimension values, Tab entry in the drawing tools,
offset distances, pattern spacing — runs through the same expression evaluator. Type math instead
of reaching for a calculator: +, -, *, /, and parentheses all work, so (1/2)in, 5+3,
and 3.5 - 1/8 are all valid dimension values.
Units
Attach a unit suffix to any number and it converts on the spot: in, ft, yd, mm, cm, m
(long forms like inches, feet, meters work too), plus the machinist shorthands " for
inches and ' for feet. Units mix freely within one expression — 1in + 3mm is fine. A bare
number takes your Settings → Preferred Units, so 10 means 10 mm in metric mode and 10 inches
in inch mode, and the result always displays in your preferred units regardless of what you typed.
Angle inputs use the same machinery with deg and rad suffixes; a bare number is degrees, so
1.5708rad and 90 are the same angle.
Where it matters
Working in inches on a print dimensioned in millimeters (or vice versa), you never convert by
hand — type the value as printed, with its unit, and JetCad3 does the arithmetic exactly. The one
deliberate exception: the Scale tool's factor is unitless, so 2 always means 2×, not 2 mm.