A 90x50 mm business card is 90 x 50 mm. The sheet is Legal, 216 x 356 mm, a built-in preset in FitPrint. The layout below is what FitPrint produces with its defaults: Fit most packing, Original size scaling, a 5 mm gap between items and a 5 mm side margin. Nothing is scaled: each item is placed at 90 x 50 mm, its true size.

Where each item lands

Positions are millimetres on the Legal sheet as FitPrint wrote them, with y measured from the bottom edge.

x (mm)	y from bottom (mm)	Width (mm)	Height (mm)
12	298	90	50
114	298	90	50
12	240	90	50
114	240	90	50
12	182	90	50
114	182	90	50
12	124	90	50
114	124	90	50
12	66	90	50
114	66	90	50
12	8	90	50
114	8	90	50

What other settings place

Settings	Items per sheet	Placed size
Fit most, 5 mm gap and 5 mm margin (default)	12	90 x 50 mm
Stack, 5 mm gap and 5 mm margin	6	90 x 50 mm
Fit most, no gap or margin	14	90 x 50 mm
Fit most, 10 mm gap and 10 mm margin	10	90 x 50 mm
Stack, no gap or margin	7	90 x 50 mm

Turned portrait, 12 fit: business cards (90x50 mm) (portrait) on Legal (fit most, no gap or margin).

What the status line says

With 12 business cards (90x50 mm) in the list, FitPrint's status line reads exactly "12 items · 1 Legal sheet". Add one more and it reads "13 items · 2 Legal sheets": the extra item starts a new sheet rather than shrinking anything.

How to lay this out in FitPrint

Drag your files in. Open FitPrint and drag your 90x50 mm business card files onto the window. Each file appears in the list with its size in the caption.
Choose the Legal sheet. Click Legal in the sheet preset grid. FitPrint then lays the items out on a 216 x 356 mm sheet.
Keep scaling on Original size. Original size places every item at 100 percent, so a printed item measures exactly what the file says it measures.
Leave packing on Fit most. Fit most packs as many items per sheet as fit. With the default 5 mm gap and 5 mm side margin that is 12 business cards (90x50 mm) per Legal sheet.
Change the gap or side margin only if you need to. The defaults are a 5 mm gap and a 5 mm side margin. The settings table on this page shows what every other recorded setting places on this sheet.
Export and print at actual size. Click Export PDF, then set Scale to 100 percent and Pages per Sheet to 1 in the print dialog so nothing re-scales the exported file.

12 business cards (90x50 mm) fit on one Legal sheet at actual size

Where each item lands

What other settings place

What the status line says

How to lay this out in FitPrint

Related layouts

x (mm)	y from bottom (mm)	Width (mm)	Height (mm)
12	298	90	50
114	298	90	50
12	240	90	50
114	240	90	50
12	182	90	50
114	182	90	50
12	124	90	50
114	124	90	50
12	66	90	50
114	66	90	50
12	8	90	50
114	8	90	50

x (mm)	y from bottom (mm)	Width (mm)	Height (mm)
12	298	90	50
114	298	90	50
12	240	90	50
114	240	90	50
12	182	90	50
114	182	90	50
12	124	90	50
114	124	90	50
12	66	90	50
114	66	90	50
12	8	90	50
114	8	90	50

x (mm)	y from bottom (mm)	Width (mm)	Height (mm)
12	298	90	50
114	298	90	50
12	240	90	50
114	240	90	50
12	182	90	50
114	182	90	50
12	124	90	50
114	124	90	50
12	66	90	50
114	66	90	50
12	8	90	50
114	8	90	50