Envelope and insert fit checker
Compare measured envelope and card dimensions, test a 90 degree rotation and check clearance at each edge. Download a free fit plan.
Measure the usable interior with a physical sample, excluding seams and obstructions. Enter the finished, folded size of the insert. All measurements are in millimeters (1 inch = 25.4 mm).
The starting values are an invented measurement example, not a standard envelope size. The 2 mm clearance is an adjustable planning assumption.
It fits as entered, with 2.50 mm spare at each side and 2.50 mm at top and bottom. That meets your 2 mm clearance.
As entered
Meets your entered clearance
Centered gap at each side: 2.50 mm.
Centered gap at top and bottom: 2.50 mm.
Rotated 90°
Insert exceeds the usable interior
Centered gap at each side: -22.50 mm.
Centered gap at top and bottom: 27.50 mm.
Green: usable envelope interior. Dashed outline: insert. Negative gaps mean the insert extends past an edge. The preview is proportional, not actual size. Only 0° and 90° orientations are compared.
Order the pair that fits.
Once the measurements work, choose the envelope and the card together.
See colored envelopesWhat the example means
A 115 × 165 mm insert in a measured 120 × 170 mm interior leaves 5 mm total spare width and height, or 2.5 mm at each centered edge. That meets the entered 2 mm requirement. It does not prove that a thick stack will slide through the opening or that the flap will close.
Test the complete mailing assembly
Fold the insert first, then include every card, liner and other item in the real stack. Check the opening, seams and flap closure. This tool does not model thickness, bending, diagonal insertion, address windows, machine insertion or postal rules. An exact outline fit with zero clearance leaves no handling room.
Envelope makers quote nominal sizes, and the usable space inside is smaller. Use a sample to measure it. No standard size presets are assumed here.
How this tool works
Centered horizontal gap per edge = (usable envelope width − insert width) ÷ 2. Vertical gap uses heights. A candidate meets the entered clearance only when both gaps are at least that clearance. Rotated comparison swaps insert width and height.
Use the actual specification from your selected printer. Defaults are examples, not universal production requirements. These tools do not inspect a PDF, certify a print file, provide a price quote or predict sales.