Address Window Position Checker

Why there are no DIN 5008 presets. DIN 5008 (written business letters, current edition March 2020) defines the address field and its position for the two letter forms A and B, but the standard's text is sold by DIN Media. Public summaries disagree on the exact figures, for example how far from the top edge the address field starts, how wide it is and how far from the left, and the figures differ between editions (the 2011 edition integrated the former DIN 676). A tool that printed one of those sets as "the standard" could mislead you into a wrong letter, so none is built in.

What you enter instead. You type the window area on the sheet: distance from the left edge, distance from the top edge, width and height, in millimetres. Take it from the standard or letter template you have, or measure it: fold a sheet the way it goes into the envelope, mark the window corners through the window, unfold and measure from the top-left corner of the sheet. The tool compares your letter against exactly that rectangle.

What it does not measure. Whether your letter follows DIN 5008 as a whole (margins, fold marks, information block, line spacing, typeface), whether the window area you entered is the correct one, the sender line, or the real envelope. Only the clearance between one address block and one rectangle on page 1 is measured.

What it measures. The address block is found from the text of page 1 (a group of two to nine lines in the top-left area), or typed on a blank sheet with a left and top offset. The result gives the clearance in millimetres on all four sides (negative means it sticks out), tells you which way to move it, and warns when the block is taller or wider than the window. The page is shown with the window outlined, the block marked and a millimetre ruler, and you can print the preview.

Paper. A4 (210 × 297 mm) and US Letter are available; if your first page is another size, the tool measures on that page and says so. Positions depend on the letter, not on the printer; check a printed test page in a real envelope, because printers and folding machines vary by a millimetre or two.

PDF files up to 50 MB (page 1 is checked), or an address typed on a blank A4 or US Letter sheet. Scanned letters with no text layer cannot be analysed: type the block position by hand.

1. Choose the paper and enter the window area (left, top, width, height in mm).
2. Drag in your letter as a PDF, or open No letter yet? and type an address with its left and top offset.
3. Read the clearances and the hint. Adjust the address block numbers if the wrong block was detected.
4. Print the preview or move the address in your template, and test with a real envelope.

• Checking a letter template before you print a few hundred copies
• Finding out how many millimetres to move a mail-merge address block
• Testing whether a five-line address with a sender line still fits the window
• Comparing your letter with the window of a different envelope
• Producing a printed overlay to hold against the light

The result is only as good as the window rectangle you enter. The tool does not know DIN 5008 distances, the fold marks of your template, how your folder positions the sheet in the envelope, or the envelope's own tolerance. It checks one page and one block.

Address-block detection is a heuristic based on lines at the top left of the page; letters with a logo, a sender line and the address close together may need the numbers adjusted by hand.