"Format" is doing a lot of work in the phrase letterhead format in Word. Some of it is the file format — .docx versus .dotx. Most of it is the page itself: margins, header height, type sizes, the spacing of an address line. Those are the rules that decide whether a letter looks composed or looks improvised. None of them are arbitrary, and none of them are matters of taste. This post lays them out with real numbers and the reasoning behind each. It is a spoke off the broader guide to building a letterhead in Word — read that for the full picture, read this for the measurements.
Page setup: US Letter or A4
The first decision is paper size, and it is not a preference — it has to match the paper your correspondence is actually printed and read on.
- US Letter (8.5 × 11 in) — the correct size for North America. Every domestic letter, every printer in a US office, defaults to it.
- A4 (210 × 297 mm) — the standard for the UK, Europe, Australia, and most of the rest of the world.
A4 is 18mm taller and 6mm narrower than Letter. That difference is enough to shift every margin if you set up the page for one size and print on the other. If your correspondence crosses borders, you do not pick one — you set up both, with the artwork positioned for each. A letterhead built on Letter dimensions and printed on A4 will sit too high on the page with a too-wide right margin. The fix is not nudging; it is a second page setup.
In Word: Layout → Size, then Letter or A4. Do this before anything else, because margins and header height are measured against the page you have chosen.
Margins: where the body text lives
Margins on a letterhead are not the usual 1-inch-all-round default. The top margin has to clear the header artwork; the bottom has to clear the footer. As a starting point:
- Top: 1.75" — leaves room for a typical header band.
- Bottom: 1" — clears a modest footer rule and one or two lines of fine print.
- Sides: 0.75" — slightly tighter than default, which gives the body a measured, formal column width.
Set these under Layout → Margins → Custom Margins. They are a starting point, not a law. The top margin in particular depends entirely on how tall your header artwork is — a deep crest-and-address block needs more than 1.75"; a single line of type needs less. The principle is fixed even when the number is not: the first line of body text must clear the artwork with a clean band of white space between them, never crowding it and never floating an inch too low.
Header height: how much of the page the artwork takes
A letterhead header is a proportion problem. Too tall and the page reads as a brochure; too short and it reads as an afterthought. The workable range is roughly 12% to 20% of the page height for the header artwork.
On US Letter — an 11-inch page — that is about 1.3" to 2.2" of header. The 1.75" top margin sits inside that range deliberately: it assumes a header occupying the top sixth or so of the page. A header that runs past 20% starts eating the space a one-page letter needs to breathe; below 12%, the identity stops carrying any weight.
The footer should be smaller than the header — typically half its height or less. A footer that competes with the header for visual weight makes the page feel boxed-in. The header announces; the footer notes. Their sizes should say so.
Type: serif or sans, and the size pattern
Two type decisions matter, and both are conventional rather than creative.
Serif or sans. A serif face — Garamond, Caslon, a good Times — reads as traditional and is the default for law firms, family offices, and formal correspondence. A sans-serif reads as modern and suits studios, agencies, and technology businesses. Pick the one that matches how the organisation actually presents itself; do not mix two serifs or two sans faces in one letterhead.
The size pattern. This is the part people get wrong most often. A letterhead header has two pieces of type and they are not the same size:
- Business or firm name: 18–22pt. Large enough to be the clear first thing the eye lands on. This is the only element that should be loud.
- Address line: 9–10pt. Deliberately small and usually a muted gray. It is reference information, not a headline.
The gap between those two sizes is the point. A name set at 14pt and an address at 12pt produces a header with no hierarchy — everything shouts at the same volume, so nothing leads. The 2× difference between roughly 20pt and roughly 10pt is what makes a header read as name, then details instead of a block of undifferentiated text.
The address line: tracking and the en-dot separator
The address line is one continuous line of small type, and small type set with default spacing looks cramped. Two conventions fix it.
Tracking. Add a little letter-spacing — tracking — to the address line. In Word: select the line, Font dialog → Advanced → Spacing → Expanded, by about 0.3 to 0.5pt. At 9–10pt this opens the line just enough to read as composed rather than dense. Do not over-track; past about 1pt the line starts to look spaced-out and gappy.
The separator. Address elements are joined with a centred dot, not commas or slashes:
123 Main St · City, State 00000 · (555) 123-4567 · you@yourdomain.com
That dot is the en-dot — typographically a middle dot (·), inserted in Word with Insert → Symbol or as a · character. Put a space on each side. It separates the parts of the address without the visual clutter of punctuation and without the line-break risk of a slash. Commas inside an element (City, State) still use commas; the dot only separates the major blocks.
The footer: rule line, URL, registration number
A footer is optional, and a lot of letterheads are stronger without one. When there is a footer, it usually holds some combination of three things, and each belongs only in certain situations.
- A rule line — a thin horizontal rule across the top of the footer band. It belongs when the footer carries enough content to need visual separation from the body. A footer with a single line of type does not need a rule above it.
- A website URL — belongs when the footer is the natural home for contact details that did not fit the header address line. If the URL is already in the header, repeating it in the footer is noise.
- A registration number — a company registration number, bar number, or charity number. This belongs when the entity is legally required to display it, which is common for UK limited companies and regulated firms. It is fine print: set it at 8–9pt, muted, and do not let it become a design element.
The footer should never try to balance the header. Its job is to hold the legal and reference details the header had no room for — quietly.
File format: .docx or .dotx
The other meaning of "format" is the file itself. A .docx is an ordinary document — opening it edits that file. A .dotx is a template — double-clicking it opens a fresh, untitled copy, so the master is never overwritten.
For a letterhead one person drafts from, a .docx is fine. For one a team shares, a .dotx removes the risk of someone saving their letter over the master. The full reasoning is in .dotx vs .docx for letterhead. The format choice does not change any of the page rules above — it only changes what happens when the file is opened.
Continuation pages and first-page-different
A formal letter that runs past one page has a format rule of its own: the first page carries the full letterhead, and the following pages carry a smaller continuation header — often just the firm name and a page number — so the full artwork does not repeat at full size on every sheet.
Word supports this directly through the "Different First Page" header setting, but configuring it by hand against converted artwork is fiddly. A multi-page letterhead conversion builds the first-page-different structure in for you, so page one shows the full letterhead and continuation pages show the reduced header automatically.
When the format rules don't matter
Every rule above applies to building a letterhead in Word from nothing — choosing the type, setting the tracking, deciding the header proportion. If you are starting from a blank document, the letterhead format setup tool walks the page setup, and the letterhead-to-Word template tool gives you a structured starting point.
But there is a situation where none of it matters: you already have a designed PDF letterhead. A designer or a stationer already made the type decisions, set the tracking, and chose the header proportion. Recreating those choices in Word by hand will reproduce them worse — Word cannot kern or set tracking the way a typesetting program can, and it will not match foil or engraving at all.
In that case the right move is not to format anything. It is to lift the existing design straight into Word — artwork locked into the header and footer, body left clean to type in. The PDF-to-Word letterhead converter does exactly that, and it runs entirely in your browser, so the PDF — which for a law firm or a design agency may carry a confidential client name — never leaves your device. A Single conversion is $19 per page; the Multi-page bundle is $49 flat for up to 10 pages and returns .docx, .dotx, A4, and US Letter together. The format rules in this post are how you would rebuild a letterhead. When you already own one, the faster and more faithful answer is not to rebuild it at all.