design tool
Poster font size calculator
Text on a poster is readable when its capital letters are at least one two hundredth of the viewing distance tall, so body text read from 1.5 metres needs capitals of 7.5 millimetres, about 31 points. Enter the distance and the poster size to get the minimum for the title, the headings and the body, with a drawing of how they sit on the sheet.
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- Runs on your device, nothing is uploaded
- Free, no sign in
- No watermark, no file limit
How it works
- 1
Pick the poster size
Choose the sheet and whether it hangs portrait or landscape.
- 2
Enter the reading distance
Type how far away people stand to read the body text. At a poster session that is usually 1 to 2 metres.
- 3
Read the three sizes
The table gives the minimum for the title, headings and body, with the capital height and the distance each is read from.
- 4
Check the fit
Read how many characters fit per line, look at the drawing, then press Copy the sizes to paste them into a brief or a style sheet.
The rule behind the numbers
Signage designers size lettering so that a capital letter is about one two hundredth of the distance it is read from: 5 millimetres at a metre, 10 at two metres. A capital is roughly 70% of the font size in most typefaces, and a point is 1/72 of an inch, so 5 millimetre capitals need about 20 point type. The calculator does that arithmetic for each kind of text and rounds up to the next whole point, because the rule is a floor. The A0 poster checker on this site uses the same rule when it measures a finished PDF, so the two agree.
Three distances, not one
A poster is read in stages. People notice the title while walking past, glance at the headings to decide whether to stop, then step in to read the body. So each level is sized for a different distance: the body for the distance you enter, the headings for one and a half times it, and the title for three times it. At 1.5 metres that gives about 31 point body text, 46 point headings and a 92 point title, all well above the 24 point floor poster guides set for body text.
Why the poster size still matters
Readable size depends only on distance, but whether the text fits depends on the sheet. A 92 point title on A0 portrait allows about 43 characters per line once margins are taken off, which is a short title on one line or a long one on two. The same distance on A2 halves that, and the calculator warns when fewer than 12 characters would fit, which means the title needs a bigger sheet, fewer words or a closer audience. The drawing shows the lines at true scale on the sheet, so a cramped layout is visible before a word is written.
How this compares with poster templates
The poster boards in the builder are laid out on a 1656 by 2340 canvas for A0, where each canvas pixel prints at about 1.44 points. Body text is 22 pixels on most section blocks, which is roughly 32 points, and every section heading is 30 pixels, about 43 points. Portrait titles run from 44 to 64 pixels, about 63 to 92 points. Those sit close to what the calculator gives for a reader at 1.5 metres, so a board built from a template is already in range.
Limits worth knowing
The heading and title multipliers are a convention, and a condensed or decorative font may need more than the 70% capital height assumes. Low contrast, dim halls and older readers all argue for going larger than the minimum. Everything is worked out in this tab: nothing is uploaded and nothing is stored, ever.
Limits
- It uses the one two hundredth of distance rule for capital height and assumes capitals are 70% of the font size, which is close for most sans serif faces. The conference's own specification always wins.
- Headings are sized for 1.5 times the reading distance and the title for 3 times. That is a working convention, not a published standard.
- Distances run from 0.3 to 10 metres. Closer is a handout, further is signage, and both get a plain message.
What it does not do
- It does not open or check a poster file; the A0 poster checker measures the text in a PDF.
- It does not choose fonts or line spacing.
- It does not account for poor lighting, low contrast or readers with low vision, which all call for larger text.
Questions people ask
What is the smallest font size for a research poster?
Most poster guides set 24 points as the floor for body text on an A0 or 36 by 48 inch board; the PLOS Computational Biology rules for good posters say never to go below it. The distance rule gives about 20 points at one metre and 31 at one and a half, so 24 is a sensible minimum and 28 to 32 is more comfortable.
How big should a poster title be?
Big enough to read from about three times the body reading distance, because people decide from the corridor whether to stop. For a body read at 1.5 metres that means capitals around 22 millimetres, a 92 point title. Keep it to one or two lines; a title that needs three lines at that size has too many words.
Does the font itself change the size I need?
Yes, slightly. The calculator assumes capitals are 70% of the font size, which suits most sans serif faces such as Arial, Inter or Helvetica. A font with small capitals, a light weight or a condensed width reads smaller at the same point size, so go up a few points. A bold sans serif reads largest for its size from a distance.
What about text on an A3 or A2 poster?
Use the same distance, not a scaled down version of the A0 numbers. A smaller poster is usually read from closer, perhaps 60 centimetres to a metre, which lowers the minimum, but text that would be readable on A0 at the same distance is readable on A3 too. The difference is how much of it fits, which the character counts show.
How many words should a poster have?
Far fewer than most first drafts. At 31 point body text, a third of an A0 sheet holds about 43 characters per line, around seven words, and a reader standing at a poster gives it a minute or two. Write the body, count it with the word counter, then cut methods and background first and keep the finding and the figure.
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Background reading: the question page on this.
Written and checked by the OneCraft team. Last checked .