How to Print a Family Tree Poster (Sizes, DPI, and Layout Tips)
Pixels to paper, with the arithmetic shown. Which family tree sizes fit A4, A3, and a 50x70 poster, and when to use a print shop instead of your own printer.
Printing a family tree sounds like the easy part until you collect the order and find that a chart which looked razor-sharp on screen has turned into soft-edged mush on paper. The printer is almost never the culprit. The problem happened earlier, when a file with too few pixels was handed to a shop that was asked to stretch it across half a metre of paper.
The whole subject comes down to one line of arithmetic, so start there.
Pixels divided by DPI equals inches
Print resolution is measured in DPI, dots per inch, and the relationship is a simple division. Take a 3000 by 2000 pixel export and divide each side by 300:
- 3000 ÷ 300 = 10 inches wide
- 2000 ÷ 300 = 6.7 inches tall
So that file prints beautifully at 10 by 6.7 inches, which is a shade smaller than A4 landscape. That is what 300 DPI really buys you, and it surprises people every time, because 3000 pixels feels enormous on a screen.
The same file can go bigger if you accept that posters are not read from reading distance. At 150 DPI, suitable for a poster viewed at arm's length, 3000 pixels gives you 20 inches, roughly 50 cm. At 100 DPI, acceptable for a wall chart people read from across a room, it stretches to 30 inches, or 76 cm. There is no single "correct" DPI; there is only the distance from which the print will be read.
One more number worth knowing: the PNG export from Photo Family Tree is rendered at four times the on-screen layout size, so a chart that measures 1200 by 900 units on screen exports at 4800 by 3600 pixels. That is enough for a large poster, as the sums above show.
Which paper sizes fit which trees
Now work the same math backwards, from paper to pixels, using the common sizes.
A4 is 21 by 29.7 cm, about 8.3 by 11.7 inches. At 300 DPI that needs 2480 by 3508 pixels, which is exactly why a 3000-pixel-wide export falls just short of full-quality A4 landscape. It will still look fine, since charts tolerate 250 DPI without visible loss, but a taller tree on portrait A4 wants more pixels.
A3 is 29.7 by 42 cm, roughly twice the area of A4. Full 300 DPI quality needs 3508 by 4961 pixels. At 150 DPI, which is a fair expectation for a chart that hangs on a wall rather than sitting in a lap, 1754 by 2480 pixels is enough.
A 50 by 70 cm poster is about 19.7 by 27.6 inches. At 300 DPI this would need 5906 by 8268 pixels, a genuinely enormous file that most tools never produce. At 150 DPI it needs 2953 by 4134, which a 4× export clears comfortably. Poster shops routinely print photo posters at 100 to 150 DPI anyway, because nobody reads a poster with their nose against it; check the smallest name on your chart at that size and you will know immediately whether it works.
The practical conclusion: match the chart to the paper before you export. A five-person nuclear tree is an A3 subject. A three-generation chart with a dozen cards belongs on 50 by 70. Trying to print the latter at A4 shrinks every card until the years are illegible. If you have not settled the layout yet, our guide to choosing a photo family tree template sorts designs by family shape rather than by art style.
One exception to the math: vector
Everything above assumes a raster file, pixels arranged in a grid. Photo Family Tree can also export the tree as an SVG, which stores shapes and text as math instead of pixels. A print shop can scale a vector file to any size with no softening at all, which makes it the safest choice for anything wider than about 60 cm. The catch is that plenty of online poster services refuse SVG uploads, so check before you count on it, and fall back to a PNG exported for 150 DPI if they do.
Home printer or print shop
An A4 or A3 print on a decent inkjet is a legitimate option, and for a draft or a child's school project it is the right one. Know what you are getting into first.
Paper weight is the difference between a keepsake and a floppy sheet. Standard office paper is 80 gsm and too thin for a full-coverage photo print; it ripples where the ink goes down heaviest. Use 200 to 250 gsm photo paper for anything you intend to keep. Choose a matte finish for a wall chart. Glossy looks richer in the pack, but under a lamp across from a window it turns into a mirror, and a tree poster gets looked at under lamps.
Ink is the hidden cost. A full-bleed A3 photo print can consume a noticeable fraction of a cartridge set, and repeated drafts eat more than a single print-shop order would have. Most home printers also cannot print borderless reliably, so plan a white margin of at least half an inch and keep card edges inside it.
A print shop is the better call for anything larger than A3. Poster services accept the same PNG you would print at home, typically let you pick matte or glossy, and can mount or frame it. Order matte there too, for the same reason.
The 25 percent test print
Before committing to a big order, print the file at 25 percent scale on a single sheet of A4 and judge that.
The trick works because scale and distance scale together. A 50 by 70 cm poster printed at 25 percent becomes 12.5 by 17.5 cm, which fits on A4 with room to spare. Hold that little proof at 25 cm from your eyes and you are seeing exactly what the full-size poster looks like from one metre away. If the smallest name and the years are comfortable to read on the proof at reading distance, the poster is fine. If you are squinting, the print shop cannot rescue the file; you need a bigger export or a smaller poster.
The same proof exposes the other common failure, which is ink-hungry backgrounds. A dark template that looks handsome on screen can turn a 50 by 70 poster into a smudge magnet and cost a fortune in home ink. Cheaper to discover on a 5-cent proof than on a 30-euro order.
One file, several products
Once the tree exists as a single high-resolution image, everything physical is the same file handed to a different printer: a framed poster for the hallway, a canvas for a grandparent's living room, small 5 by 7 prints as reunion handouts. Build the chart first, in the browser at /, export once, and every keepsake afterwards is a print-shop order away. If you have not settled the photos yet, our guide to a family tree with pictures covers which faces and crops hold up in print.
Do the division before you order, test-print at a quarter size, and ask for matte. That is the entire craft of getting a family tree onto paper without disappointment.