Notes written beside the board
A few questions come up so often, and take so long to answer properly, that answering them next to the export button would be in the way: how many pictures will genuinely fit, what the file needs before a printer makes a good job of it, which sizes a phone app wants, and why the board suggests the layouts it does.
Each was written against the same tool you are using, with the same numbers the panels show. Where a piece says a setting exists, it exists.
A hundred photographs on one board
Where the number of pictures and the size of the paper argue with each other, and who should win.
Counts from fifty upward, cell sizes worked out against real paper sizes, what a gutter costs you at each step, and the width in millimetres below which a face on a wall stops being a particular person. Read it before you decide how big to print, not after.
Answers: How small is too small?
Getting a board printed
The arithmetic between a pixel count and a sheet of paper, and the file a print shop actually wants.
Dots per inch as a relationship rather than a property, the standard sizes written out as pixels, bleed and margins on a board that draws neither, and the honest comparison between sending a very large PNG and a high-quality JPEG. Read it before you export, because two of its decisions are board settings.
Answers: What do I send them?
How much of each photo a layout keeps
The one number every suggestion here is ranked by, worked out from two shapes.
Why a landscape in a square cell keeps two thirds of itself, why orientation beats everything else, worked figures for posts, stories and wallpapers, and the small penalties for empty cells and cut faces that decide between two close layouts.
Answers: Why did it suggest that layout?
Instagram collage sizes
Post, story, grid and cover sizes, and which numbers come from the platform itself.
1080 pixels wide and why making it bigger only adds bytes, the 4:5 portrait, the story bands, the posting order of a profile grid, and the slice of a Facebook cover a phone actually shows.
Answers: What size should I make it?
Print sizes and DPI for India
A4, A3, A5, 4 × 6 in, 5 × 7 in and chart paper written out as pixels.
What a cyber café or photo lab needs from the file, why the DPI is written inside it, actual size against fit to page, and the printer-margin setting for home inkjets.
Answers: Will it print the right size?
Not written yet
A note on scanning a shoebox of prints well enough to put on a board, and one on colour, which the pieces above step around. Both are real subjects and neither is written yet.
Back to the board
Reading any of these is optional. An empty board at twelve by eighteen inches opens in a second and will tell you more in five minutes than a page of prose will, and the grid generator will show you what a hundred cells look like faster than the arithmetic will.