A poster is read from across a room, a hallway or a street, so it needs a few very large words. That is why game day posters say "GO TIGERS" and campaign posters say a name and a slogan, and why most of the design work is deciding what to leave out.
Type a top line, a headline of one to three short lines, a line under it and a bottom line. The headline grows to fill the space. Choose big text on color, a full photo with the text at the bottom, or a photo on top with the text below, then pick a print size. The poster is made in your browser and nothing is uploaded.
Poster ideas that work
For a football or school sports poster, use the team name or a chant as the headline, the opponent under it and the date and field on the bottom line. School colors as the background make it recognisable from far away.
For a campaign poster, the name is the headline and the office or slogan goes under it. For an event, the headline is the event itself. In each case one idea in large letters beats three ideas in small ones.
Sizes and printing
The downloads are 100 pixels per inch at full size: 1800 x 2400 for 18 x 24 inches and 1600 x 2400 for the 2:3 shape that 24 x 36 inch posters use, printed larger. That is enough for a poster seen from a few steps away. For text you read up close, print at 11 x 17 inches.
Print shops accept PNG files. For a handout use the flyer maker, and for wall art from a photo see the wall art mockup generator.