One of the most common specs used to compare projectors is a measure of how bright each model is: lumens. This is because, in theory, a 1,000-lumen projector will be brighter than a 500-lumen projector. With projectors, the brightness not only determines how bright and easy to see the image will be, but also how large the image can be. A brighter projector can create a larger image without being too dim to watch.
Frustratingly, it’s a lot more complex than that. If you’re interested only in the broad strokes of how many lumens you need in a projector, the sections below will cover that. If you’re interested in digging a little deeper, including why the numbers can only ever be used as broad guidelines, further sections will, ahem, illuminate the subject more.