The layout of the magazine is arranged according to the opposite page. That is to say, when the left and right pages add up, experienced designers and typesetters will leave 1~2cm bleeding in the middle seam (middle seam bleeding is the gap left by preventing words from being nailed inside when binding), but the amount of bleeding left by different binding methods is different, so you can typeset the whole page according to your own ideas in general typesetting, so don't worry about many estimates. You may be a novice and need a lot of attention. Accumulate experience slowly, don't worry, ask for advice modestly, and communicate with the printing factory in time if you enter the printing market. At present, the printing factory has artists and color proofreaders, and they have computers that will add bleeding size to your source files according to the binding method you need. It is recommended that you use professional typesetting software when designing, and most of the data needed for typesetting are for reference. For example, there is a software called AI, which is relatively easy to use. I would like to add that the typesetting suggestions of China Pictorial, magazines and picture books all follow the big characters. There are also some unwritten rules, such as, don't appear full-page text, don't appear full-page scattered pictures. Graphics can be cut and overlapped, but try to avoid arrangement. Then the biggest habit is that a pair of pages are basically big pictures and small pictures with a paragraph of text inserted, or the typesetting of a scattered word-P must have big pictures and small pictures. A magazine should try not to be full of words and small pictures, or the whole text. If you still don't understand, please ask. I hope it will help you and I hope it will be adopted.