Is the experimental report paper a3 paper?

Yes, the experimental report paper is usually A3 paper, which means that most of the papers used for experimental reports need a piece of paper as big as A3 to compile experimental reports, and then the experimental report paper is one size of A3 paper, and then its size is twice that of our common A4 paper, which is also commonly known as Octagonal paper, which is a relatively large piece of paper.

Therefore, experimental report paper often uses this kind of paper as the paper for writing reports. Then most of the experimental report papers are made of this kind of paper. Besides this kind of paper, there are other bigger papers. If it is used as A4 paper, it is not suitable for making experimental report paper, because it can't hold so many experimental data and reports.

So the final conclusion is that the experimental report papers are basically written on A3 paper.