Sketchpads are personal things so it is important that you choose one that is right for you. For beginners I recommend a good general purpose sketchpad in A4. A4 is big enough to create sketches and studies but it is also compact enough to fit into a bag and carry around with ease.
The general trend that I observe is that most beginners like to start with A4 and as they become more comfortable they often upsize and move to A3. Think about the way you draw, if you are someone who likes small details then A4 is fine, it may even seem too big at first. It is always best to give yourself room to draw.
If you like drawing with bold lines and your work is larger you might consider an A3 sketchpad. A3 can feel a bit bulky to carry around as it won’t fit into a bag. It is still worth getting the size that is right for your style of drawing because feeling constricted will not lead to expressive drawing and will change the way you draw naturally.
What about A5 or smaller? I think there is a place for these smaller sketchpads, they are great for drawing out of doors or jotting down ideas, making observation sketches when you are out and about. They are extremely portable, light and easy to store in a pocket or bag.
Ideally you will have an A4 or A3 and a A5 or pocket sketchpad for all occasions. If you don’t want to spend so much then I would just stick to one A4 good quality sketchpad.
Once you have decided on the size, there are more decisions:
Spiral-bound or glue-bound?
Hardback or paperback?
Thick or thin paper?
I shall be writing another post about paper types but I would recommend all beginners purchase a sketchpad with good quality cartridge paper for drawing of at least 150 gsm. A good quality sketchpad usually has paper of about 300 gsm. gsm refers to the paper weight which tells us how thick the paper is. Bear in mind that if you want to paint in your sketchpad you will need at least 300 gsm for the paper not to buckle and if you are using watercolour this is still likely to happen. A sketchpad is generally used for dry media or very small painting studies.
I would spend a bit more and get good quality thick paper of around 300 gsm, as a sketchpad is an important material, one of the most important things you will buy. I also like hard-backed sketchpads they give you support when you are drawing so you can lean on them and hold your sketchpad at angles.
You tend to get what you pay for with sketchpads and there is nothing worse than thin paper that falls out because it badly bound. The spiral bound sketchpads are better for tearing out pages, which beginners often do! However one learner had nothing left in her sketchpad because she kept tearing pages out. In this case maybe a good glue-bound sketchpad could stop this temptation!
The most important thing is to find the sketchpad that suits you best. Have a good look at all the options and feel the quality of the paper before you buy! I never buy sketchpads that are sealed because I think it is a must that I feel the paper quality. I had a friend who never liked to sketch in her sketchpad because the paper was ‘too nice’. I have met learners like this, they don’t want to mess up their sketchpad because it is expensive. The sketchpad needs to be the place you let go and experiment so if this is you then maybe a less good quality might be a better option initially.
Also see Which Sketchpad? for more advice on sketchpads and paper types.