I am thinking about getting some tarp as a 1-person shelter for hiking this summer. There is a large choice of tarps on the market. The difference between them are often the size and the material it is made of, which influences the weight. And for similar prices, there are sometimes particularly light but smaller tarps.
I am therefore wondering what size I should pick my tarp. I took a piece of paper to draw triangles and calculate hypothetical dimensions with Pythagorean theorem. However that does not help me so much, because I have few ideas of how high I should expect my shelter to be, or how wide.
I suppose that sitting under the shelter requires a height of about 1 meter (~3 feet), and the width to sleep should be between 50cm and 1m (~2 to 3 feet) (which is a very wide difference). I also suppose that the length (on the ground) should be about 2,2m (7 feet, I am 1,90m - 6'3" - tall). I expect to have three sides touching the ground and one being hung up by a pole.
I ended up with some surface of 2.2m x 2.4m with these hypotheses, but I am not sure at all that is reasonable, as that does not include any margin and that matches more 2-person tarps on the market.
Does anyone have an experienced, better built idea of how to set up a shelter and therefore estimate the need for a tarp?