How do I measure the dimensions of an aluminum sheet to purchase?

To measure the dimensions of an aluminum sheet for purchase, first, ensure you have a measuring tape or a ruler. Measure the length and width of the sheet from one corner to the opposite corner, making sure to measure along the longest and widest sides. Record these measurements in the same unit of measurement used by the supplier (commonly inches or centimeters). If the sheet is not a perfect rectangle, measure the diagonal to confirm the dimensions. Note any irregularities or variations in thickness that might affect the intended use. Once you have these measurements, compare them with the available options from the supplier to select the appropriate size.