Determining the ideal size of tablecloth is a quick and simple process, and instructions are included below that will help you decide how low your tablecloth should extend. Even if your table is an unusual shape, you can typically measure it either as a circle or a rectangle, depending on whether its length and width are roughly equal or significantly different.
Measuring a Square, Rectangular, or Oval Table
Extend or shrink the table to the size it will typically be when you use the tablecloth. If your table has removable leaves or attachments that can be used to alter its size, decide what size best suits your purposes. If you want a day-to-day tablecloth, keep the table at the size you use for normal purposes. If you are looking for a formal tablecloth to use when entertaining guests, you may wish to measure the table when it is extended to its maximum size.
If you want one tablecloth that will fit your table at any size, measure the table at its largest size and select a tablecloth that will hang no more than 6 inches (15cm) over the edge. Be aware that the tablecloth may look uneven when the table is at a smaller size.
Measure the table length. Use a tape measure to measure the table along its longest direction, or along either direction for a square table. Measure directly in the center of the table, not along one of the outer edges, especially if your table is oval in shape.
Write down your measurements as you make them to avoid forgetting them.
Measure the width of your table. Measure the other horizontal dimension of the table, at right angles to the first. As before, measure near the center of the table. It doesn't hurt to make this measurement even if your table appears square; it can sometimes be difficult to tell a square and rectangle apart.
Determine how far you'd like your tablecloth to hang down. The length a tablecloth hangs below the surface is called the drop length. Most dining room tablecloths have a drop length between 6 and 12 inches (15–30 cm), no further than diner's laps. A more formal dining tablecloth may reach all the way to the ground, as will a tablecloth intended to hide unattractive table legs.
To help you visualize which drop length you prefer, hold a piece of fabric or paper hanging downward from the table's edge. Place your chairs and other nearby furniture objects where they would be located on occasions when you would use this tablecloth.
Calculate the length and width of your tablecloth. Multiply your desired drop length by two, since the tablecloth will hang from both ends of the table. Add this result to your table's length to get your tablecloth's ideal length, and to your table's width to get your tablecloth's ideal width.
If your table is oval, you may purchase either an oval or rectangular tablecloth with these measurements.
Get a slightly larger tablecloth if you cannot find the exact size. If you cannot find a tablecloth that fits your table's exact dimensions, and you are not interested in purchasing or making a custom tablecloth, use a tablecloth that's slightly larger than your measurements. A larger tablecloth will simply hang lower, while a smaller one may not cover the entire table. Also, as with any fabric, tablecloths may shrink when washed, potentially becoming up to 4 inches (10cm) smaller over time.
You may also consider alternative options, such as a rectangular "runner" cloth that runs across the center of a rectangular table without covering the full width.