Things You'll Need
Crochet hooks in various sizes
Crocheted afghans can be made in every size. Most patterns specify this variable for the crafter, but you can customize an afghan yourself when instructions are lacking. The next time you find a crochet pattern for a lap-sized afghan you like -- but would rather have a bedspread -- don't scrap it and look for another one. Try out a pattern increase method instead. You may have to tinker with it a bit, but in the end, having a beautiful bedspread is worth the extra time.
Increase with Hook Size
Crochet a 4-by-4-inch sample of the pattern stitch with the hook that the pattern calls for. This is called a gauge swatch.
Choose a hook that is two to three sizes larger than the recommended hook. Crochet another sample exactly the same way that you crocheted the first one. The second square will be bigger.
Measure the second square. Subtract 4 inches from this measurement to get the amount that the sample increased. For example, if the larger hook gives you a width of 4 1/2 inches, then the square increased by 1/2 inch.
Calculate the amount that the pattern will increase with the new hook size. Divide the original pattern's width measurement by four. Multiply this new number by the amount that your square increased; for example, if the width was 32 inches, then 32 divided by 4 equals 8, and 8 times 1/2 inch equals 4 extra inches in width.
Subtract the width of the afghan your pattern will make -- from the typical width of a queen bedspread -- which is 121 inches. The resulting number, is the extra number of inches you will need in width. Continue to change hook sizes, until you find one that gives you the required number of extra inches -- keep in mind, that going from a small blanket to a bedspread using this method might require a large hook, which makes a loose fabric.
Begin crocheting the afghan using the hook that gives you the proper width. Continue to work the pattern until you reach the typical length of a queen bedspread, 102 inches. Try to end with a full pattern repeat so that the bedspread looks complete.
Increase with Pattern Repeats
Identify the stitch pattern repeat in the afghan pattern. This is normally located on the row after the foundation row or rows, between the asterisks, as in double crochet in next 15 stitches, three single crochet in next two chains, double crochet in next 15 stitches, skip one chain, repeat from .
Count the number of stitches needed to perform the repeat. For instance, in the example there are 33 foundation stitches that receive stitches -- 30 for the double crochet and three chains.
Perform a practice pattern repeat, then measure it, to get the width. Each pattern repeat you add to the afghan increases its width by this measurement.
Divide the typical width of a queen bedspread, 121 inches, by the width of your pattern repeat. The resulting number is the number of pattern repeats you need.
Crochet the foundation, adding the necessary number of repeats. Work the next row by repeating the pattern over the number of pattern repeats.
Continue to add rows until the bedspread reaches the typical queen bedspread length, 102 inches.
The larger the crocheted bedspread, the heavier it will be. Heavy crochet bedspreads may pull out of shape or be difficult to wash, so consider how much use the bedspread will get, and how often it will need to be cleaned, before resizing a pattern.