A twin comforter typically measures 66 to 68 inches in width and 86 to 88 inches in length. The exact dimensions may vary depending on the brand, so its important to check the specific measurements before purchasing a comforter. Twin XL comforters are also available, which have the same width as a regular twin comforter but with an added length of 5 inches, measuring 68 inches in width and 90 inches in length.