Hello. Thank you for your interest in our Ticking Stripe Black Standard Dining Chair Pads and for contacting us with your question. The dimensions are measured at the widest points of the chair pad. The most narrow part of the chair pad would be at the back near the ties. This point of reference does taper about 5" less than the width of the cushion. Our size standard dining chair pads are approximately 15"D x 17"W x 2.5"W. We hope this answered your question. Feel free to contact us if you have any further questions or concerns.