This is from the Delta Web Site:
Carry-on Baggage
Our goal is to provide a convenient and comfortable trip and help everyone get on and off the plane quickly so you can be on your way.
You may bring one carry-on bag and one personal item onboard at no charge, plus one extra smaller item like a coat or umbrella. All items must meet the size requirements for carry-on baggage, so they can easily fit into the overhead bin or under the seat in front of you.
Approved Personal Carry-on Items
1 purse, briefcase, camera bag, or diaper bag;
or 1 laptop computer (computers cannot be checked and must be carried on);
or 1 item of a similar or smaller size to those listed above.
All carry-on items must be easily stored in the overhead bin or under the seat in front of you.
Additional Approved Carry-on Items
A couple of other items are okay to bring onboard. They do not count toward your personal items. Keep reading.
To be prepared for any kind of weather, you may bring a coat, jacket, or umbrella.
Enjoy food or drink purchased after clearing the security checkpoint.
Go ahead and shop. One box or bag of duty free merchandise is allowed.
A special item like a stroller, child restraint seat, or assistive devices such as wheelchairs or crutches.
Carry-on Items: Baggage Size and Weight Restrictions
When oversized bags don't fit in the overhead bins, delays happen. Fees will also be applied to the oversized bag if it has to be checked. In order to avoid delays as well as fees, follow these size and weight requirements:
Baggage may not exceed 45 linear inches (length+width+height) or 115 cm.
Baggage must fit easily in our SizeCheck® unit (approximately 22"x14"x9" or 56x36x23 cm).
Fees apply if your bag is too large to carry on and has to be checked at the gate.
Good Luck all.
Joe