Hello and a good day you!  I was just curious about the size of a sleeping pad one should purchase.  Is it a good idea to go wider than your sleeping bag or does it matter at all?  I was consider getting on that is 30 inches wide as opposed to 25 inches wide even though my sleeping bag is not that wide.  I am new to all of this. Please share any ideas or suggestions you may have.  Thank you and have a great day!

@Lanzastar  Is this pad for car camping or backpacking?  If for backpacking, you want as small and light as possible.  For car camping, weight is not as important, but excessive bulkiness should be avoided.

I have never needed a pad wider than my bag, but your mileage may vary.  Still, I don't think the wider pad is necessary.  The R value of your pad is probably much more important.

Superusers do not speak on behalf of REI and may have received
one or more gifts or other benefits from the co-op.

@Lanzastar If you are car camping then you can take anything you want...there are all kinds of cots and mattresses.

For backpacking, 20 inch wide pads are the norm and many lightweight two person tents are tapered towards the foot end such that when used by the nominal occupancy only 20 inch pads will not overlap at the foot end.  If you are primarily a back sleeper or of a larger persuasion you will probably prefer a wider pad to keep your elbows off the ground.   The pad I like is the Thermarest X-lite Regular Wide or the Large if you are taller.  These pads are nominally ~25 inches at the shoulders and taper towards the feet.  I don't know if two will fit but you can probably fit one if the other is a 20 inch pad in a typical UL2 type tent.  I actually have an X-lite Regular which works fine for me because I am generally a side sleeper.

It really it comes down to what you need to get you a good nights sleep. 

@Lanzastar ,

How wide the pad is (unless you are literally falling off the sides) is not as important as the R-value (how insulated it is) and the length. Try to get a pad that long enough so your feet will not fall off the end. If you are winter camping, try to get a sleeping pad that has an R-value above 5. Therm-a-Rest makes some great pads (air) but they are $$$. If you are on a tight budget, you could get an air pad with a lower R-value (look at Klymit) and then add an inexpensive closed-cell pad (see again Therm-a-Rest).