How big is a 4-gallon slow cooker in quarts?

Four gallons is about 15 to 16 quarts. That is roughly three to four times a standard 6-quart family cooker, so plan on counter and storage space for it.

Is this slow cooker programmable?

Yes, it is sold as a programmable model, which usually means a digital timer and selectable heat settings rather than a single dial. Confirm the exact control layout on the unit you receive.

Can I use it for a family of four?

It will work, but it is oversized for everyday meals. A 6- to 8-quart cooker is easier to handle and gives better results for small batches.

Does the glass lid help?

Yes. You can check progress without lifting the lid, which keeps heat and moisture in. Glass lids are heavier and more fragile than plastic ones.

Is it dishwasher safe?

The stoneware insert and glass lid on most slow cookers of this type are dishwasher safe, but the heating base is not. Check the manual that comes with your unit before washing.