What size cash drawer to buy
When looking to buy a new cash drawer there are several factors to look at the most important being "will the cash drawer work with my software". In most cases if your using a receipt printer then a printer driven cash drawer will work with your software. Either the software will send the open command when the printer is printing a receipt or the receipt printer drivers can send the control characters to open the drawer every time it prints.
Outside of that the next most common question is "What size drawer do I want?" When looking at the listings like the APG Vasario or POS-X Ion Cash Drawer, your going to notice a few differences with the biggest being that the drawers are available in two different sizes. So what size is preferable? Well it depends on your setup and if you want things on top of the drawer. In traditional grocery lane setups the cash drawer was the platform that the computer, monitor, receipt printer, and keyboard would sit on, so in order to fit all those things nicely you had to get a large format drawer, typically 19 x 19 or more. As time went on and both computers and monitors got smaller it has become exceedingly easier to fit more things on a smaller space so 16 x 16 drawers have become a lot more popular. However there is one thing to note. A keyboard with a 10 key pad is normally 18" or more wide, so if you go with a compact drawer then the keyboard won't fit on top. You normally can't put the keyboard in front of the drawer either because then you block the drawer from opening.
One solution is to mount your cash drawer under the counter with "under counter mounting brackets", then you can have your drawer open without hitting the keyboard, lots of room for your POS Accessories and the computer, and go with the smaller sized drawer. You will have to have the ability to drill into your counter to mount the brackets and make a hole to run the cash drawer cable to. But overall it is a good option for those that want to hide their drawer.
One other note on the size is how many coins and bills the drawer holds. 16" x 16" and 18" x 18" drawers both have 5 bills and at least 5 coin slots. But sizes below that like the APG 14" x 16" manual cash drawer, will only have four bill slots.