What is Duplex Printing?

Most home printer users accept the fact that they can only print on one side of a page. If they need to print on either side of a sheet of paper, they re-insert the pages into the printer (carefully, making sure that the sheets are facing the right way and the right direction) and then print the second side.

This is fine for limited uses -- for example, if you're making some greeting cards, or doing a limited amount two-sided printing. But if you do a lot of printing on both sides of your paper, and you're getting tired of fussing with piles of printed paper, then you may want to consider a printer that does it for you.

Printing on both sides of a sheet of paper is known as double-sided, or duplex, printing. (Printing on one side is single-sided, or simplex.) Printers capable of double-sided printing usually have an internal tray that catches the paper after the first side is printed, flips it, and runs it through the print cycle again.

This mechanism can also be called a Reversing Automatic Document Feeder (RADF).

A few printers have RADFs that are external, and can be added after you buy the printer, but for the most part, you need to opt for the duplex feather at the time of purchase. (You may see printer specs that say it has "manual" duplex printing -- all that means is that you get to reverse the paper yourself, but that the software will track what to print on each side of the page.)

If you do a great deal of duplex printing, printers with RADF can save you an enormous amount of time. However, you probably shouldn't consider one unless you are using one in a professional capacity -- in a business, say. Equipping a printer with duplex capabilities adds quite a bit to its price -- enough so that most are out of the range of home users. For example, HP's LaserJet 4200dtn printer, a 35ppm black-and-white laser printer which includes duplex printing and can also be attached to a network, has a list price of about $2,000, while the same printer without duplex costs about $1,730, a difference of $270.