How to Use the Paper Tray Capacity Calculator
When refilling a printer or copier's paper tray, it's easy to either underfill it or jam it by cramming in too many sheets — especially if you don't know exactly how many sheets the remaining space can hold. This calculator converts your paper's basis weight into a sheet thickness estimate, then divides your tray's remaining height by that thickness to give you the maximum sheet count.
Basis weight (lb) is the weight of 500 sheets of a paper's uncut base size (17×22 in for Bond/Writing paper). Standard copy paper is 20lb (about 75 gsm), while cardstock and cover stock often run 65-110lb. The higher the basis weight, the thicker and stiffer the sheet — and the fewer sheets fit in the same tray height.
This calculation assumes an average paper density of about 0.8 g/cm³, so real-world results can vary slightly by manufacturer, coating, and humidity. Damp paper especially tends to swell, holding fewer sheets than the estimate. Leaving a bit of headroom instead of packing the tray to the brim helps prevent paper jams and misfeeds.
Frequently Asked Questions
Basis weight is the weight of 500 sheets of a paper's uncut base size, in pounds. For standard 20lb bond paper, that equals roughly 75 gsm — the higher the number, the thicker and stiffer the sheet.
Actual thickness varies by manufacturer, coating, and humidity, so this result is an approximation. Leave a little headroom in the tray instead of filling it to the very top.