Opacity
How see-through is the photo paper? The higher the opacity, the lesser will be the printed text and images bleed through to the other side. This is especially important for double-sided printing. Inkjet photo papers have a relatively high opacity, usually between 94-97% as compared to ordinary inkjet or laserjet papers; so bleed-through is less of an issue.

Brightness
How white is white? Generally, paper have many different levels of whiteness or brightness. Brightness can be expressed as a number between 1 to 100.  Photo papers are usually rated in the high 90s. Not all papers come labeled with their brightness rating. The best way to determine the brightness is simply to compare two or more papers side-by-side.

Weight
Paper weight is usually expressed in pounds (lb.) or as grams per square meter (g/m2). Different types of paper have their own weight scale. The bond papers which include most inkjet photo papers are between 24 to 71 lb. (90 to 270 g/m2) range. Terms like ¡°heavyweight¡± do not necessarily indicate a heavier paper.

Caliper
Photo papers are heavier and thicker than most multi-purpose papers. This thickness, known as caliper, is necessary to accommodate the greater ink coverage typically found in photos. Typical inkjet paper caliper may be anywhere from a thin 4.3 mil to a thick 10.4 mil paper. Photo paper is usually 7 to 10 mils.

Glossy Finish
The coating on photo papers gives your printed photos the look and feel of photographic prints. Because the coating keeps the paper from readily absorbing the ink some glossy papers dry slowly. However, quick-dry gloss finishes are common today. The finish may be described as high gloss, gloss, soft gloss, or semi-gloss; each reflecting the amount of shine. Satin is a less shiny coated finish.

Matte Finish
Images printed on photo matte papers appear soft and non-reflective, not shiny. Matte finish papers are not the same as regular inkjet finish papers. Matte finish photo papers are thicker and are specially formulated for photos. Many matte finish papers are printable on both sides.