There is no set number. If you shoot colorful subjects like I do (orchids) you blow through ink faster than your typical vacation/kids/pets shots. If you print out sunrises/sunsets, you can expect to blow through red and yellow faster than blue. I have gotten as many as 30 letter-sized photos with lots of saturated color from one set of XL cartridges. 4x6 photos use up way less ink and you can sometimes get 60 photos or more, but it always depends on how saturated you want your colors to be. I take all my shots through Photoshop and that tends to give me beautiful prints, but less quantity (but stellar quality). Expect to use more of one or two colors, so make sure you always have a set of backup cartridges. I used to print with the big 6-color HP and got more photos, but the extra cartridges end up costing more money.