Apple and Google offer free cloud storage for your photos, but is the free amount enough? How many photos can you store in 5GB or 15GB of cloud space? When should you pay for more storage? Photo services offers multiple packages, so we did the legwork for you to find out how many photos you can store in Google Photos, Apple iCloud, Flickr, Dropbox, and several other services.

We're estimating that the average photo is 3MB. But photo file size depends on a few factors, including your phone's camera and the image type. Read on to learn more about image size, or jump ahead to find out how many photos each service will let you store.

Photo size: megapixels and image type

How big is a photo file? The first factor is your phone's camera. Different phone cameras have different amounts of megapixels. Megapixels are a measure of the image resolution -- the more megapixels, the larger the image's file size, generally.

For example, the rear-facing camera on the Samsung Galaxy S6 captures 16-megapixel images. The iSight rear-facing camera on the iPhone 6S and SE captures 12 megapixels, as does the Samsung Galaxy S7's camera. If you shoot with a DSLR camera, you may be capturing 20-, 30-, even 50-megapixel images.

The second factor is image type. Some images, such as high-definition photos, take up a lot more space. The iPhone 6's Live Photos can be two to three times larger than a regular image. An HDR photo -- really a combination of two or more images -- can eat up more storage.

How many regular-sized photos can you store in the cloud?

Let's assume you're capturing regular images, no HDR or Live Photos. CNET estimates that a normal image captured on the iPhone 6S averages 3MB. We captured a bunch of normal images on a Samsung Galaxy S6, both indoors and out, and found ours were about the same size.

So Apple's free 5GB of storage will hold roughly 1,667 3MB photos, and the paid 50GB tier will house about 16,000 images.

Google's free 15GB will store 5,000 photos, and its 100GB paid tier will hold approximately 33,000. (Google offers 15GB for photos stored at original size, and unlimited storage for photos using Google's high-quality compression setting. At the high-quality setting, photos under 16 megapixels are untouched, while photos larger than 16 megapixels are compressed. The 15GB includes everything stored across Google Drive, Gmail, and Google Photos.)

Flickr's roomy 1TB will store roughly 333,000 3MB photos.

Cloud Storage for Photos Chart
Clifford Colby follows the Mac and Android markets for He's been an editor at Peachpit Press and a handful of now-dead computer magazines, including MacWeek, MacUser, and Corporate Computing.