How many photos will fit on my memory card?

When taking photos with a digital camera it is useful to know how many photos will fit on your memory card (SD, Memory Stick Duo, USB, etc), and know how large the JPEG images are.

There are a lot of tables out there showing this kind of information. I don’t trust other people’s numbers so I decided to calculate them myself and produce some charts to show how the number of megapixels you use when taking the photo affects how many photos will fit on the card.

MP 0.3 1 2 3 4 5 7 10 12 15
256MB 1896 569 284 190 142 114 81 57 47 38
512MB 3793 1138 569 379 284 228 163 114 95 76
1GB 7585 2276 1138 759 569 455 325 228 190 152
2GB 15170 4551 2276 1517 1138 910 650 455 379 303
4GB 30341 9102 4551 3034 2276 1820 1300 910 759 607
8GB 60681 18204 9102 6068 4551 3641 2601 1820 1517 1214

The table above is what I came up with. I made the assumption that the images are stored as JPEGs and the compression ratio is 15:1. That is a rough average of what my Sony Cyber-shot W80 camera is compressing my photos at.

The compression ratio can have a big effect on the size of your photos. It can for example make the difference between your photo being 2MB in size or being 4MB in size.

This graph shows the JPEG photo size when using low compression (which I’m defining as 10:1) and high compression (which I’m defining as 20:1).

size of jpeg photos vs megapixels

My second graph shows how many photos you can fit on a 4GB card. I chose 4GB as this is quite a typical memory card size for today’s digital cameras. You can see that a small decrease in the megapixel resolution (that you shoot the image at) can allow you to fit a lot more photos on the card.

how many photos will fit on a 4gb memory card

Here’s a table of the average JPEG image sizes for differing megapixel resolutions.

MP 0.3 1 2 3 4 5 7 10 12 15
Size (MB) 0.14 0.45 0.9 1.35 1.8 2.25 3.15 4.5 5.4 6.75

If you take a lot of photos then I’d recommend you try decreasing the number of megapixels in your photos. Most digital cameras will allow you to do this very easily. Today 10MP and 12MP cameras are common, but this level of detail is way more than most people need. Megapixels are a marketing game played by camera manufacturers.

By having the resolution too high you are just decreasing the amount of pictures you can take, increasing the space they use on your computer, and increasing the time it takes to process or upload them.

I have a 7MP camera. I have turned it down to 5MP because I find 5MP to be sufficient. You get great photos at 5MP – they look great on screen and great when they are printed out on 6×4 inch or 7×5 inch photo paper.

Give it a go, and see if you notice any difference.

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