Simple question really…

…how many images can I get onto a memory card?

Well, ok, at first sight, it seems very simple – divide the capacity of the card by the size of the image files and hey presto!

Except no – you can’t just do this. For a start, despite the fact that cards are shown with a capacity in Giga bytes (or Giga octets) this number needs to be modified.

A single gigabyte is in fact 1024 Megabytes of space. So now we multiply the indicated card capacity by 1024.

For a 128Gb card : 128 * 1024 = 131072 Mb

Now take of up to 7% of this space for the directories and space needed by the car to reference everything written on to it and we’re left with

131072 – 7% (9175 Mb) = 121896 Mb

Now we can take our ‘average’ file size (I estimate 33Mb for my 24 megapixel sensor – this changes with file type RAW or JPEG, compression, loss or lossless, 12 or 14 bit etc. and also the detail in the image…)

121896 / 33 = 3693 images

According to the official NIKON manual for the Z6ll I should be able to record 2400 image files on a 128Gb card – this calculation (confirmed by other sites) indicates a 30% increase…

I’m off to the Highlands in the fall – with a bit of luck, and a 512Gb memory card, I won’t even need to do a backup while I’m away. But, of course I will as I don’t trust ANY memory card system, and a simple download to my NVMe backup will reassure me 🙂

PS The answer seems to be « in excess of 14,000 images on a 512Go card »


Interestingly, I posted this question on the NIKON RUMURS forum – naturally no-one has responded (the people there don’t actually own any cameras to make images, so they’re incapable of knowing how many ‘virtual’ images they would be able to get on their ‘virtual’ memory cards).

I also mailed Thom Hogan – and received a reply – I rest my case. If you need information, go to the pros – thanx Thom.

Further Update

It seems the answer was in fact hiding in plain sight…

Here’s the control panel of one of my NIKON cameras and even switched off it displays how many (approximately) images can be stored on the card (in this case a 512Gb)

Sometimes you can’t see the wood for the trees…..