what is the biggest SSD I can put into a Mid 2010 Macbook Pro?

There might be a maximum capacity, but I believe it's well beyond anything that's currently available. I believe the main drive bay should be able to accommodate at least 11.5 mm thickness.

The highest capacity I've heard of is the Samsung EVO 860 4TB.

SSD 850 EVO 2.5" SATA III 4TB Memory & Storage - MZ-75E4T0B/AM | Samsung US

Frederic Chiu wrote:

What is the biggest size SSD I can put into my machine? I'm guessing that technology and Moore's Law has made SSDs more spacious for the same size.

Just FYI - Moore's Law was generally about transistors per unit area. However, for flash memory, the thing that has increased capacity per unit area is 3D (stacked) layers and tri-level (3 bits) cells.

Besides that, if you ever looked inside a SATA SSD, there's actually a lot of wasted space. The board and ICs barely take up any space at all. The integral SSDs on the new MBPs barely take up any volume. They're not SATA, but there are some enterprise-class SSDs in a similar size as SATA that are 30-50 TB.

Frederic Chiu wrote:

Thank you so much for the links. Am I correct in understanding that there is no compatibility issue with these huge drives, as long as it fits into the physical space? i.e. the computer will be able to use all 4-6T, there won't be issues with referencing all the memory?

It shouldn't be a problem. The only thing is the cost. If you really want that 8 TB SSD, it's yours for a cool $2700 (USD).

OK - found something even higher capacity.

https://www.cdw.com/product/Micron-5100-solid-state-drive-7680-GB-SATA-6Gb-s/478 6008

Since MacOS 10.4, the drive size limit using GUID partition Map is larger than 8,000 Terabytes.

Any modern SSD drive you can buy, that fits in the space, will work fine.