Do I need a larger sd card to flash a custom rom?

[AC Question]

I asked this question on xda-developers last night and haven't gotten an answer, so I'll repost it here:
I'm trying to do my first custom ROM flash via CWM, but every time I've tried to backup it says I can't backup /data. I'm not sure if it may be related to a size issue? I have a 16gb phone with 6.21gb free, and a microSD with about 3.7gb free when formatted. If this is the issue, could I possibly backup to my PC? Also, is it normal to have 6.26gb of system memory used, and if not, how can I find out what's taking up the extra space?

 

[itguyjax8430]

I asked this question on xda-developers last night and haven't gotten an answer, so I'll repost it here:
I'm trying to do my first custom ROM flash via CWM, but every time I've tried to backup it says I can't backup /data. I'm not sure if it may be related to a size issue? I have a 16gb phone with 6.21gb free, and a microSD with about 3.7gb free when formatted. If this is the issue, could I possibly backup to my PC? Also, is it normal to have 6.26gb of system memory used, and if not, how can I find out what's taking up the extra space?

Welcome to Android Central!

You are definitely going to need more space for a backup. To give you an idea a backup size for me Note 4 is around 7GB. That includes all your user data, system file, and everything else. You are going to need to free up some space or get a larger SD card.