Hm I tried it several time and the maximum approval amount stays the same even so I have charged 1+k already. So I would guess it is the total amount of all your charges?

Amex Platinum (NPSL) | Amex BCE (12,000) | Discover IT (8,000) | Chase Freedom (4,000) | Walmart (850) | Alliant CU Visa | CapOne Newcomers MC | Gone for good: CapOne secured (thx for getting me started) | Amex Zync (thx for getting me into AX)

FICO: TU 726 (5/13) EQ 694 (5/18) EX 714 (1/26)