Top-up limits depend on the bank you are using and may vary or change based on bank policies.
Current per-transaction limits are:
ADIB: up to AED 5,000 per transaction
CBD: up to AED 5,000 per transaction
Mashreq: up to AED 50,000 per transaction
Wio: up to AED 49,900 per transaction
FAB: up to AED 10,000 per transaction/daily limit
Your Ziina account limits also apply to top-ups. If your account's limit is lower than your bank's, the lower limit applies. You can check your account limits here: