Credit Usage
Tile Generation
1 credit per 1,000 tiles generated

Feature Services
2.4 credits per 10 MB stored per month

Tile and Data Storage
1.2 credits per 1 GB stored per month

Geocoding
80 credits per 1,000 geocodes

Data Transfer (Outbound)
6 credits per 1 GB

Service Credits Estimator

How Many Credits You Need For ArcGIS Online? The Service Credits Estimator Will Tell You