There is no additional charge for AWS Migration Hub. You only pay for the cost of the migration tools you use, and any resources being consumed on AWS.
For more details on AWS service and migration tool pricing, see the pricing section of relevant AWS services:
Additional pricing resources
AWS Pricing Calculator
Easily calculate your monthly costs with AWS
Economics Resource Center
Additional resources for switching to AWS
Start migrating today
Get started migrating with AWS Migration Hub on the AWS Management Console.