Calculate disk space for Encryption at rest

We are planning to implement Encryption at rest using WiredTired Storage Engine
https://docs.mongodb.com/manual/core/security-encryption-at-rest/

What is the percentage of disk space increase that would be required to account for after the encryption .
I am aware the Encryption at rest is wrapper for the Entire DB volume and the individual collections and fields are not encrypted as such …

Should the disk space increase ( if it does) be any concern for Encryption at rest

Similarly for Field level encryption , what is percentage of additional disk space that need to be accounted for ( For Eg : for a 1TB Mongodb Database)

Thanks