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AWS Certificate Manager
User Guide (Version 1.0)

Limits

The following AWS Certificate Manager (ACM) limits apply to each AWS region and each AWS account. To request higher limits, create a case at the AWS Support Center. New AWS accounts might start with limits that are lower than the limits described here.

ItemDefault Limit
Number of ACM Certificates100
Number of domain names per ACM Certificate10. See the information following this table.

Number of Domain Names per ACM Certificate

The default limit is 10 domain names per ACM Certificate. To request a higher limit, read the following information and then create a case at the AWS Support Center.

You cannot add or remove domain names from an existing ACM Certificate. Instead, you must request a new certificate with the revised list of domain names. When you do, you must validate ownership of all the domain names in the request, including the domain names that you previously validated for the original certificate. For each domain name in the request, you receive up to 8 validation emails, at least 1 of which must be acted upon within 72 hours.

For example, when you request a certificate with 5 domain names, you receive up to 40 validation emails, at least 5 of which must be acted upon within 72 hours. To add 4 more domain names to the certificate, you must request a new certificate with all 9 domain names, resulting in up to 72 emails, at least 9 of which must be acted upon within 72 hours. As the number of domain names in the certificate request increases, so does the work required to validate ownership of the domain names each time you want to make a change to the domain names in the certificate.

Before requesting an increase to the number of domain names allowed per ACM Certificate, consider the management overhead required to validate ownership of the domain names each time you want to make a change to the domain names in the certificate. You might find it easier to request a high number of certificates with only one or two domain names in each rather than request a low number of certificates with many domain names in each.