Here is the rest of the details from my developer on the project- What was our specific server size and setup and costs with RDS? We were using db.t3.medium

Here is the rest of the details from my developer on the project- What was our specific server size and setup and costs with RDS? We were using db.t3.medium (1 CPU, 2 vCPU, 4GB RAM), we were using a DB cluster that has 2 instances db.t3.medium overall cost (~$118 monthly) And now with EC2? We are using c5d.xlarge (4 CPU, 20 ECU, 8GB RAM), we are using one instance c5d.xlarge overall cost (~$140 monthly) What was the big cost savings? Our main issue was in I/O (Read and write), we have very high I/O demand so we was paying for I/O and storage (~$600) and the second issue is CPU credit (~$90 monthly) so the total save is ($600+$90+$118)-$140= $668 per month. Also EC2 performance is better than RDS because we get a very good cheaper than RDS server. Note: RDS is configuration less and has support while if you want to use EC2 then you need a person to do configuration and support for DB on it.