Fargate Pricing in Context | Trek10
Fargate costs more per GB of RAM and vCPU, however costs are directly metered off of provisioned container RAM & CPU (each variable is metered independently) and you are never paying for unused cluster capacity. Therefore the key variable in comparing Fargate pricing to EC2 is cluster reservation rate.
Theoretical cost optimization by Amazon ECS launch type: Fargate vs EC2 | Containers