Azure SQL Database cost calculator

Pick vCore for any workload that will live longer than a year. vCore is the only tier that supports Hybrid Benefit and Reserved Capacity, the two stacking discounts that take 60 to 80 percent off published rates. DTU is fine for small workloads under $200 per month where the discount math does not move the needle. Above that, DTU is leaving money on the table every month.

Hyperscale separates compute from storage and prices each independently. Storage starts at $0.10 per GB per month, no upper bound, scales to 100 TB. Compute is per primary replica, plus optional read replicas. The break-even versus General Purpose is around 1 TB. Above 4 TB, Hyperscale is the only sensible answer. Below 200 GB, General Purpose with AHB and 3-year Reserved is cheaper.

Cleanly. AHB removes the SQL Server license component. Reserved Capacity discounts the compute component. Both apply at once. On a typical 8-vCore General Purpose database, AHB saves roughly $1,500 per month, and a 3-year Reserved on top of that saves another $1,000 per month.

Yes if you have ten or more databases with non-overlapping peak loads. The pool sizes for the aggregate worst case rather than the sum of every database peak. The trap is putting databases with synchronized peak loads in the same pool, where the math breaks even or worse.

Rarely. Business Critical adds local SSD, three replicas, in-memory OLTP, and Always On read replicas at roughly 2.7x the General Purpose rate. If query latency on General Purpose is under 50 ms p99 and CPU is the bottleneck, Business Critical does nothing for you.