| Instance Type | vCPU | Max NIC | Recommended BYOL License | | :--- | :--- | :--- | :--- | | Standard_DS1_v2 | 1 | 2 | FG-VM01 or FG-VM01v | | Standard_DS2_v2 | 2 | 2 | FG-VM02 or FG-VM02v | | Standard_D2s_v3 | 2 | 2 | FG-VM02 or FG-VM02v | | Standard_DS3_v2 | 4 | 4 | FG-VM04 or FG-VM04v | | Standard_D8s_v3 | 8 | 4 | FG-VM08 or FG-VM08v | | Standard_DS5_v2 | 16 | 8 | FG-VM16 or FG-VM16v |
Always perform a full configuration backup of your FortiGate VM.
FortiGate VM Sizing in Azure: A Comprehensive Guide for 2026 fortigate vm sizing azure
1. Define required throughput (clean traffic) → ______ Gbps 2. Multiply by 1.5x (future growth) → ______ Gbps 3. Add inspection factor: - No inspection: x1.0 - Basic firewall + NAT: x1.2 - +IPS: x1.5 - +SSL inspection: x2.0 → Effective required Gbps = ______ 4. Match to Azure VM size from table in section 3 5. Check license SKU supports that throughput 6. Add 20% vCPU/RAM overhead if using: - SSL deep inspection - 50+ IPsec tunnels - Explicit web proxy 7. Final VM size = ______
When selecting your size in the Azure Marketplace, keep these three technical limits in mind: | Instance Type | vCPU | Max NIC
More interfaces allow for better traffic segmentation but require larger instances. 2. Choosing the Right Azure VM Family
Use or Ultra Disks to prevent disk I/O bottlenecks. Slow disk write times can cause backpressure on the logging daemon, leading to elevated system memory utilization and triggering FortiOS "Conserve Mode." 6. Verification and Monitoring Strategy Multiply by 1
Properly sizing your FortiGate-VM on Azure is a multi-faceted process that goes beyond simply choosing a virtual machine size. By understanding the interplay between BYOL licensing and Azure VM instances, using the official sizing and performance tools, planning for high availability, and being aware of common pitfalls, you can build a security architecture that is both powerful and cost-effective.
Always check the Azure VM Network Bandwidth limits before selecting a size.
High traffic volumes with many simultaneous connections require more RAM. 2. FortiGate VM Licensing & Azure Instance Matching