These virtual machine sizes are a previous generation series. While older VM sizes are supported until further notice, we recommended using newer generations for improved performance and security. Check out the sizes overview's list of VM size families by type for a selection of newer sizes.
The B-series VMs can be deployed on various hardware types and processors, so competitive bandwidth allocation is provided. B-series run on the third Generation Intel® Xeon® Platinum 8370C (Ice Lake), the Intel® Xeon® Platinum 8272CL (Cascade Lake), the Intel® Xeon® 8171M 2.1 GHz (Skylake), the Intel® Xeon® E5-2673 v4 2.3 GHz (Broadwell), or the Intel® Xeon® E5-2673 v3 2.4 GHz (Haswell) processors. B-series VMs are ideal for workloads that don't need the full performance of the CPU continuously, like web servers, proof of concepts, small databases, and development build environments. These workloads typically have burstable performance requirements. To determine the physical hardware on which this size is deployed, query the virtual hardware from within the virtual machine. The B-series provides you with the ability to purchase a VM size with baseline performance that can build up credits when its using less than its baseline. When the VM has accumulated credits, the VM can burst above the baseline using up to 100% of the vCPU when your application requires higher CPU performance.
Base CPU performance, Credits, and other CPU bursting related info
Size Name
Base CPU Performance of VM (%)1
Initial Credits (Qty.)
Credits banked/hour (Qty.)
Max Banked Credits (Qty.)
Standard_B1ls
5%
30
3
72
Standard_B1s
10%
30
6
144
Standard_B1ms
20%
30
12
288
Standard_B2s
20%
60
24
576
Standard_B2ms
30%
60
36
864
Standard_B4ms
22.5%
120
54
1296
Standard_B8ms
17%
240
81
1994
Standard_B12ms
17%
360
121
2908
Standard_B16ms
17%
480
162
3888
Standard_B20ms
17%
600
202
4867
CPU Burst resources
1The base CPU performance metric hasn't changed. The updated (2024) numbers were normalized using a 0 – 100% scale. Previously, the scale was 0 – (vCPU x 100%).
B-series VMs can burst their disk performance and get up to their bursting max for up to 30 minutes at a time.
1Temp disk speed often differs between RR (Random Read) and RW (Random Write) operations. RR operations are typically faster than RW operations. The RW speed is usually slower than the RR speed on series where only the RR speed value is listed.
Storage capacity is shown in units of GiB or 1024^3 bytes. When you compare disks measured in GB (1000^3 bytes) to disks measured in GiB (1024^3) remember that capacity numbers given in GiB may appear smaller. For example, 1023 GiB = 1098.4 GB.
Disk throughput is measured in input/output operations per second (IOPS) and MBps where MBps = 10^6 bytes/sec.
1Some sizes support bursting to temporarily increase disk performance. Burst speeds can be maintained for up to 30 minutes at a time.
Storage capacity is shown in units of GiB or 1024^3 bytes. When you compare disks measured in GB (1000^3 bytes) to disks measured in GiB (1024^3) remember that capacity numbers given in GiB may appear smaller. For example, 1023 GiB = 1098.4 GB.
Disk throughput is measured in input/output operations per second (IOPS) and MBps where MBps = 10^6 bytes/sec.
Data disks can operate in cached or uncached modes. For cached data disk operation, the host cache mode is set to ReadOnly or ReadWrite. For uncached data disk operation, the host cache mode is set to None.
Expected network bandwidth is the maximum aggregated bandwidth allocated per VM type across all NICs, for all destinations. For more information, see Virtual machine network bandwidth
Upper limits aren't guaranteed. Limits offer guidance for selecting the right VM type for the intended application. Actual network performance will depend on several factors including network congestion, application loads, and network settings. For information on optimizing network throughput, see Optimize network throughput for Azure virtual machines.
To achieve the expected network performance on Linux or Windows, you may need to select a specific version or optimize your VM. For more information, see Bandwidth/Throughput testing (NTTTCP).
Accelerator (GPUs, FPGAs, etc.) info for each size