Sustained use discounts

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Compute Engine offers sustained use discounts (SUDs) on resources that are used for more than 25% of a billing month and are not receiving any other discounts. Whenever you use an applicable resource for more than a fourth of a billing month, you automatically receive a discount for every incremental hour that you continue to use that resource. The discount increases incrementally with usage and you can get up to a 30% net discount off of the resource cost for virtual machine (VM) instances that run the entire month.

Sustained use discounts apply to the following resources:

Compute Engine offers a maximum monthly SUD percentage of either 20% or 30% depending on the resource and machine types. The following table shows the list of resources that are eligible for each SUD percentage:

Maximum of 20% monthly SUDs Maximum of 30% monthly SUDs
  • All general-purpose N2 and N2D predefined and custom machine types
  • All general-purpose N2 and N2D sole-tenant node types
  • All compute-optimized C2 machine types
  • All compute-optimized C2 sole-tenant node types
  • All general-purpose N1 predefined and custom machine types
  • All general-purpose N1 sole-tenant node types
  • All memory-optimized M1 and M2 machine types
  • All memory-optimized M1 and M2 sole-tenant node types
  • f1-micro and g1-small shared-core machine types
  • All GPU devices with the exception of NVIDIA A100 GPU types

Sustained use discounts are calculated and applied automatically to usage within a billing account, so there is no action required on your part to enable these discounts.

Limitations

  • Sustained use discounts automatically apply to VMs created by both Google Kubernetes Engine and Compute Engine.

  • Sustained use discounts do not apply to VMs created using the App Engine (standard and flexible) environments and Dataflow.

  • Sustained use discounts do not apply to E2, A2, M3, Tau T2D, or Tau T2A machine types.

Sustained use discounts at different usage levels

To take advantage of the full discount, create your VM instances on the first day of the month. Discounts reset at the beginning of each month.

The following tables describe the discount you get at each usage level of a VM. These discounts apply for all machine types but don't apply to preemptible VMs.

Sustained use discounts for up to 30%

The following table shows the SUDs breakdown per usage level for the resources that receive a maximum monthly discount of 30%:

Resources Usage level (% of month) % at which incremental is charged Incremental rate (USD/hour)
example: n1-standard-1 VM
All N1 predefined and custom machine types,
All N1 sole-tenant node types,
All M1 and M2 machine types,
All M1 and M2 sole-tenant node types,
f1-micro and g1-small shared-core machine types,
All GPU devices with the exception of NVIDIA A100 GPU types
0%–25% 100% of base rate $0.0475
25%–50% 80% of base rate $0.0380
50%–75% 60% of base rate $0.0285
75%–100% 40% of base rate $0.0190

Sustained use discounts for up to 20%

The following table shows the SUDs breakdown per usage level for the resources that receive a maximum monthly discount of 20%:

Resources Usage level (% of the month) % at which incremental is charged Incremental rate (USD/hour)
example: c2-standard-4 VM
All N2 and N2D predefined and custom machine types,
All N2 and N2D sole-tenant node types,
All C2 machine types,
All C2 sole-tenant node types
0%–25% 100% of base rate $0.2088
25%–50% 86.78% of base rate $0.1811
50%–75% 73.3% of base rate $0.1530
75%–100% 60% of base rate $0.1252

Sustained use discounts are applied on incremental use after you reach certain usage thresholds. This means that you pay only for the number of hours that you use a VM, and Compute Engine automatically gives you the best price. There's no reason to run a VM for longer than you need it.

The following graph shows how your effective discount increases with use, up to 30%:

Click to enlarge

For example, if you use a virtual machine for 50% of the month, you get an effective discount of 10%. If you use it for 75% of the month, you get an effective discount of 20%. If you use it for 100% of the month, you get an effective discount of 30%. You can also use the Google Cloud Pricing Calculator to estimate your sustained use discount for any arbitrary workload.

Applying sustained use discounts

Consider a scenario where you have two VMs or sole-tenant nodes in the same region that have different machine types and run at different times of the month. Compute Engine breaks down the number of vCPUs and amount of memory used across all VMs that use predefined machine types and combines the resources to qualify for the largest sustained usage discounts possible.

Assume you run the following two VMs in the us-central1 region during a month:

  • For the first half of the month, you run an n1-standard-4 VM with 4 vCPUs and 15 GB of memory
  • For the second half of the month, you run a larger n1-standard-16 VM with 16 vCPUs and 60 GB of memory

In this scenario, Compute Engine reorganizes these machine types into individual vCPU and memory resources and combines their usage to create the following resources:

  • 4 vCPUs for a full month
  • 12 vCPUs for half of the month
  • 15 GB of memory for a full month
  • 45 GB of memory for half of the month

For example, you can see how the sustained use discounts apply to the vCPUs for this scenario:

How vCPUs from VMs are combined using resource-based sustained use discounts for predefined machine types.

The monthly bill for these resources would be calculated using the following formulas:

(4 vCPUs x $0.031611 x 730 hours) x 0.7 for the 30% full-month discount = $64.612884

(12 vCPUs x $0.031611 x 365 hours) x 0.9 for the 10% half-month discount = $124.610562

(15 GB x $0.004237 x 730 hours) x 0.7 for the 30% full-month discount = $32.476605

(45 GB x $0.004237 x 365 hours) x 0.9 for the 10% half-month discount = $62.6334525

The total monthly cost of the combined resources is $284.3335035.

Compare this total to the previous way that sustained use discounts would have been calculated for these same predefined machine types. For example, you can see how the vCPUs are billed when they are inferred by machine type rather than combined by resource types:

How VMs were previously inferred using machine-type sustained use discounts.
(1 n1-standard-4 machine x $0.189999 x 365 hours) x 0.9 for the 10% half-month discount = $62.4146715

(1 n1-standard-16 machine x $0.759996 x 365 hours) x 0.9 for the 10% half-month discount = $249.658686

The two VMs are not inferred because they are different machine types, so their total monthly cost is $312.0733575.

With the new pricing changes, you save an additional $27.739854 in this usage scenario. This same process applies separately to the resources for custom machine types.

Sustained use discounts for GPUs

For GPU devices, Compute Engine calculates sustained use discounts based on the number of a GPU model that you have attached to running VMs during the month. You can receive sustained use discounts only on GPUs of the same model. Sustained use discounts for GPUs are calculated separately from VM machine type, vCPU, and memory discounts.

For example, consider a scenario where you have two VMs with different numbers of GPUs that run at different non-overlapping times of the month. Compute Engine breaks down the number of GPUs used across all VMs and combines them to qualify for the biggest sustained usage discounts possible.

If you run one VM with 1 GPU for the first half of the month, and then run another VM with 4 GPUs for the second half of the month, Compute Engine calculates discounts for these GPUs as if you had used 1 GPU for a whole month and 3 remaining GPUs for half of the month. Compute Engine applies the following sustained use discounts:

  • A 30% discount off the cost of using 1 GPU for a full month
  • A 10% discount off the cost of using the remaining 3 GPUs because you used each resource for half of the month

Viewing sustained use discounts

Sustained use discounts automatically appear on your bill at the end of the billing cycle. Sustained use discounts are a separate line item combining all discounts of all machine types for all projects in your billing account.

You can view the total sustained use discounts that you receive for each project and the cost of your VMs in the Google Cloud console billing history.

Sustained use discounts and Always Free usage quotas

Google Cloud offers Always Free usage quotas that provide free use of one e2-micro VM equivalent to the number of total hours within the current month. This is enough to run one VM without interruption for the entire month. You cannot receive sustained use discounts for use of the free tier VM.

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