Azure VM SKU

Question

Azure VM SKU

Handian Sudianto 7,571

In reservation when i want to purchase Standard E16-4as_v4 the portal showing this SKU have 16 vCPU

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But why when i try to change the SKU from VM then E16-4as v4 only have 4 vCPUs and not 16? User's image

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Answer accepted by question author

TP 164.6K Volunteer Moderator

Hi,

That is normal since E16-4as_v4 is constrained size. For purchasing/price purposes, you are paying for all 16 vCPUs when purchasing Standard_E16-4as_v4 reservation, which is same price as Standard_E16as_v4 (unconstrained size). You can see this yourself if you pretend to purchase Reservation and click on E16as_v4 and E16-4as_v4--the price is same.

Constrained sizes were created before they added the ability to customize number of vCPUs. The purpose [of constrained] is to have fewer number of vCPUs available inside of the VM (but full amount of RAM/IO) so that you could use fewer licenses for software that is licensed per CPU core (e.g. SQL Server).

-TP

Handian Sudianto 7,571 Reputation points

2026-10-12T23:22:33.3266667+00:00

hi @TP

This mean if i purcahse E16-4as_v4 then the reservation can be used if the vCPUs changed from 4 to 16?
TP 164.6K Reputation points Volunteer Moderator

2026-10-13T00:02:07.0133333+00:00
When you purchase Standard_E16as_v4 or Standard_E16-4as_v4 or Standard_E16-8as_v4, you are paying for full 16 vCPUs, and the price is the same. These are all part of Easv4 Series instance flexibility group, so can be used interchangeably in terms of discount being applied to VM.

For example, say you purchased Standard_E16as_v4 Reserved Instance. You could use for one VM running:

E16as_v4 (all 16 vCPUs enabled)

E16-4as_v4 (only 4 vCPUs enabled due to constrained)

E16-8as_v4 (only 8 vCPUs enabled due to constrained)

E16as_v4 (only 6 vCPUs enabled using Customize)

numerous other combinations

So to answer your question, yes, could switch from E16-4as_v4 VM (4 vCPUs) to E16as_v4 (16 vCPUs) if you want, and use same Reserved Instance. And reverse is true--as I said above if you purchase E16as_v4 Reserved Instance you could use it for VM running E16as_v4 or you could use it for E16as-4_v4 VM.
Handian Sudianto 7,571 Reputation points

2026-10-13T00:28:54.84+00:00

hi @TP

Thanks, now it's more clear for me. Let i try in the production by purchase the reservation.

1 additional answer

Your answer

Handian Sudianto 7,571 Reputation points

2026-10-12T23:22:33.3266667+00:00

hi @TP

This mean if i purcahse E16-4as_v4 then the reservation can be used if the vCPUs changed from 4 to 16?
TP 164.6K Reputation points Volunteer Moderator

2026-10-13T00:02:07.0133333+00:00

When you purchase Standard_E16as_v4 or Standard_E16-4as_v4 or Standard_E16-8as_v4, you are paying for full 16 vCPUs, and the price is the same. These are all part of Easv4 Series instance flexibility group, so can be used interchangeably in terms of discount being applied to VM.

For example, say you purchased Standard_E16as_v4 Reserved Instance. You could use for one VM running:

E16as_v4 (all 16 vCPUs enabled)

E16-4as_v4 (only 4 vCPUs enabled due to constrained)

E16-8as_v4 (only 8 vCPUs enabled due to constrained)

E16as_v4 (only 6 vCPUs enabled using Customize)

numerous other combinations

So to answer your question, yes, could switch from E16-4as_v4 VM (4 vCPUs) to E16as_v4 (16 vCPUs) if you want, and use same Reserved Instance. And reverse is true--as I said above if you purchase E16as_v4 Reserved Instance you could use it for VM running E16as_v4 or you could use it for E16as-4_v4 VM.
Handian Sudianto 7,571 Reputation points

2026-10-13T00:28:54.84+00:00

hi @TP

Thanks, now it's more clear for me. Let i try in the production by purchase the reservation.

Answer 1

Standard_E16-4as_v4 is a constrained vCPU size.

That is why the reservation purchase view can show the base size E16as_v4 as 16 vCPUs / 128 GB, while the VM resize view shows E16-4as_v4 with only 4 active vCPUs.

The mapping is:

Standard_E16as_v4 = 16 vCPUs, 128 GB
Standard_E16-4as_v4 = 4 active vCPUs, base size E16as_v4

Azure documents Standard_E16-4as_v4 in the constrained vCPU list with:

Active vCPUs: 4
Base size: E16as_v4

So the behavior shown in the portal is expected:

Reservation page is reflecting the underlying/base VM family size information.
VM size change page is reflecting the actual constrained SKU with 4 active vCPUs.

If the requirement is 16 usable vCPUs, select Standard_E16as_v4, not Standard_E16-4as_v4.