Ask the Perf Guy: Sizing Exchange 2016 Deployments

Published 10-15-2015 06:30 AM 182K Views

Uh oh. You are probably thinking to yourself, here comes another one of those incredibly long blog posts about sizing. Thankfully, it’s not. If you want to fully understand the sizing process for Exchange 2016, you are certainly welcome to read the previous post that I did for Exchange 2013, as the overall process is effectively the same with one major caveat. Since we have eliminated the CAS role in Exchange 2016, you must follow the process for multi-role deployment sizing. Overall, the inputs to our sizing formulas stay the same from Exchange 2013 to Exchange 2016. This means that our IOPS requirements, memory requirements, and all of the other values provided in the Exchange 2013 sizing guidance should continue to be used for Exchange 2016. We are changing one set of inputs, however.

Processor requirements

We are slightly increasing the processor requirements for Exchange 2016 (compared to Exchange 2013) as this is a very new release, and we are still learning how it performs in production. This slight increase in CPU provides some additional headroom for unanticipated issues, and may be changed in the future as we learn more from our internal deployments as well as customer feedback. The same SPECint_rate2006 baseline value described in the Exchange 2013 guidance should continue to be used (33.75 per-core).

Messages sent or received per mailbox per day Mcycles per User, Active DB Copy or Standalone Mcycles per User, Passive DB Copy
50 2.99 0.70
100 5.97 1.40
150 8.96 2.10
200 11.94 2.80
250 14.93 3.50
300 17.91 4.20
350 20.90 4.90
400 23.88 5.60
450 26.87 6.30
500 29.85 7.00

These changes are reflected in v7.8 and later in the calculator.

System scalability

The previously released guidance on maximum recommended cores and maximum memory size for Exchange 2013 is generally applicable to Exchange 2016 in terms of background and general scalability issues, however we have increased the recommended maximum memory size for currently supported versions of Exchange 2016 to 192GB. We recommend not exceeding the following sizing characteristics for Exchange 2016 servers.

Recommended Maximum Processor Core Count


Recommended Maximum Memory

192 GB

Note: Version 9.1 and later of the Exchange Server Role Requirements Calculator aligns with this guidance.


If you are at all familiar with the process for sizing the last couple of Exchange releases, you will be very comfortable with Exchange 2016. As with any new release, you should plan to roll-out in stages and monitor the health and performance of the solution carefully. We do expect that our performance and scalability guidance for Exchange 2016 will evolve over the lifespan of the product so watch the Exchange team blog for future updates.

Jeff Mealiffe

Principal PM Manager Office 365 Customer Experience

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Jeff, thanks for sharing and the updated information regarding the calculator.
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Thanks Jeff,

It's been a great help to all of us who requires Exchange on premise as messaging solution for enterprise.

KUDOS to Jeff and Team!!!

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Phew! Finally we have it, the easy way.
New Contributor

I’m using the calculator to size Ex2016. I’ve a very high percentage of mailboxes belonging to leavers which need to remain in on-prem Exchange for a number of years (yes, I’ve looked at other options to deal with these but it is what it is ... don’t ask!!). Clearly these mailboxes don’t send/receive msgs anymore and they are very infrequently accessed. How do I factor these into the calculator to ensure I’ve the storage for them and to accommodate the required Exchange horsepower to perform maintenance on them (indexing, defrays etc.) but so these don’t unnecessarily push my server count/specs up?

Any pointers would be really appreciated. Thx.

Frequent Contributor

Just wondering, since the 2013 sizing post is now archived and unavailable, will there be a repost of that information for 2016/2019? 

Senior Member

Is there an option available in this sizing calculator for Exchange 2016 server that will only be installed as stand alone to manage mail attribute in dir sync environment. MS requires to keep one stand alone Exchange 2016 server even if you have 100% mailbox in EXO and all mail flow is through EOP. How do we size stand alone server to support mail attribute management.

Occasional Visitor

@Bhavesh Shah Would be interested if you found a solution for your question. Had a talk with a MS consultant and with partner tech support. We have a support statement from MS for use of Exchange Server 2016 server as management server only. This means Exchange Server is not included in mail routing and all mailboxes are hosted in Exchange Online. In my current setup hybrid wizard is not used. The sync of Exchange attributes with AD Connect is activated. Only use of Exchange Server is to manage the Exchange attributes in AD. 

At the moment I try to work with the Management role only. The system is configured with 4 cores and 8 GB RAM but it seems this can be reduced to 2 cores and 4 GB RAM. But I have not finished testing the setup without mailbox role.

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