[Microsoft 365] How many devices can be used? Installation and sign-in limit is


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Microsoft 365 is a contract form that allows you to use Office apps and Microsoft services on a subscription basis.
Office can be installed on multiple devices, so it’s a great service for people who use different devices.

However, there are conditions on the type and number of devices that can be installed and used with Microsoft 365, and if you use it without understanding it well, it may cause functional restrictions or license violations .

If you want to use Microsoft 365 on multiple devices, be sure to understand the conditions for installation and sign-in.

The difference between the number of installations and the number of signed-ins

First of all, let’s check the difference between ” installed number ” and ” signed-in number ” , which is important when considering the number of devices that can be used with Microsoft 365 .

  • Install: Putting an app/software on a device and making it available
  • Sign in: Authenticate and confirm you are the owner of the license

“Installation” means putting software into a computer or smartphone.

However, Microsoft 365 Office apps cannot be used just by installing them .

Only after confirming that the user is a licensed owner of Microsoft 365 does the right to use Office apps arise.

For this reason, when you launch an Office app for the first time, you will first be asked to authenticate your account.

Entering your email address and password here and authenticating is “signing in” .

With Microsoft 365, the number of devices that can be installed and the number of devices that can be signed in to are different , so each must be within the limits.

The number of devices that can be installed and signed in for each plan and the detailed conditions are explained in the next chapter.

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Usage by Microsoft 365 plan

In Microsoft 365, different conditions are set for home plans and business plans regarding the number of units used.

Make sure you understand the maximum number of devices that you can use with your plan.

Personal/Family plan

Microsoft 365 home plans have unlimited app installations .

You can also install it on all your devices.

However, the maximum number of devices that can be signed in at the same time is 5 .

Any combination of PC, tablet and smartphone is acceptable.

Business/Enterprise plans

The number of units used for corporate plans is

  • Up to 5 PCs
  • up to 5 tablets
  • Up to 5 smartphones

Up to 15 units can be installed.

Please note that in the case of corporate plans, it is limited to 5 devices for each type of device , so it is not possible to install on 15 computers.

Note that hybrid Windows devices (such as Microsoft Surface Pro) can be counted as either PCs or tablets.

Points to note when installing Microsoft 365 on multiple devices

Here are some points to keep in mind when using Microsoft 365 on multiple devices.

Cannot create or edit after signing out of Office application

In the case of a home license, you can only sign in to a total of 5 devices at the same time, so if you use Office on multiple devices, you may be signed out from unused devices so as not to exceed the upper limit.

Even if you sign out, the Office apps will not be uninstalled, so you can start the apps left on the device, but you will be in a “restricted function mode” where you cannot create or edit new ones .

If you want to use it again, you need to sign in again .

Automatic license activation does not occur if the device is offline

Microsoft 365 automatically activates the license periodically, but if the device is offline, automatic activation may not occur and functionality may be restricted .

When you connect to the network again, authentication will be performed and all functions will be available again.

Watch out for license violations

One Microsoft 365 license is required per person (excluding the Family plan).

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If 5 people use 1 shared computer, is 1 license sufficient? It is easy to misunderstand, but licenses must be purchased for the number of people .

For the same reason, it is also prohibited to install one license on five different computers of different users .


We have summarized frequently asked questions and answers about Microsoft 365 installation/sign-in number and license activation.

What happens if I sign in beyond the limit?

If you try to sign in again after exceeding the maximum number of signed-in devices, you will be signed out from the signed-in devices .

For example, the Microsoft 365 home plan has a limit of 5 simultaneous sign-ins, so when you try to sign in on the 6th device, you will be automatically signed out from the other device. I’m here.

Can I check the number of devices that are signed in?

In the corporate plan of Microsoft 365, the upper limit of the number of devices that can be signed in is 15 in total, and it may be difficult to know which terminal you are signed in to.

You can check your signed-in devices on the account management screen .

What if “Unlicensed product” is displayed?

If “Unlicensed product” is displayed when you start Office, the activation has failed for some reason and the product is in reduced functionality mode.

Please try the following to resolve it:

  • connect to network
  • Click the “License Authorization” button to authorize
  • sign in again
  • Repair Office
  • Reinstall Office

Office Repair Instructions

  1. Open “Programs and Features” from the “Control Panel”.
  2. Select Office and click Change.
  3. Select “Quick Repair” and click “Repair”.
  4. If the quick repair does not solve the problem, perform an “online repair” while connected to the Internet.

Office reinstallation procedure

  1. Open “Programs and Features” from the “Control Panel”.
  2. Select Office and click Uninstall.
  3. After uninstalling, restart your computer and install Office.

A computer licensed by a retired person. Can I use Office as is?

It is NG to use the licensed Office as it is on the computer that the retired person used, because it corresponds to the reuse of another person’s license .

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Sign out and then sign back in with your account.

Article Summary

I explained the number of users who can install and sign in to Office on Microsoft 365 and detailed conditions.

  • Microsoft 365 licenses are required for the number of users (excluding Family plan)
  • Unlimited number of installations for home (Personal / Family) plan, up to 5 simultaneous sign-ins
  • Corporate (Business / Enterprise) plans can be installed and signed in on up to 5 PCs, tablets, and smartphones.
  • Using a license for multiple people is a violation of the license.
  • If the automatic license authentication fails, it will enter a “restricted function mode” in which you cannot create or edit new files.

Multi-device support is a major strength of Microsoft 365 as a subscription.

Install Microsoft 365 on the device you use most often, and use it according to the situation, such as Windows at home , Mac when you’re out and about , and iPad when you’re on the move .