Monthly tracked users (MTUs) billing guide

Amplitude customers on Scholarship, Starter, and Plus plans bill according to monthly tracked user (MTU) count. This option is also available to customers on Growth and Enterprise plans. 

An MTU is a unique user who triggers one or more events within a calendar month. This can be either an anonymous user (which Amplitude tracks with device ID) or an identified user (tracked by user ID). If a user appears in two or more projects, they still count as a single MTU.

Amplitude tracks any anonymous users as distinct MTUs, even if they visited before while logged in. If an anonymous user subsequently logs into the site, all events triggered by the user while they were anonymous are merged under their user ID, and count as a single MTU.

Amplitude calculates MTU usage daily, with one more, final calculation after the end of the calendar month to accommodate any late-arriving events. At that point, the MTU count is no longer updated to reflect subsequent user merges caused by identify calls on anonymous users. 

Your MTU count doesn't increase due to user mapping, identify calls, or group identifies.

MTU-based pricing is available for all Amplitude plans. Customers who use sampling aren't eligible for MTU-based pricing.

Track your MTUs

The first step in setting up MTU tracking is to understand how Amplitude tracks unique users. The best way to ensure accurate counting of MTUs is to support a one-to-one correlation between user IDs and actual users.

Estimate your MTUs

If you haven't implemented tracking yet, you can use your monthly active user (MAU) count to estimate your current MTU usage. These counts should be similar, assuming they account for anonymous visitors identically.

View your MTU use

To view your MTU usage, navigate to Settings > Plans & Billing. MTU statistics are visible in their own panel.

Sometimes, a single user may count multiple times when totaling MTUs. This can happen when a user is logged in, but then later opens the app anonymously on a different device or platform. Because there is no way to connect these two users, they register as distinct MTUs unless the user eventually logs in on all devices. At that point, Amplitude merges their profiles into a single user.

It can also happen if a user has two unlinked user IDs and uses both of them in a single month.

There are also instances where a user’s actions can result in a reduced MTU count. If a user interacts with your app anonymously and then later logs into their account on that same device, the anonymous usage are merged with the logged-in usage, resulting in a single MTU.

See this post in the Amplitude Community to learn more about investigating your organization's MTU usage.

Discrepancies with counts provided by other tools

No two tools work exactly the same way, or under the exact same conditions. Most ingest and process data differently, which generate different results. Additionally, your MTU count could differ from the results generated by running a query of user count within Amplitude due to the way it calculates MTUs.

If you believe there is an error in your MTU count, contact Amplitude support.

MTU limits

MTU limits are defined by the plan your organization is on, or the MTU volume you purchased. Amplitude determines whether any you owe overage fees based on:

• Your total MTU volume, and
• Your events per MTU volume

These are each calculated on the last day of each calendar month. Exceeding either limit can result in overage charges. Amplitude alerts you when you are approaching your limit so you can take steps to avoid exceeding it.

Exceeding your plan’s allowed MTU volume

Exceeding your plan limits or purchased MTU limit results in charges for all excess MTUs recorded. 

For example, if you purchase n MTUs, and Amplitude records n+m MTUs at the end of the month, you're charged for m extra MTUs.

Exceeding your plan’s events per MTU limit

Regardless of the plan you’re on, you're' be subject to a cap on events per MTU. Amplitude calculates this cumulatively.

For example, if you purchased n MTUs and expect to have x events per user, when your event volume k exceeds n(x), you could see a charge for the difference based on the formula

(* - n(x)) / x = number of excess MTUs

Exceeding limits on a free plan

If you're a non-paying customer, Amplitude blocks your account when you exceed your MTU monthly limit three times. You lose access to your charts and dashboards (you keep have access to certain admin functions, like the User API, so you can meet your compliance obligations). Amplitude continues to ingest data up to and over your limit; however, unless you upgrade to a paid plan, you can't to access it. If you continue to exceed your monthly limit without upgrading to a paid plan, Amplitude deletes your account six months after it's' first blocked.

Unexpected usage spikes

Large and sudden increases in MTUs are almost always tied to spikes in usage of your product. If your company recently launched a new marketing campaign, a significant product update, or a change to your instrumentation, that may be the most likely explanation.

MTUs may also increase unexpectedly when you add new event sources that result in either more users, or more events for users active in third-party tools but not necessarily in your product (for example, adding an email platform as a data source).

If you believe your MTUs have spiked in error, contact Amplitude support.

How Amplitude counts backfilled events

When you add backdated events for previous months, Amplitude adds one MTU for each month in which a distinct user appears.

Amplitude bases MTU usage calculations on the month you add an event to Amplitude. If backfill data from previous months in February, for example, Amplitude counts all this backfilled usage against February’s MTU quota.

Similarly, determining whether a user is unique or not also hinges on the month they trigger the event. For example, if Amplitude records three events for a single user, with one dated today, a second dated one month ago, and a third dated two months ago, the count is one unique MTU, counted in this month.

Because of this, backfilling data is a common cause of spikes in MTU usage.

Drop filters and MTUs

When you use a drop filter, Amplitude excludes a set of ingested events from your chart, based on the criteria you set. These events aren't returned by your query, but they do still exist: Amplitude doesn't delete them. Because of this, the number of uniques you see on a drop-filtered chart in Amplitude Analytics may not match the number of uniques on the MTU chart in your billing report.