Smart Send Time provides insight into your customers' engagement by using data to find the optimal messaging time to maximize open and click rates. To choose the best send time, Smart Send Time looks at how engagement changes over a 24-hour time period for several email sends. In Klaviyo, you can see how and why a send time was chosen.
In this article, you will learn about the different stages of Smart Send Time and where to go to view the results.
About Smart Send Time
Klaviyo uses a two-part process to pick the optimal send time.
The first is the exploratory send. Over a 24-hour period, Klaviyo sends out an email, and each recipient is randomly assigned a time in their local time zone. If someone is assigned to receive an email at 11 a.m., they will get it at 11 a.m. in their local time.
Your number of campaign recipients affects how many exploratory sends are required. Keep in mind that Smart Send Time is only available for accounts with at least 12,000 active profiles and for campaigns with at least 12,000 recipients. If you have fewer profiles, the sample size is too low for Klaviyo to accurately determine the best send time, so it’s important to grow your list first.
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After the exploratory send(s), Klaviyo will determine the best time for the highest engagement and will perform a focused send. In this stage, one email will send at a given time, one will have sent two hours prior, and one will send two hours after in order to validate the selected time.
Understand Smart Send Time Data
Navigate to the Campaigns tab. Next, click Options and View Smart Send Time Report.
Here, you will be able to view data from your Smart Send Time campaigns. You can view your Smart Send Time Activity, which shows when you sent an exploratory or focused campaign, if the focused time has changed, and more. In addition, there are graphs that show the open rate per hour, opens and conversions per hour, and expected open rate lift. Note that the open rates represented in these graphs are only inclusive of campaigns sent using Smart Send Time.
In the sections below, we go over each of these graphs.
9/20/21 Update: with the release of iOS 15, macOS Monterey, iPadOS 15, and WatchOS 8, Apple will change the way that we receive open rate data on your emails by prefetching our tracking pixel. With this change, it’s important to understand that open rates will be inflated.
With regard to Smart Send Time, Klaviyo does not look at open data on the individual level, so the optimization should still function as anticipated. However, it may take longer to converge to an optimal send time.
For complete information on ways to potentially mitigate these Apple open changes, visit our iOS 15: How to Prepare for Apple’s Changes guide.
Open Rate per Hour
The Open Rate per Hour graph shows you the percentage of people who opened a Smart Send Time campaign out of those who received your email at a certain time. Exploratory sends, for example, send a campaign to different recipients over a 24-hour period. This graph shows the percentage of people who opened the email for each hour. For instance, 1 p.m. data shows the percentage of people who opened the email who received it at 1 p.m. in their local timezone. If a focus send has a much higher open rate than any of your other sends, we only analyze the relative change between hours which is reflected in this graph. This means that if a single campaign does very well, we will not spike the hours for that focus send because a single campaign performed better than average.
This graph only applies to campaigns using Smart Send Time. It does not include your historical campaigns or ones sent without Smart Send Time, as differences in subject lines and other factors could skew the results. Due to this, the rates may look different than your typical open rates.
Opens and Conversions per Hour
The Opens and Conversions per Hour graph shows the number of opens and conversions (e.g., Placed Order events). As with the Open Rate per Hour graph, all times are based on when the email was sent. If someone received the email at 8 a.m. but didn’t place an order until 9 a.m., the placed order event will still be attributed to the 8 o’clock email.
The opens and conversions are only taken from your Exploratory Sends and are not based on any campaigns sent previously so that they will accurately compare different sending hours.
Expected Open Rate Lift
The Expected Open Rate Lift graph compares your open rate with and without Smart Send Time, showing how much it is expected to increase when you send at the optimal time. For this graph to display, at least 1 of the last 10 campaigns must have been sent to 5,000 or more recipients.
Since many factors (like subject lines) affect open rate, Klaviyo normalizes this calculation using a combination of your previous sending times and your exploratory sends to get a weighted average. This is compared with the open rate at your initial optimal time to calculate lift.
When to Expect to See Results
The graphs will not be available when you first get started with Smart Send Time, as they depend on the information gathered by exploratory and focused sends. If you have never sent an exploratory campaign, all the graphs will be empty. This will remain true while your initial exploratory campaign is sending or if there is not enough data from an exploratory campaign, so as to avoid showing misleading results. This may take more than one exploratory campaign.
Once a campaign gathers enough data and there are attributed recipients, you’ll begin to see how your subscribers engage with the email over the 24-hour period. Data will include the open rate per hour (in the recipient’s local timezone) as well as opens and conversions (e.g., placed order) per hour. The Expected Open Rate Lift graph, which shows how your open rates compare before and after using Smart Send Time, will not populate until a focused send time has been reached.
It typically takes multiple exploratory campaigns to gather enough information to find a focused send time. Once Klaviyo gathers enough data and determines a focused send time, it is not possible to send another exploratory send. At this point, you will see a summary about the previous exploratory campaigns, the time chosen for the focused send, and the Expected Open Rate Lift graph.
After a focused send, the Smart Send Time may change if the data indicates engagement is higher at a different time. This may happen at any point when using Smart Send Time since your subscriber list may grow and their preferences may change over time. It is a best practice to send a focused campaign on a regular basis (e.g., once every six months or year) to ensure that this time is still best for your audience.
See Why the Optimal Smart Send Time Changed
Every time Klaviyo analyzes a campaign, we give a brief description of the conclusions we drew from that campaign in the activity timeline and state if the time changed because of it. Using the filter on this activity timeline, you can also select to only see Data Analyzed events, which will show all the results from all of your campaigns.