Understanding Smart Send Time results

You will learn

Learn about the different stages of Smart Send Time and where to go to view the results.

Smart Send Time provides insight into your customers' engagement by using data to find when they are most likely to open your emails. 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.

About Smart Send Time

Klaviyo uses a 2-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. If Klaviyo does not know a recipient’s time zone, it uses your account’s time zone.

Your number of campaign recipients affects how many exploratory sends are required. Exploratory and focused sends require at least 12,000 recipients, and your account needs at least 12,000 active email profiles to begin testing. 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.

After the exploratory send(s), Klaviyo determines an initial optimal send time. You can then schedule a focused send to validate and refine it. Recipients are split into 3 groups: 1 receives the email at the selected time, 1 receives it 2 hours before, and 1 receives it 2 hours after, in their local time zones.

Understand Smart Send Time data

1. Navigate to the Campaigns tab.
2. Open the three-dot Options menu in the page header.
3. Click Smart Send Time report.
4. Select the test you want to review from the Test name dropdown.

Here, you can view data from your Smart Send Time campaigns. Smart Send Time activity 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, open and conversion rates per hour, and expected open rate lift.

Note that the open rates represented in these graphs are only inclusive of campaigns sent as part of the Smart Send Time test selected in the dropdown menu at the top of the page.

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 focused 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 focused send because a single campaign performed better than average.

This graph only applies to campaigns sent using the Smart Send Time test selected under Test name. It does not include your historical campaigns, ones sent without Smart Send Time, or ones sent as part of another Smart Send Time test, 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.

Open and conversion rates per hour

The Open Rate and Placed Order Rate per Hour graph shows the open and conversion rates (e.g., the Placed Order rate) from your exploratory sends. 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.

Generally, higher open rates correlate with higher conversions. Use this graph to confirm this behavior for your own audience.

The open and conversion rates are only taken from your exploratory sends for the selected Smart Send Time test, 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 the estimated open rate for your previous sending times with the estimated open rate at your initial optimal time. To calculate this comparison, Klaviyo needs 10 email campaigns sent without Smart Send Time, each with at least 5,000 recipients. The graph also requires an initial optimal send time.

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. Klaviyo waits until the campaign’s final scheduled send time plus your account’s longest email attribution window before analyzing its results. The graphs can remain empty if there is not enough data from an exploratory campaign, so as to avoid showing misleading results. This may take more than 1 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 open and conversion rates (e.g., Placed Order rate) per hour. The Expected Open Rate Lift graph estimates how sending at the initial optimal time compares with your previous sending times. It will not populate until a focused send time has been reached and enough campaign history is available for the comparison.

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 within that test. At this point, you will see a summary about the previous exploratory campaigns and the time chosen for the focused send. If enough campaign history is available, you will also see 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 after subsequent focused sends, since your subscriber list may grow and their preferences may change over time. Campaigns sent using Optimal Time do not update your Smart Send Time. It is a best practice to send a focused campaign on a regular basis (e.g., once every 6 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 in the selected test, it gives a brief description of the conclusions in the activity timeline. Under Smart Send Time activity, select Data Analyzed to see analysis results, including campaigns that could not be used to update the send time. Select Smart Send Time Updated to see when the recommended time changed. Click See More to view older events.

Additional resources