How to use the email send time response comparison
Advice like "10 AM is the best time to send" falls apart across industries, countries and list types, so this tool does not name a best hour. Instead you enter the sends and responses from your own send-time slots and compare the response rates side by side.
Each row divides that slot's responses by its sends. The overall figure is total responses รท total sends, not the average of the row rates, which is why the formula appears in the label โ the two diverge as soon as the slots have different send volumes.
For the comparison to mean anything, hold everything except the hour steady: the same segment, comparable subject lines, the same day of week. A slot with very few sends will swing wildly on chance alone. If the best-to-worst gap is small, subject lines and targeting are probably driving your response rate far more than the send hour is.
Frequently asked questions
Published send-time benchmarks disagree sharply depending on who ran the study, the industry and the country, so there is no defensible basis for naming one hour as optimal. Comparing measured results from your own list is far more reliable.
Pick one definition โ replies, clicks or reaching a goal page โ and apply it to all four slots. Using a different definition per slot makes the rate comparison invalid.