Calculating Amazon EventBridge PutEvents event entry size - Amazon EventBridge
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Calculating Amazon EventBridge PutEvents event entry size

You can send custom events to EventBridge by using the PutEvents action. You can batch multiple event entries into one request for efficiency. The total entry size must be less than 256KB. You can calculate the entry size before you send the events.


The size limit is imposed on the entry. Even if the entry is less than the size limit, the event in EventBridge is always larger than the entry size due to the necessary characters and keys of the JSON representation of the event. For more information, see Amazon EventBridge events.

EventBridge calculates the PutEventsRequestEntry size as follows:

  • If specified, the Time parameter is 14 bytes.

  • The Source and DetailType parameters are the number of bytes for their UTF-8 encoded forms.

  • If specified, the Detail parameter is the number of bytes for its UTF-8 encoded form.

  • If specified, each entry of the Resources parameter is the number of bytes for its UTF-8 encoded forms.

The following example Java code calculates the size of a given PutEventsRequestEntry object.

int getSize(PutEventsRequestEntry entry) { int size = 0; if (entry.getTime() != null) { size += 14; } size += entry.getSource().getBytes(StandardCharsets.UTF_8).length; size += entry.getDetailType().getBytes(StandardCharsets.UTF_8).length; if (entry.getDetail() != null) { size += entry.getDetail().getBytes(StandardCharsets.UTF_8).length; } if (entry.getResources() != null) { for (String resource : entry.getResources()) { if (resource != null) { size += resource.getBytes(StandardCharsets.UTF_8).length; } } } return size; }

If the entry size is larger than 256KB, we recommend uploading the event to an Amazon S3 bucket and including the Object URL in the PutEvents entry.