files/en-us/web/api/progressevent/total/index.md
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The ProgressEvent.total read-only property is a number indicating the total size of the data being transmitted or processed.
For ProgressEvents dispatched by the browser, the value refers to the size, in bytes, of a resource and is derived from the Content-Length response header.
In a ProgressEvent you create yourself, this may also be the total bytes of a resource, although this can be any number.
For example, you may wish to normalize total to a value such as 100 or 1 if revealing the precise amount of bytes of a resource is a concern.
If using 1 as a total, then {{domxref("ProgressEvent.loaded")}} would be a decimal value between 0 and 1.
If the event's {{domxref("ProgressEvent.lengthComputable", "lengthComputable")}} property is false, this value is meaningless and should be ignored.
A number.
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