Systems, methods, and apparatuses for generating variable length block acknowledgement fields in a wireless network are provided. One aspect of this disclosure provides a method of wireless communication. The method includes receiving, by an apparatus, an indication of block acknowledgment (BA) parameters, and determining, by the apparatus, a size of a bitmap field based on the BA parameters. The method further includes generating, by the apparatus, a block acknowledgment (BA) frame comprising the bitmap field and an indication of the determined size of the bitmap field.