Methods, apparatuses, and computer readable media for signaling high-efficiency packet formats using a legacy portion of the preamble in wireless local-area networks are disclosed. A high-efficiency (HE) wireless local area network (HEW) device including circuitry is disclosed. The circuitry may be configured to generate a HE packet comprising a legacy signal field (L-SIG) followed by one or more HE signal fields, and configure the L-SIG to signal to a second HEW device either a first packet format of the HE packet or a second packet format of the HE packet, where a length of the L-SIG modulo 3 is used to signal the first packet format or the second packet format. The circuitry may be configured to generate a duplicated L-SIG field with a polarity difference to indicate a third packet configuration of the HE packet or a fourth packet configuration of the HE packet.