This disclosure describes systems, methods, and devices related to tone mapping for a high-efficiency (HE) trigger-based (TB) null data packet (NDP) feedback physical layer protocol data unit (PPDU). A device may identify a frame received from a second device. The device may determine, based on the frame, a resource unit allocated to the device, wherein the resource unit is associated with a 20 MHz sub-channel of a bandwidth. The device may determine, based on the resource unit and the bandwidth, tones associated with a HE short training field (HE-STF) of a HE TB NDP feedback PPDU. The device may send the HE TB NDP feedback PPDU to the second device in the 20 MHz sub-channel, wherein the HE TB NDP feedback PPDU includes the tones.