In the Sōtō Zen tradition, the posture of shikantaza is treated as an expression of the practice itself, where body, breath, and mind quietly align. One sits on a firm cushion (zafu), usually placed on a mat (zabuton), with the hips slightly higher than the knees so the pelvis can tilt gently forward. A stable base is essential: full lotus, half lotus, or Burmese position are commonly used, and seiza or an upright chair posture with feet flat on the floor are also acceptable when needed. In every case, both knees should rest firmly on the mat or floor, creating a grounded tripod with the base of the spine. Sitting near the front of the cushion allows a subtle forward tilt from the hips without collapsing the torso. This physical stability supports an attitude of quiet alertness rather than strain.

From this base, the spine is kept upright and naturally extended, neither rigid nor slumped, with the chest open but not thrust forward. The pelvis tilts slightly forward to support the natural curve of the lower back, and the lower abdomen is gently engaged, as if the center of gravity rests in the hara below the navel. The neck follows the line of the spine, with the chin slightly tucked and the crown of the head subtly lengthening upward, which helps elongate the back of the neck. Shoulders are relaxed and level, allowed to drop without collapsing the chest, and the elbows hang slightly away from the body so that the arms can curve naturally. This balanced alignment embodies a posture that is at once dignified and unforced.

The hands rest in the cosmic mudra (hokkai jōin), which quietly gathers attention at the center of the body. The left hand is placed palm up in the right hand (or, in some lineages, the reverse), with the thumbs lightly touching to form a horizontal oval. This mudra is held against the lower abdomen, just below the navel, with the forearms relaxed and the hands close to the body. The mouth remains gently closed, the tongue resting lightly against the roof of the mouth just behind the upper teeth, and the jaw relaxed. Breathing is through the nose, allowed to be natural and unforced, without deliberate regulation or counting, so that posture and breath gradually settle into mutual support.

The eyes are kept open or half-open, with the gaze lowered at roughly a forty-five-degree angle toward the floor or wall a short distance ahead, without fixing on any particular object. Vision is soft and unfocused, allowing phenomena to appear and pass without interference. Some practitioners gently rock the body side to side and front to back at the beginning, coming to rest at the point of greatest ease and stability. In this way, the posture becomes a silent teaching: upright yet relaxed, stable yet ungrasping, sitting as “just sitting,” with nothing extra added and nothing left out.