Respiratory inductive plethysmography (RIP) can measure breathing patterns noninvasively. Calibration is required for rib cage and abdomen transducers utilizing breaths with different compartment contribution correlated with tidal volume measured by integrated pneumotachography (PNT). This study was performed to determine if RIP remains accurate during sleep states following calibration in the quietly awake state. We used our single position graphic calibration technique (SPG) to calculate gain factors in seven tracheostomized lambs. Validation of gain factors was accomplished by comparing tidal volume obtained simultaneously by RIP and PNT during quiet wakefulness (QW), quiet sleep (QS) and active sleep (AS). Results of the study showed that RIP was accurately calibrated during QW. Accuracy was decreased during QS and AS.