Background/Aims: Consensus guidelines for performance and analysis of high-resolution esophageal manometry (HREM) recommend use of equipment, population and posture specific normative values. To provide normative values for Chicago classification (CC) metrics in the physiological seated position for a 16-channel water perfused system (Dentsleeve HREM catheter, Advanced Manometry Systems, Melbourne, Australia) widely used in India and other countries with limited access to solid-state equipment. The results are compared with published CC metrics in supine position done using the same system and volunteers. Methods: HREM tracings of ten 5 mL water swallows in sitting posture were acquired in healthy volunteers and normative values for CC version 3.0 metrics calculated. Individual swallows were paired with previously reported supine swallows for postural variations (Wilcoxon sign rank test) and concordance of CC diagnoses (Pearson coefficient). Results: Analysis of 530 sitting posture water swallows (53 subjects) and comparison with their supine data revealed significantly higher integrated relaxation pressure (IRP; median 6.7 mmHg vs 6.1 mmHg) but lower distal latency (DL; mean 6.3 seconds vs 6.8 seconds) and distal contractile integral (DCI; mean 1224 mmHg∙sec∙cm vs 1456 mmHg∙sec∙cm). Sitting posture normal was defined as: IRP < 13.9, DL > 4.5, and DCI = 115-4500 (absent contractility: DCI < 30). CC diagnoses concordance using posture-specific cut-offs was moderate (k = 0.47). Conclusions This paper provides normative values for the Advanced Manometry Systems 16-channel water perfused system in the physiological seated position for CC metrics. Our findings of higher IRP and lower DCI in sitting posture than previously reported supine CC cut-offs, confirm the need to use posture-specific cut-offs for reporting HREM tracings.