OBJECTIVE: This study aims to compare two oscillometric devices used in national health surveys in Germany, Datascope Accutorr Plus and Mobil-O-Graph PWA and to develop formulas for the conversion of blood pressure (BP) values. METHODS: One hundred and four adults aged 21–86 years had nine alternate same-arm BP measurements according to the International Protocol revision 2010 for the validation of BP measuring devices in adults of the European Society of Hypertension. Measurements 2–8 yielded six pairs of measurements at 30- to 60-second interval with the two devices, totaling 743 pairs used for analysis. RESULTS: Mean Mobil-O-Graph SBP and DBP were higher than those from Datascope. Mean differences (Mobil-O-Graph minus Datascope) increased within BP ranges (optimal, normal, high normal, hypertensive stage 1, stage 2 and stage 3): SBP 0.5 ± 8.5, 3.1 ± 8.2, 3.7 ± 8.0, 5.3 ± 8.8, 13.8 ± 10.2 and 15.0 ± 25.9, respectively, and DBP 2.6 ± 5.6, 6.0 ± 4.9, 6.6 ± 5.2, 8.4 ± 4.8, 12.3 ± 4.6 and 20.4 ± 4.2, respectively. For Mobil-O-Graph pulse pressure less than 43 mm Hg, the DBP difference was 6.3 ± 5.5, and for Mobil-O-Graph pulse pressure more than 50 mm Hg, the SBP difference was 7.4 ± 9.3. The prevalence of BP at least 140/90 mm Hg was 28.8% with Mobil-O-Graph and 20.5% with Datascope. Bidirectional conversion models of SBP and DBP adjusting for BP, pulse pressure, sex, age and cuff width to arm circumference ratio were developed. CONCLUSION: The disagreement in oscillometric devices can reach a magnitude that can be relevant for clinical and epidemiological contexts. The here generated conversion formulas may help to improve comparability.