AbstractAimsDiagnosis of heart failure with preserved ejection fraction (HFpEF) can be challenging. This study aimed to evaluate the potential of a webtool to enhance the scoring accuracy when applying the complex HFA‐PEFF and H₂FPEF algorithms, which are commonly used for diagnosing HFpEF.Methods and resultsWe developed an online tool, the HFpEF calculator, that enables the automatic calculation of current HFpEF algorithms. We assessed the accuracy of manual vs. automatic scoring, defined as the percentage of correct scores, in a cohort of cardiologists with varying clinical experience. Cardiologists scored eight online clinical cases using a triple cross‐over design (i.e. two manual–two automatic–two manual–two automatic). Data were analysed in study completers (n = 55, 29% heart failure specialists, 42% general cardiologists, and 29% cardiology residents). Manually calculated scores were correct in 50% (HFA‐PEFF: 50% [50–75]; H₂FPEF: 50% [38–50]). Correct scoring improved to 100% using the HFpEF calculator (HFA‐PEFF: 100% [88–100], P < 0.001; H₂FPEF: 100% [75–100], P < 0.001). Time spent on clinical cases was similar between scoring methods (±4 min). When corrections for faulty algorithm scores were displayed, cardiologists changed their diagnostic decision in up to 67% of cases. At least 67% of cardiologists preferred using the online tool for future cases in clinical practice.ConclusionsManual calculation of HFpEF diagnostic algorithms is often inaccurate. Using an automated webtool to calculate HFpEF algorithms significantly improved correct scoring. This new approach may impact the eventual diagnostic decision in up to two‐thirds of cases, supporting its routine use in clinical practice.