Introduction Currently, there is a paucity of literature describing the risk factors for increased perioperative blood loss (PBL) during total knee arthroplasty (TKA) in haemophilia. Furthermore, no studies have analysed coagulation factor levels that affect PBL. Aim To identify the risk factors for increased PBL by incorporating coagulation factor levels following TKA in patients with haemophilic arthropathy. Methods A total of 92 TKA (78 haemophilia A and 14 haemophilia B) were performed for haemophilic arthropathy. PBL was calculated using the haemoglobin (Hb) balance method, and patients were categorised into two groups: group H (higher blood loss than the mean PBL, n = 36) and group L (lower blood loss than the mean PBL, n = 56). Body mass index (BMI), operation day Hb, haematocrit and coagulation factor level (VIII or IX) were analysed, including demographic and laboratory data. Results The mean PBL volume during TKA for haemophilic arthropathy of the knee was 542.3 ± 361.7 mL. Multivariate analysis revealed that lower haematocrit on the operation day (odds ratio [OR], .633; 95% confidence interval [CI], .511–.786; p < .001) and coagulation factor level (OR .970, CI .941–.999; p = .046) were independent risk factors for increased PBL. Receiver‐operating characteristic analysis identified these cutoff values for predicting increased PBL: operation day coagulation factor level 93.5% (sensitivity, 70.4%; specificity, 67.6%) and haematocrit level of 38.2% (sensitivity, 85.7%; specificity, 80.6%). Conclusions The PBL increased as haematocrit and coagulation factor levels decreased on the operation day. A coagulation factor level <93.5% or haematocrit level of <38.2% may be a significant risk factor for increasing PBL. Level of evidence Level IV, Case Series, Treatment Study