Objective: This study aimed to evaluate the training and implementation of the gravimetric method for estimating postpartum blood loss in clinical practice in Indonesian midwife-led birth centres. Background: Postpartum haemorrhage remains a leading cause of maternal death, particularly in low-resource settings. There is no gold standard for assessing blood loss volume during labour and childbirth. Studies recommended using a gravimetric method to measure blood loss in low-resource settings due to its relative accuracy and simplicity. Study design and methods: An online training module for the use of the gravimetric method was developed. All participants undertook the training and were asked to implement the method in clinical practice. A pre/post-test study design was used to examine midwives’ understanding of the gravimetric method; their implementation experience was explored using a structured questionnaire. Knowledge was assessed pre-training. The training consisted of both theoretical and practical elements and the opportunity for participants to ask questions. Post-training tests were administered, followed by a one-month period of implementation and an evaluation of their experience of using the method in practice. Results: Two hundred and eighty-five midwives from 17 health facilities were recruited to the study, and a total of 101 midwives from 12 health facilities completed all elements. The participants’ understanding of the gravimetric method improved significantly following the training. Although a number of challenges were identified regarding the implementation of the gravimetric method in practice, the participants were generally positive about its use, and 89% said that they would recommend this method to colleagues. Conclusion: A three-hour online training effectively improved participants’ understanding of the gravimetric method for assessing blood loss volume. This study identified midwives’ positive experiences with the gravimetric method and identified areas to improve practitioner experience of implementation in practice. Implications for research, policy, and practice: A three-hour online training followed by a one-month implementation period could be an effective and efficient approach to developing midwives’ understanding and use of the gravimetric method of blood loss estimation postpartum. What is already known about the topic? • The gravimetric method estimates the blood loss volume by weighing sanitary materials used during the labour process (i.e., gauze, sheets, swabs, pads, etc.) before and after being contaminated by the blood. • In clinical practice, the weight difference (in grams) is considered as ‘blood loss volume’ for ease of measurement and reported in millilitres without any formal conversion of units of weight to volume. • The benefits of the gravimetric method have been reported previously. However, there is limited evidence on the evaluation of this method to train midwives regarding implementation of the gravimetric method in clinical practice. What this paper adds • An online training programme is effective in increasing midwives’ knowledge and awareness of the gravimetric method for postpartum blood loss assessment. • The midwives found the gravimetric method simple to adopt in clinical practice, which increased their confidence in detecting postpartum haemorrhage. • The midwives encountered some barriers while implementing the gravimetric method and provided strategies to mitigate the issues raised.