BACKGROUND: We investigated whether the use of a specially designed visual estimation tool may improve accuracy in quantifying blood volumes related to surface spreading. METHODS: A prospective, paired-control, single-blinded experimental study was performed at a medical university. Anesthesiologists and emergency medical personnel estimated various blood volumes on surfaces with varying absorptivity (carpet, towel, polyvinyl chloride, wooden flooring) in an experimental setting. We assessed the sensitivity of training blood volume quantification using a self-designed visual estimation tool by comparing the accuracy of visual blood volume estimations before and after practical training with the tool. RESULTS: A total of 352 estimations by 44 participants were evaluated. Accurate estimations improved significantly from pre-training to post-training (P<0.05). The sensitivity of blood volume quantification was 33.0% after training with the visual estimation tool. Estimations did not depend on age, profession, gender or years of the estimator’s professional experience. CONCLUSIONS: Training with a visual estimation tool by professional rescuers can improve the estimation accuracy of blood volumes spread on surfaces with varying absorptivity.