Blood transfusion service is a health service utilizing human blood as a basic material for humanitarian purposes and not for commercial purposes. So, blood transfusion health services include planning and preservation of blood donors, blood providers, blood distribution, and medical actions for giving blood to patients for the purpose of curing disease and restoring health. The blood distribution to hospitals by the PMI Blood Donor Unit is a pick-up system if carried out in the vicinity of the PMI concerned. Therefore, the request for blood by the recipient to the hospital or the PMI Blood Donor Unit takes before the hospital makes a blood request to the PMI Blood Donor Unit. The hospital blood bank makes an offer to the patient or the patient's family in need for blood. whereas the hospital blood bank is a service unit in the hospital responsible for the availability of blood for safe, good quality, and sufficient transfusion in supporting health services in hospitals and other health care facilities. One way to reduce the risk of a shortage and excess of blood needs is by applying an estimation algorithm to determine future blood needs and supplies. The objective of this paper is to apply an estimation algorithm to estimate the supply of Fresh Frozen Plasma (FFP) at PMI Gresik, whereas FFP is a yellowish blood component. FFP is a blood product processed from whole blood. This paper used a reliable estimation method, that is, the Ensemble Kalman Filter method and the Extended Kalman Filter method. The simulation results show that both methods had good accuracy, but the EnKF method was more accurate with an error of about 4%.