Tables that have previously been given for determining an appropriate inventory level for a blood type with a mean daily use of three units or less and a lifespan of 21 days have been recomputed, allowing all blood to have an additional seven days of life. These show that the longer blood life will make it easier to choose the optimal inventory level and lead to great savings in the loss due to expiry; it will also have a small beneficial effect on the frequency with which the bank is unable to meet requirements.