...A Bloom filter can use much less storage than the original set, but it allows for some 'false positives': it may sometimes report that an element is in the set whereas it is not. When you construct, you need to know how many elements you have (the desired capacity), and what is the desired false positive rate you are willing to tolerate. A common false-positive rate is 1%. The lower the false-positive rate, the more memory you are going to require. Similarly, the higher the capacity, the more memory you will use. You may construct the Bloom filter capable of receiving 1 million elements with a false-positive rate of 1%.