The amount you get per stream depends on numerous factors and changes from artist to artist. This is because the royalty rate depends on the store that the stream comes from, where in the world the listener is from, the product the listener uses and in some cases, the length of the stream.
You'll be able to determine your average royalty rate after you get your first report from SpareMusic. This should give you a somewhat accurate estimate of the amount you get per stream and you should be able to estimate what you should get the next month.