The alto flute is a lower voiced member of the flute family. Though not as common as the traditional C flute, it is admired for its hollow rich sound and great depth of tone at lower pitches. Converting music from a C flute to the alto flute requires knowledge of both instrument's characteristics in terms of natural tuning and ranges.
Write out the C flute's melody on staff paper.
Transpose the key signature for the alto flute line on a new piece of staff paper. The alto flute is naturally tuned to G, meaning that every note that it plays sounds a perfect fourth lower than it is written. In transposing the key signature, move the key up a perfect fourth. A piece written in the key of G major with one sharp would be written in C for the alto flute and have no sharps or flats.
Write out the music for the alto flute, transposing each note up a perfect fourth. Be aware of the range limitations for the alto flute. If there are many notes written in the ledger lines (above the staff), writing them up a fourth from that may be too high for the alto flute. If this is the case, you may want to consider moving some of the higher phrases down an octave (still remembering, of course, that the notes should be transposed).