For over 50 years, oral methadone was considered to be 3/2 the strength of morphine.That means that 20mg of
methadone is equivalent to 30mg of
morphine. (All opioid strengths are based on the so-called "gold standard" of analgesia, morphine sulfate.)
This means methadone is 150% the strength of morphine.
Recently, they've changed that ratio to a much more conservative number. At low doses of morphine equivalent, the ratio is 8/1 or 800%.