# American -> implied probability, decimal -150 -> 150/250 = 60.0% decimal 1.667 -110 -> 110/210 = 52.4% decimal 1.909 +100 -> 100/200 = 50.0% decimal 2.000 +130 -> 100/230 = 43.5% decimal 2.300
American odds are awkward arithmetically (the formula changes sign at even money), which is why most quantitative work converts to decimal or straight to implied probability first.
ParlayAPI returns American or decimal prices via the odds-format request parameter, matching the-odds-api's interface so existing clients work unchanged. See the docs for request syntax and response shapes.