American IPA's conventional style range runs roughly 40-70 IBU, one of the widest bitterness ranges of any common style family — reflecting genuine variation within the category, from a balanced, malt-forward IPA at the low end to an aggressively bitter West Coast-style IPA at the top.
A real schedule, not just a range
A three-addition schedule — 20 g at 14% alpha for 60 minutes, 30 g at 12% alpha for 15 minutes, and 40 g at 12% alpha at flame-out (0 minutes), in a 19 L batch at 1.062 boil gravity — computes to 50.0 IBU by Tinseth and 69.8 IBU by Rager, a wider-than-usual gap between the two formulas because the flame-out addition contributes zero Tinseth IBU (no boil time, no isomerization) but a meaningful chunk of Rager IBU (Rager's utilization curve doesn't hit zero at zero minutes the way Tinseth's does). Run this schedule yourself — both formulas land the schedule mid-range for the style regardless of which one you trust more.
Why the range is so wide for this particular style
IPA covers more genuine sub-style variation in bitterness than almost any other beer family — a session or New England-style IPA commonly sits toward the bottom of the range (or below it, since hazy IPA specifically trades bitterness for a softer, juicier hop character), while a traditional West Coast IPA built to showcase assertive hop bitterness sits at or above the top. If you're targeting a specific IPA sub-style, check that sub-style's own guideline on the style reference rather than the broad "American IPA" family range — a hazy IPA built to the top of the 40-70 range would taste unbalanced for what that sub-style is actually going for.
Bitterness alone isn't the whole picture
A calculated IBU number doesn't automatically translate to a proportional perceived bitterness — that depends heavily on the beer's gravity, since a higher-gravity beer's malt sweetness balances out bitterness that would taste sharp in a lower-gravity one. See what is a good bitterness-to-gravity ratio for the BU:GU figure that accounts for this, rather than judging a recipe on IBU alone.
If your target and your actual result don't match
A schedule calculated to hit a specific IBU on paper can still miss in the glass for reasons the formula doesn't capture — actual alpha acid varying from the published range on your specific hops, or pellet vs. whole-cone form affecting utilization. If you're chasing a specific number for competition or consistency, the IBU calculator is the place to iterate on your schedule, and checking your hops' actual Certificate of Analysis against the range used in planning closes most of the remaining gap between a calculated target and a measured result.