Apportionment Calculator

Apportionment Calculator hands out a fixed number of seats among states in proportion to their populations — the problem the U.S. House has faced since 1790 — and shows you exactly how each method gets there.

SEVEN METHODS • Hamilton's method • Jefferson's method • Lowndes' method • Webster's method • Adams' method • The Huntington-Hill method • The method of equal proportions

HOW IT WORKS Type in the seats and each state's population, or import a table from a CSV or Excel file. Calculate, and you get the standard divisor, each state's quota, the initial seats and the final apportionment, laid out in a table you can read across.

COMPARE Put all seven methods side by side and see where they disagree — the seats that move from one state to another depending on which method is used.

LEARN Every calculation comes with the steps that produced it: the divisor, the quotas, the rounding rule, and the adjustment that lands on the right total. Each method also carries a short history — who devised it, when it was used, and why it was replaced.

EXACT ARITHMETIC Divisors and quotas are worked out in exact fractions rather than floating point, so the numbers never drift. The 2020 census apportionment comes out right to the seat.

ALSO • Your last 50 calculations saved, with starred ones kept for good • Export a calculation as CSV, or share it as text • Four color themes, light or dark • iPhone, iPad and Mac, each with a layout built for it

FREE AND PAID Hamilton's, Jefferson's and Lowndes' methods are free to use — no ads, no account, no sign-up. Webster's method, Adams' method, Huntington-Hill and equal proportions can each be unlocked on their own, or all together with Pro. One-time purchases, not subscriptions.

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