How many amendments does the U.S. Constitution have?

How to get close to this number

Build it from two things you probably know: the Bill of Rights is ten, and amendments since then have been rare. A couple of centuries at a rate of roughly one every decade or so, with long gaps, adds up to a number in the twenties. Constitutional amendment counts are low everywhere by design, so an estimate in the hundreds is the wrong shape entirely.

The reason the number stays small is the ratification threshold. An amendment needs supermajorities in Congress and then approval by three quarters of the states, which in a politically divided country is close to unreachable. The rarity is the intended feature, and it is why so much constitutional change in practice happens through court interpretation rather than through amendment.

The final amendment in the explanation is the best illustration of how the process actually works: proposed in 1789, ratified in 1992. Amendments do not expire unless their text says so, so a proposal can sit dormant for two centuries and then be completed. That is a genuinely strange property of the system and it is the most interesting thing attached to this count.