Why does A4 equal 440 Hz?

The story behind the universal tuning standard and why orchestras worldwide tune to A440.

The International Tuning Standard

In 1939, an international conference established A4 = 440 Hz as the standard concert pitch. But it wasn't always this way.

Historical Variations

Throughout history, concert pitch has varied wildly:

Era Typical A4 Frequency
Baroque (1700s) 415 Hz
Classical (1800s) 430-435 Hz
Modern 440 Hz
Some orchestras today 442-445 Hz

Why 440?

The choice of 440 Hz was somewhat arbitrary. It was a compromise between:

  1. European orchestras (which preferred higher pitches for "brilliance")
  2. American manufacturers (who wanted standardization)
  3. Singer preferences (who found lower pitches easier)

The Debate Continues

Some musicians advocate for A432, claiming it sounds more natural and resonates with the universe. While scientifically unproven, it remains a popular alternative in some circles.