String instrument tuning

Question

I've always wondered: Why are string instruments tuned in intervals of perfect fifths?

Violin: G3, D4, A4, E5

Viola: C3, G3, D4, A4

Cello: C2, G2, D3, A3

Stringed Bass: E1, A1, D2, G2

Answer 1

String instruments are tuned in Perfect 4ths and 5ths because these intervals are stable and pleasant, or in theory terms, highly consonant. These intervals don’t feel an active need to resolve, which makes tuning a simple task. Perfect intervals are essentially “mathematical truths.”

This standard tuning for string instruments allows for easy transposition. Because the strings are tuned in fifths, identical finger placements across adjacent strings naturally yield perfect fifths, while simple diagonal shifts yield fourths, thirds, and sixths.

Fun facts:

A 4th inverts to a 5th, and vice versa!

Ratio for a perfect 5th is 3:2

Answer 2

This is a great question!

Classical string instruments are typically tuned in 5ths because of something called Sympathetic Resonation, or Overtones. Basically when you play these instruments, the strings not currently being played are tuned to the most common notes that will reverberate and make the overall tone of the instrument sound warm and rich. There is a longer and more scientific answer but that's the gist of it :)

Also the string bass is actually tuned to perfect 4ths! Bass guitars are also tuned exactly the same.