Cello tuner

Cello strings: notes and Hz

Equal temperament. The cello's A is the A below middle C, an octave under the viola and the violin's A. The reference switch above moves every string.

How to tune a cello with this tuner

Tap Start tuning and allow the microphone, then tap A and bow the open A string, long and even. The needle shows how many cents the string sits above or below A3; once it stays within five cents for a moment, the A ticks. Then tap D, G and C in turn and do the same. If you bow a string that is still to tune and close to its own note, the tuner switches to it by itself after three readings. When all four have ticked, tap Start tuning and go round them once more: tuning one string changes the pressure on the bridge and the top a little, so the first strings usually move a cent or two while you tune the last. A first, because the A is what the piano or the oboe gives and what the other strings are measured from. Use the fine tuners for the last few cents and the pegs only for bigger moves. With the microphone off, a tap on a string plays its note; a phone speaker plays the C and the G an octave up, because it can't play them, and the needle still reads your string at its real pitch.

Put the phone on the music stand, within a metre of the f-holes, not on the floor by the endpin. The C string sits at 65 Hz, where a phone's microphone is weak, and it speaks slowly: bow it with steady weight a little nearer the bridge, and give the needle a second or two before you turn anything. If the needle jumps, lay the left-hand fingers lightly on the strings you aren't tuning so they don't ring along. Plucking works too, but a bowed note gives the tuner a longer, steadier sound to read.

Pegs or fine tuners

The fine tuners are the small screws on the tailpiece, for the last few cents. Turn one clockwise, screwing it in, to raise the pitch, and counterclockwise to lower it; a quarter turn is a few cents. Student cellos usually have one on every string; many older or professional cellos have one only on the A, sometimes the D as well. When a fine tuner reaches the end of its thread, turn it back to the middle and make the change with the peg. Don't leave one screwed all the way in: on some designs the lever underneath can touch and mark the top.

The pegs at the scroll make the big changes. Turn a little at a time and push the peg into the pegbox as you turn, so it holds. On a normally strung cello, turning the top of the peg toward the scroll raises the pitch. Come up to the note from below: if you overshoot, go down past it and come up again, and the peg seats against the string's pull instead of slipping back. The C and G pegs sit on one side of the pegbox, the D and A pegs on the other.

Tuning a cello by ear

• The A. From a piano, it is the A below middle C. An A440 tuning fork sounds an octave higher: touch the A string lightly at its halfway point and bow the harmonic, which is A4, against the fork.
• Fifths. Bow A and D together. In tune, the fifth rings calm; out of tune, it wobbles, and the wobble slows as you get closer. Then D with G, then G with C.
• Harmonics. Touch the D string a third of the way along from the nut and the A string halfway along: both harmonics sound A4. Bow them one after the other or together and turn the D until they match. The same pairing works for G against D and C against G.

Pure fifths or the needle: why the C reads 6 cents low

A fifth tuned until it stops beating is 701.96 cents wide, 1.96 cents wider than a piano's. Tune from the A by ear and the error adds up string by string: the D lands 2 cents below the needle's centre, the G 4 and the C 5.9, at 65.19 Hz instead of 65.41. So after a by-ear tuning the tuner shows the C about 6 cents low and won't tick. Neither is wrong. Alone or in a string quartet, many cellists keep the fifths pure. With a piano, tune them a hair narrow, close to the needle, so your open C doesn't clash with the piano's C.

A at 440, 442 or 443

As of 2026 many European orchestras tune to A = 442 or 443 (the Berlin Philharmonic 443), and many US orchestras to 440, some to 442 (the New York Philharmonic). The oboe gives A4; your A string is the A an octave below, and the tuner folds the octave. 442 is 7.9 cents above 440, and 443 another 3.9 above that: on the 442 switch, an orchestra at 443 reads about 4 cents high. Next to a piano, tune to the piano: tap A, play its A3 into the tuner and match your string to whatever the needle shows.

Why a cello won't stay in tune

• New strings stretch for a few days; synthetic and gut strings longer than steel. Tune often, and expect it.
• The seasons. Dry winter air shrinks the pegs and they slip; humid summer swells them and they stick. Peg compound helps both; a peg that still won't hold needs refitting at a luthier's.
• The bridge. Every time you tune up, the strings drag the top of the bridge toward the fingerboard. Look at it from the side now and then: the back face should stand at a right angle to the top. A bridge that leans far can warp or fall, and when it falls, the sound post inside may fall too. Ease it upright with both hands, or take it to a luthier.
• How often. Every time you unpack it, and again after travel or a change of weather; a cello left for weeks comes out flat. Kept at room temperature and roughly 40–50 % humidity (a case humidifier in heating season), the pegs and the top move least.
• Changing strings. Change one string at a time, so the bridge and the sound post stay under pressure.

Scordatura: a cello in another tuning

Bach's fifth suite tunes the A string down to G (C G D G). Tap G and bow the lowered string: the tuner folds octaves, so G3 reads against the G string's G2. Kodály's Sonata for solo cello, Op. 8, lowers the C and G a semitone, to B1 and F♯2; for notes the four strings don't hold, the pitch detector names any note with its cents.

Electronic, clip-on or chromatic cello tuner?

A clip-on tuner clamps to the bridge and reads its vibration, so a noisy rehearsal hall doesn't bother it; clip it on the side of the low strings. A chromatic tuner names any note it hears. This page asks for the four open strings one at a time and compares each with its own note, from the phone you already carry. Cellos come in sizes from the smallest children's cellos to 4/4, and every size is tuned C G D A. Next to it: the viola tuner, an octave up, and the double bass tuner.

The notes you tuned go into Brumm as a short melody over a beat.