Nat King Cole · Nat King Cole Collectors Series

Unforgettable

Unforgettable is in B flat major at 128.9 beats per minute.

Tempo

129 BPM · Allegromedian of 208 analyses · 108.5–128.9 across the middle eight tenths

Key: B♭ major2 flats · the key most of the analyses agreed on
Agreement: 90%share of analyses that agreed
Analyses: 208people who ran the extractor
One beat: 465.5milliseconds, 60,000 ÷ BPM
Tuning: 438Hz · -8 cents from A 440
Dynamics: 5.9dB the level wanders from its average
Loudness: 0.445Essentia's 0–1 scale, not dB
Danceability: 0.92Essentia's danceability, 0–3

Source: AcousticBrainz, dump of 2022-06-23 (CC0) · MusicBrainz core data, 2026-09-17 (CC0) · how each number is measured. Measured up to 23.06.2022 — AcousticBrainz stopped collecting in 2022, so nothing released after that date is here.

What the numbers say

208 independent analyses of this recording were submitted to AcousticBrainz. Most of them — 90% — put it in B flat major, a key signature of 2 flats. The tempo printed above is the median of the 208 readings; 74% of them land within 2% of it, and the middle eight tenths of them run from 108.5 to 128.9 BPM.

At 128.9 BPM one beat lasts 465.5 milliseconds, so a sixteenth note is 116.4 ms and a dotted eighth 349.1 ms — the delay times for this recording. Counted half as fast it is 64.5 BPM, counted twice as fast 257.8. A score would mark that Allegro, by the ranges this site uses.

The analyses put the reference pitch of the recording at 438 Hz, which is 8 cents below concert A at 440 Hz — the sort of drift a tape machine or a slightly different mastering leaves behind. That is a fact about this transfer of the music, not about how it was played.

The dynamic complexity of the recording measures 5.9 dB: that is how far the level wanders from its own average, so a small number means a loud, flat master and a large one means a recording that still breathes. Its average loudness is 0.445 on Essentia's 0-to-1 scale, which is not decibels and is not comparable to a streaming service's number.

10 other recordings here are in B flat major; the ones listed below are the closest in tempo.

Beats per bar are not in this dataset. AcousticBrainz's analysis reports a tempo, a key and a loudness, and no time signature at all, so this page does not print one — a 4/4 here would be a guess dressed as a measurement.

Keys that fit with B♭ major

Each of these differs from B♭ major by at most one accidental, or shares its tonic. That is the whole of what a mixing wheel encodes; here the relations are named instead of numbered.

Delay times at 129 BPM

Note value	Beats	Milliseconds	Hertz
Whole note	4	1861.9	0.54
Half note	2	931	1.07
Dotted quarter	1.5	698.2	1.43
Quarter note (one beat)	1	465.5	2.15
Quarter triplet	0.667	310.3	3.22
Dotted eighth	0.75	349.1	2.86
Eighth note	0.5	232.7	4.3
Eighth triplet	0.333	155.2	6.45
Dotted sixteenth	0.375	174.6	5.73
Sixteenth note	0.25	116.4	8.59
Sixteenth triplet	0.167	77.6	12.89
Thirty-second note	0.125	58.2	17.19

Half time 64.5 BPM · double time 257.8 BPM. Every row is one beat (465.5 ms) times the fraction in the second column.

Closest in key and tempo

Recordings in B flat major, ordered by how near their tempo is to 129 BPM. A calculation, not a recommendation.

All songs in B flat major All songs at 129 BPM B♭ major at 120–129 BPM Nat King Cole

MusicBrainz collapses 209 recording ids into this one. Recording id 55a61b78-0621-466c-b09f-4cd60a659068.