Song duration calculator

Non-positive tempo or a non-positive measure count is rejected with invalid_input so a script never treats a zero-BPM sketch as an infinitely long track.

How BPM, time signature, and measures become minutes and seconds

Time signature writes two numbers: the numerator, sent as beats_per_bar, says how many of those pulses fill one measure, and the denominator, sent as beat_unit, names the written note that receives the pulse — four for a quarter, eight for an eighth, two for a half, and one, sixteen, or thirty-two for the remaining legal note values.

How to call the API and what comes back

Send a JSON body with four required finite numbers. The field bpm is the tempo in beats per minute; aliases tempo, beats_per_minute, and tempo_bpm are accepted. The field measures is the bar count; aliases bars, measure_count, num_measures, and n_measures map to the same value, and a fractional count is legal for a pickup or a fade that does not land on a downbeat. The field beats_per_bar is the time-signature numerator (four in 4/4, three in 3/4, six in 6/8). The field beat_unit is a closed enum of written note values that may sit on the bottom of a meter: one, two, four, eight, sixteen, or thirty-two. Absolute values must stay within the published limit of one trillion, and bpm and measures must be strictly greater than zero; missing fields, non-numeric strings, non-finite numbers, and non-positive tempo or bar count return invalid_input and are never charged. On success the response echoes the rounded inputs, sets time_signature to the canonical numerator-slash-denominator string, reports seconds_per_beat, seconds_per_measure, beats_total, total_seconds, and total_milliseconds, then splits the same length into hours, minutes, and leftover seconds with a duration clock such as 1:04 or 0:57.6. Formula restates total_seconds equals measures times beats_per_bar times sixty over bpm. Pricing is a flat $0.002 per successful request with unit item.

Practical tips, limits, and related searches

Prefer sending numbers rather than pre-formatted strings when you control the client; string numbers are accepted only when they match a strict finite numeric pattern. Common studio checkpoints are easy to memorize: thirty-two bars of four-four at one hundred twenty BPM is one minute four seconds; sixteen bars of four-four at sixty BPM is the same length because half the bars at half the tempo cancel; a waltz chorus of forty-eight bars in three-four at ninety BPM is one minute thirty-six seconds. Prefer this capability when the grid is already known; if your source is a free-time recording without a click, detect or tap BPM first, then count bars. Keep BPM and measure count inside the published absolute range so the reciprocal beat duration stays finite in IEEE double precision on the Worker and in the browser. When teaching, pair a positive happy path with a deliberate zero or negative tempo and a zero bar count to demonstrate the hard invalid_input path. This landing targets people searching for a song duration calculator, a music duration calculator from BPM and bars, or total song length from time signature and measures; it is not a delay-time table, not a MIDI ticks-per-quarter converter, and not a real-time metronome audio generator. Failed tasks that return invalid_input do not consume prepaid balance, which keeps exploratory scripts cheap when learners deliberately probe edge cases. Round-trip checks are straightforward: recompute measures times beats_per_bar times sixty divided by bpm and confirm it equals total_seconds within twelve-decimal rounding, then confirm that minutes and leftover seconds reassemble to the same total and that the duration string matches the clock split.