About

Time unit conversion errors cascade through scheduling systems, billing platforms, and scientific data pipelines. A misplaced decimal when converting 86400 s (one day) into fractional days corrupts downstream calculations - cron jobs fire at wrong intervals, SLA reports misstate uptime, and experiment timestamps drift. This converter decomposes any number of seconds into its exact breakdown of days, hours, minutes, and remaining seconds using integer division by the constant 86400 s/day. It handles values from zero up to billions of seconds without floating-point rounding artifacts.

The tool operates bidirectionally. Enter seconds to receive a full time breakdown, or enter days, hours, minutes, and seconds to receive the total in seconds. All arithmetic is exact integer math where possible, with decimal precision preserved for sub-second inputs. Note: this converter assumes 1 day = 86400 s exactly. It does not account for leap seconds, which occur irregularly and add 1 s roughly every 18 months.

Formulas

The conversion from seconds to a composite time breakdown uses successive integer division and modulo operations. Given total seconds S:

d = floor(S86400)

h = floor(S mod 864003600)

m = floor(S mod 360060)

s = S mod 60

The reverse (composite to total seconds):

S = d × 86400 + h × 3600 + m × 60 + s

Where d = days, h = hours, m = minutes, s = remaining seconds, and 86400 = 24 × 60 × 60 s/day.

Reference Data

Time Period	Seconds	Minutes	Hours	Days
1 Minute	60	1	0.0167	6.944×10⁻⁴
1 Hour	3,600	60	1	0.04167
1 Day	86,400	1,440	24	1
1 Week	604,800	10,080	168	7
1 Fortnight	1,209,600	20,160	336	14
30-Day Month	2,592,000	43,200	720	30
31-Day Month	2,678,400	44,640	744	31
1 Quarter (91 d)	7,862,400	131,040	2,184	91
1 Common Year	31,536,000	525,600	8,760	365
1 Leap Year	31,622,400	527,040	8,784	366
1 Julian Year	31,557,600	525,960	8,766	365.25
1 Decade	315,360,000	5,256,000	87,600	3,650
1 Century	3,153,600,000	52,560,000	876,000	36,500
1 Millennium	31,536,000,000	525,600,000	8,760,000	365,000
1 Sidereal Day	86,164.1	1,436.07	23.9345	0.99727
1 Synodic Month	2,551,443	42,524.05	708.73	29.5306
Mars Sol	88,775.24	1,479.59	24.66	1.02749
Planck Time	5.391×10⁻⁴⁴	8.985×10⁻⁴⁶	1.498×10⁻⁴⁷	6.24×10⁻⁴⁹
Age of Universe	4.35×10¹⁷	7.25×10¹⁵	1.21×10¹⁴	5.03×10¹²

Frequently Asked Questions

The SI definition of a day is exactly 86,400 seconds. Leap seconds are irregular corrections applied to UTC (roughly 27 since 1972) and cannot be predicted algorithmically. For engineering, scheduling, and general-purpose conversion, the 86,400 s/day constant is the universally accepted standard. If you work in precision timekeeping (GPS, radio astronomy), you must consult the IERS Bulletin C for leap second schedules.

JavaScript uses IEEE 754 double-precision floats, which provide exact integer representation up to 2^53 − 1 (9,007,199,254,740,991). That is approximately 1.04 × 10^11 days, or about 285 million years. Beyond this threshold, integer precision degrades and results may be off by 1 or more seconds.

Fractional seconds are preserved in the final "seconds" component of the breakdown. For example, 90061.75 seconds yields 1 day, 1 hour, 1 minute, and 1.75 seconds. The days, hours, and minutes components are always whole integers; only the seconds remainder carries the decimal portion.

This tool accepts non-negative values only. Negative time intervals are mathematically valid but semantically ambiguous in a unit converter context. If you need to represent a time in the past, convert the absolute value and note the direction separately.

A mean solar day is defined as exactly 86,400 SI seconds. A sidereal day (one full rotation of Earth relative to distant stars) is approximately 86,164.1 seconds - roughly 3 minutes and 56 seconds shorter. This difference accumulates to one full extra sidereal day per year, which is why there are about 366.25 sidereal days in a year but only 365.25 solar days.

Divide your seconds value by 86,400. For example, 129,600 ÷ 86,400 = 1.5 days. This tool shows both the fractional day value and the full integer breakdown (1 day, 12 hours, 0 minutes, 0 seconds) for convenience.