Time Calculator — Complete Guide
Time does not count in tens. There are 60 seconds in a minute, 60 minutes in an hour and 24 hours in a day, so the moment a calculation involves more than one of these units, the arithmetic stops being intuitive. This calculator takes two durations expressed in days, hours, minutes and seconds, adds or subtracts them, and handles all the carrying automatically.
What this calculator does
Fill in duration A and duration B — any combination of days, hours, minutes and seconds — and choose whether to add or subtract. The result appears as a normalised duration (seconds never exceed 59, minutes never exceed 59, hours never exceed 23 in the breakdown), alongside totals in pure hours, minutes, seconds and decimal days.
The method
total seconds = (days × 86400) + (hours × 3600) + (minutes × 60) + seconds
then days = total ÷ 86400, hours = total ÷ 3600, … with remainders carried
Working in one unit and converting back at the end is the only reliable way to do time arithmetic by hand, too — converting as you go is where most mistakes come from.
A worked example
A video edit needs 2h 45m 30s of footage and the exported file runs 1h 20m 50s over. Adding them: 2h 45m 30s + 1h 20m 50s = 4h 06m 20s. In totals: 4.106 hours, 246.3 minutes, 14,780 seconds, or 0.171 decimal days.
| Duration A | Duration B | A + B |
|---|
| 2h 45m 30s | 1h 20m 50s | 4h 06m 20s |
| 1d 3h 00m | 5h 45m | 1d 8h 45m |
| 0h 50m | 0h 20m | 0h 70m → 1h 10m |
Where this comes up
- Workouts — summing interval sets, or pace math across segments of a run.
- Media — playlist lengths, remaining recording time, edit timelines.
- Projects — adding up task estimates that were jotted down in minutes and hours.
- Travel — leg-by-leg journey times, including days of driving or multi-stop itineraries.
One convention to keep straight: this tool computes durations, not clock times. If you need to know when a shift ends given a start time and a length, or how much time passes between two events on the calendar, use the Hours Calculator or the Date Difference Calculator — they handle the calendar and midnight-crossing rules that durations deliberately ignore.
时间计算器完整使用指南
时间不是十进制的：一分钟 60 秒，一小时 60 分钟，一天 24 小时。只要算式里同时出现两种以上的单位，心算就容易出错。这个计算器把两段以天、时、分、秒表示的时长做加法或减法，进位自动处理。
这个计算器能做什么
分别填入时长 A 与时长 B——天、时、分、秒任意组合——选择加法或减法。结果会以规范化的时长呈现（秒不超过 59、分不超过 59），同时给出纯小时、纯分钟、纯秒与十进制天的总数。
计算方法
总秒数 = 天 × 86400 + 小时 × 3600 + 分钟 × 60 + 秒
再换算：天 = 总秒数 ÷ 86400，小时 = 总秒数 ÷ 3600……余数逐级进位
手工计算时同样只有一个可靠办法：先统一到最小单位，算完再换算回来——边算边换算正是大多数错误的来源。
算例演示
一段视频素材长 2 小时 45 分 30 秒，导出文件又多出 1 小时 20 分 50 秒。相加：2h 45m 30s + 1h 20m 50s = 4h 06m 20s。用总数表示：约 4.106 小时、246.3 分钟、14,780 秒，或 0.171 天。
| 时长 A | 时长 B | A + B |
|---|
| 2 时 45 分 30 秒 | 1 时 20 分 50 秒 | 4 时 06 分 20 秒 |
| 1 天 3 小时 | 5 小时 45 分 | 1 天 8 小时 45 分 |
| 50 分钟 | 20 分钟 | 70 分钟 → 1 小时 10 分 |
常见使用场景
- 健身——累加间歇组时长，或计算跑步各分段的配速时间。
- 影音——播放列表总长、剩余录制时长、剪辑时间线。
- 项目——把用分钟和小时随手记的任务估时累加起来。
- 出行——逐段累加行程时间，包括长途驾驶或多程中转。
有一个口径要分清：本工具算的是「时长」，不是「钟表时刻」。如果你想知道某个班次从几点上到几点、或日历上两个事件之间隔了多久，请用工时计算器或日期间隔计算器——它们处理的是跨零点和日历规则，这是时长计算刻意忽略的部分。