⏱️ Time Unit Converter
How to Use
Type a value into any field (decimals welcome — 1.5 hours works) and the other seven fields update instantly to 4 decimal places, no button needed. The most recently edited field is the source of truth; clear it to start over.
The SLA Table: What "Nines" Cost in Real Time
One of the most practical uses of time-unit math is translating availability percentages into allowed downtime. A 365-day year is 8,760 hours = 525,600 minutes, so:
| Availability | Downtime per year | Per month (30 d) |
|---|---|---|
| 99% ("two nines") | 87.6 hours | 7.2 hours |
| 99.9% | 8.76 hours | 43.2 minutes |
| 99.99% | 52.6 minutes | 4.3 minutes |
| 99.999% ("five nines") | 5.26 minutes | 26 seconds |
Next time a vendor promises "three nines," you'll know that's a full working day of outage per year — this converter lets you sanity-check any such claim in seconds.
Conventions Behind the Numbers
- Months and years are fixed here: 1 month = 30 days, 1 year = 365 days — the standard engineering simplification. For "what date is 3 months from now," use our Date Calculator instead; calendar months vary from 28 to 31 days.
- Milliseconds are the developer's unit:
setTimeout(fn, 3000)is 3 seconds; a 250 ms API budget is a quarter second. Unix timestamps in JavaScript are milliseconds, while most other languages use seconds — a classic ×1000 bug source. - The 2,080-hour work year: 40 hours × 52 weeks is the standard full-time-equivalent figure used in salary and staffing math (before subtracting holidays).
- No leap seconds: the 27 leap seconds inserted since 1972 aren't part of any fixed-coefficient conversion — only timekeeping systems care.
Frequently Asked Questions
Why does "1 month" here disagree with my calendar?
This page uses a fixed 30-day month for ratio conversion. Calendar months vary in length, so date-anchored questions belong in the Date Calculator.
Can I enter compound values like 1 h 30 m?
Reduce to a single unit first — 1.5 hours or 90 minutes. For hh:mm:ss arithmetic (adding and subtracting clock times), use our Time Calculator.
How precise are the results?
Four decimal places. Very small results may display as 0.0000 — switch to a smaller unit (milliseconds) to read them meaningfully.
Why do finance people use a 360-day year?
Legacy day-count conventions like 30/360 made interest math tractable before computers, and they persist in bonds and loans. The same duration can accrue different interest under 30/360 vs ACT/365 — always check which convention a contract specifies.