Milliseconds to seconds
Convert milliseconds to seconds by dividing by 1000. Includes the Unix timestamp trap that puts dates in 1970 or 55000 AD.
Runs in your browser
The formula
seconds = milliseconds ÷ 1000The timestamp trap
This conversion exists mostly because two of the most common time representations in software differ by exactly this factor, and mixing them produces dates that are absurd rather than merely wrong.
| Source | Unit | 1 January 2026 looks like |
|---|---|---|
| Unix time, POSIX, most APIs, Go, Python | seconds | 1767225600 |
JavaScript Date.now(), Java currentTimeMillis() | milliseconds | 1767225600000 |
Feeding one into something expecting the other:
- Milliseconds read as seconds puts the date about 30,000 years in the future.
- Seconds read as milliseconds puts it in January 1970, a few weeks after the epoch.
Both failures are loud, which is the one merciful thing about them. The rule of thumb: a current Unix timestamp in seconds is 10 digits; in milliseconds it is 13. If you are staring at a number and cannot tell, count the digits. See the timestamp converter.
Quick reference
| Milliseconds | Seconds |
|---|---|
| 1 ms | 0.001 s |
| 10 ms | 0.01 s |
| 100 ms | 0.1 s |
| 500 ms | 0.5 s |
| 1000 ms | 1 s |
| 60,000 ms | 60 s |
| 3,600,000 ms | 3600 s |
Latency and human perception
Milliseconds are the unit of interface responsiveness, and the thresholds are well established:
| Milliseconds | Feels like | |
|---|---|---|
| Frame at 60 fps | 16.7 ms | — |
| Instant | < 100 ms | direct manipulation |
| Noticeable | 100–300 ms | responsive but not instant |
| Flow broken | > 1000 ms | waiting |
| Attention lost | > 10,000 ms | gone |
| Network | Typical round trip |
|---|---|
| Same city | 5–20 ms |
| Same continent | 20–80 ms |
| Transatlantic | 70–120 ms |
| Transpacific | 100–200 ms |
| Geostationary satellite | 500–600 ms |
The transpacific figure is close to the speed of light in fibre and cannot be engineered away, which is why edge caching exists.
Finer units
| Unit | Seconds |
|---|---|
| Millisecond (ms) | 10⁻³ |
| Microsecond (µs) | 10⁻⁶ |
| Nanosecond (ns) | 10⁻⁹ |
A nanosecond is about 30 cm of light travel — which is why signal timing inside a computer is a question of physical distance.
Estimating in your head
Move the decimal point three places. 2500 ms is 2.5 s.