How do I get Unix timestamp seconds in C with time.h?
Use time(NULL) from time.h. It returns epoch seconds in time_t and is portable across common C runtimes.
C Get Unix Timestamp with time.h in 2026
If you searched for c get unix timestamp, you usually need one dependable integer to pass between APIs, logs, queues, and SQL tables. In 2026, the most stable C approach is still to use time.h for seconds, then convert to milliseconds only when your contract explicitly needs 13-digit precision.
Production timestamp bugs in C are often unit or type bugs. Keep epoch values in UTC, make conversions explicit, and use 64-bit integer math when computing milliseconds. This keeps C services aligned with JavaScript and backend systems that parse epoch values differently.
Copy-ready C snippets
Epoch seconds with time.h
#include <time.h> time_t epoch_seconds = time(NULL);
Epoch milliseconds (64-bit)
#include <time.h> #include <stdint.h> struct timespec ts; clock_gettime(CLOCK_REALTIME, &ts); int64_t epoch_ms = (int64_t)ts.tv_sec * 1000 + (int64_t)ts.tv_nsec / 1000000;
Related EpochConverter pages
For adjacent C intent, see C get Unix time, C get Unix timestamp, and Unix timestamp in C. To decode values from logs, use Unix timestamp to date.
Need quick two-way conversion while debugging? Open the main epoch converter tool.
Related developer tool
If your C timestamp checks run in scheduled workers, validate job cadence with Cron Expression Builder.
Frequently Asked Questions
How do I compute milliseconds safely in C?
Use clock_gettime and combine tv_sec and tv_nsec into a signed 64-bit integer to avoid truncation on large values.
Why does 64-bit handling matter for timestamps?
Some platforms historically used 32-bit time_t. Using 64-bit-safe patterns avoids overflow and improves long-term compatibility in 2026 systems.
Should timestamp values be stored in local time?
No. Store raw UTC epoch integers and format local time only when rendering to users.