UUID Version 1 Generator
UUIDv1 • Gregorian Timestamp & Simulated MAC
00000000-0000-0000-0000-000000000000
Enclose:
Generate Bulk UUIDs
0 msReady
Max 5,000
Formatting & Structure
Ready
No batch active1-click copy available on each row
Legacy Standard•RFC 9562 Section 5.1 / RFC 4122
UUID Version 1 Technical Specification (Gregorian Timestamp)
UUIDv1 generates 128-bit identifiers based on a 60-bit Gregorian calendar timestamp (measuring 100-nanosecond intervals since October 15, 1582) combined with a clock sequence and node identifier (historically the machine 48-bit MAC address).
Bitfield Layout & Binary Structure
Detailed 128-bit byte distribution according to RFC standards.
| Field Name | Bit Range | Purpose & Description |
|---|---|---|
| time_low | 32 bits (0-31) | Low 32 bits of 60-bit Gregorian timestamp. |
| time_mid | 16 bits (32-47) | Middle 16 bits of 60-bit Gregorian timestamp. |
| time_hi_and_ver | 16 bits (48-63) | 4 bits version (0001) + top 12 bits of Gregorian timestamp. |
| clock_seq | 16 bits (64-79) | 2 bits variant (10) + 14 bits clock sequence counter. |
| node | 48 bits (80-127) | Node identifier (simulated multicast random address). |
✓
Advantages & Strengths
- •Guarantees global uniqueness when paired with unique network interface MAC hardware.
- •High-resolution timestamping down to 100-nanosecond intervals.
!
Considerations & Trade-offs
- •Privacy risk: original RFC 4122 implementation exposes physical MAC address of the host machine.
- •Not lexicographically sortable because the lowest bits of timestamp appear first (time_low).
Best Recommended For
- →Legacy distributed architectures designed around RFC 4122 v1.
- →Cassandra and ScyllaDB TimeUUID columns where v1 byte order is built into storage engines.
When to Avoid
- ✕Modern web and cloud architectures (use UUIDv7 instead for cleaner timestamp sorting and zero MAC exposure).
Code Implementation Examples
Python Standard LibraryPython
import uuid
id = uuid.uuid1()
print(id)Frequently Asked Questions
Does this generator leak my real computer MAC address?▼
No. To preserve your privacy per RFC 9562 recommendations, our generator uses a cryptographically random 48-bit multicast node address rather than your physical network interface address.
Why does UUIDv1 sort out of order?▼
In UUIDv1, the least significant timestamp bits (time_low) appear at the beginning of the string, while the most significant bits appear in the third group. Therefore, simple string sorting does not order v1 UUIDs chronologically.