Last Updated: 3/9/2026

Comparison with UUID

How Nano ID compares to UUID v4, and when to use each.

Quick Comparison

Collision Probability

Both Nano ID and UUID v4 have similar collision safety:

For there to be a one in a billion chance of duplication, 103 trillion version 4 IDs must be generated.

Entropy Comparison

UUID v4: 122 bits of entropy

• 128 bits total
• 6 bits reserved for version and variant
• = 122 random bits

Nano ID: 126 bits of entropy

• 21 characters × log₂(64) = 126 bits
• All bits are random
• = 126 random bits

Conclusion: Nano ID has slightly more entropy despite being shorter.

Size Comparison

String Length

Nano ID: 21 characters

V1StGXR8_Z5jdHi6B-myT

UUID v4: 36 characters

a3bb189e-8bf9-3888-9912-ace4e6543002

Difference: Nano ID is 41% shorter

Why Nano ID Is Shorter

Nano ID uses a larger alphabet (64 characters vs 16), packing more information per character.

Math:

• UUID: 16 possible values per character = 4 bits/char
• Nano ID: 64 possible values per character = 6 bits/char
• To encode 122 bits: UUID needs 31 chars, Nano ID needs 21 chars

Bundle Size

Nano ID: 118 bytes (minified + brotlied)

npm install nanoid
# + nanoid@5.0.0 (118 bytes)

uuid/v4: 423 bytes (minified + brotlied)

npm install uuid
# + uuid@9.0.0 (423 bytes for v4 only)

Difference: Nano ID is 72% smaller

Database Storage

Storing 1 million IDs:

Nano ID: 21 MB UUID v4: 36 MB

Savings: 15 MB per million records

For 100 million records: 1.5 GB saved

URL Safety

Nano ID: URL-Safe by Default

https://example.com/posts/V1StGXR8_Z5jdHi6B-myT

✅ No encoding needed ✅ Works in URLs, filenames, HTML attributes ✅ Double-click selectable

UUID: Not URL-Safe

https://example.com/posts/a3bb189e-8bf9-3888-9912-ace4e6543002

⚠️ Hyphens can be problematic in some contexts:

• Some systems treat hyphens as word boundaries
• Double-clicking may not select the full ID
• Some parsers may split on hyphens

Workaround: Remove hyphens

https://example.com/posts/a3bb189e8bf9388899912ace4e6543002

But now it’s 32 characters (still longer than Nano ID’s 21).

Performance

Benchmark results (ops/sec, higher is better):

crypto.randomUUID          7,619,041 ops/sec  (native UUID)
uuid v4                    7,436,626 ops/sec  (uuid package)
nanoid                     3,693,964 ops/sec

UUID is ~2x faster due to native implementation.

When Performance Matters

For most applications, performance difference is negligible:

• Generating 1000 IDs with Nano ID: ~0.27ms
• Generating 1000 IDs with UUID: ~0.13ms
• Difference: 0.14ms

Performance becomes relevant when:

• Generating millions of IDs per second
• Extremely latency-sensitive (sub-millisecond)
• Running on constrained devices

In these cases, consider:

1. Batch generation
2. Pre-generating IDs
3. Using native crypto.randomUUID() (if UUID format is acceptable)

Format and Readability

Nano ID

V1StGXR8_Z5jdHi6B-myT

✅ Compact ✅ Mixed case (visually distinct) ⚠️ No inherent structure (can’t extract metadata)

UUID v4

a3bb189e-8bf9-3888-9912-ace4e6543002

✅ Standardized format (RFC 4122) ✅ Hyphens group digits (some find more readable) ✅ Version bits indicate type ⚠️ Longer ⚠️ Lowercase only (less visually distinct)

When to Use Each

Use Nano ID When:

✅ You want shorter IDs

• URLs, slugs, short links
• Database with millions of records
• Mobile apps (smaller bundle size)

✅ You need URL-safe IDs

• RESTful API paths
• Filenames
• HTML attributes

✅ Bundle size matters

• Frontend applications
• Serverless functions
• Embedded systems

✅ You’re starting a new project

• No legacy UUID dependencies
• Greenfield development

Use UUID When:

✅ You need maximum performance

• Generating millions of IDs/second
• Can use native crypto.randomUUID()

✅ You need standardization

• Interoperability with other systems
• Industry standards require UUID
• Existing infrastructure uses UUID

✅ You need specific UUID versions

• UUID v1 (timestamp-based)
• UUID v5 (namespace + name hashing)
• UUID v6/v7 (sortable)

✅ Legacy system compatibility

• Database already uses UUID
• APIs expect UUID format
• Migration cost is too high

Migration from UUID to Nano ID

Can I Switch?

Yes, but consider:

Easy migration:

• New records use Nano ID
• Old records keep UUID
• Both formats coexist

function getId(record) {
  // Detect format by length
  return record.id.length === 36 ? 'uuid' : 'nanoid'
}

Difficult migration:

• Foreign key relationships
• Hardcoded ID format validation
• External systems expect UUID

Hybrid Approach

import { nanoid } from 'nanoid'
import { v4 as uuidv4 } from 'uuid'
 
function createUser(data) {
  return {
    id: nanoid(), // New internal ID format
    uuid: uuidv4(), // Legacy UUID for external APIs
    ...data
  }
}

Can I Use Both?

Yes! Many projects use:

• Nano ID: Internal IDs, URLs, new features
• UUID: External APIs, legacy systems, specific UUID versions

import { nanoid } from 'nanoid'
import { v4 as uuidv4 } from 'uuid'
 
const internalId = nanoid() // Short, for internal use
const externalId = uuidv4()  // Standard, for API responses

Other UUID Versions

Nano ID is comparable to UUID v4 (random). For other versions:

UUID v1 (timestamp + MAC address)

• ✅ Sortable by time
• ❌ Reveals MAC address (privacy issue)
• ❌ Not random (predictable)

UUID v5 (namespace + name SHA-1 hash)

• ✅ Deterministic (same input = same UUID)
• ❌ Not random
• Use case: Generating IDs from existing data

UUID v6/v7 (sortable + random)

• ✅ Time-ordered
• ✅ Random component
• ✅ Better for databases (index-friendly)
• ⚠️ Still 36 characters

For sortable IDs, consider:

• ULID: Sortable, 26 characters (shorter than UUID)
• Custom: Timestamp + Nano ID

import { nanoid } from 'nanoid'
 
function sortableId() {
  return Date.now().toString(36) + nanoid(10)
}
// => "l8r9x4kV1StGXR8_Z5"

Summary

Choose Nano ID for:

• Shorter IDs (21 vs 36 chars)
• URL-safe format
• Smaller bundle size
• Modern projects

Choose UUID v4 for:

• Maximum performance (native implementation)
• Industry standards
• Legacy compatibility
• Specific UUID version needs

Both are secure and have similar collision probability. The choice is mostly about format, size, and ecosystem compatibility.

Related

• Core API - How to use Nano ID
• Security Details - Security deep dive
• Performance Benchmarks - Detailed performance comparison