Base62 vs Base64: The Definitive Performance, Length, and Compatibility Showdown

Choosing an encoding scheme is rarely just about compression; it's about compatibility. The core question of base62 vs base64 boils down to whether you prioritize the efficiency of standard internet protocols (Base64) or the robustness of purely alphanumeric output (Base62). For URL slugs, database IDs, and short tokens, Base62 often wins.

While Base64 uses 64 characters ([A-Z, a-z, 0-9, +, /, =]), Base62 strictly uses 62 alphanumeric characters ([A-Z, a-z, 0-9]), eliminating the '+', '/', and padding character ('=') that cause conflicts in web environments.

Section 1: The Core Trade-Offs—Length vs. Universality

The primary reason the debate of base62 vs base64 exists is the length of the encoded output. Base64 encodes 3 bytes into 4 characters, resulting in a 33.3\% expansion. Base62 achieves a slightly higher compression rate, as it packs more bits per character. However, this non-4-bit alignment often requires custom implementations, unlike the native support for Base64 found in almost every programming language.

# Length Comparison: 128 bits of binary data (16 bytes)

# Base64 output length (4/3 expansion):
# ceil(16 * 4 / 3) = 22 characters + potential padding (1 or 2 '=')
# Example: Xw0sYl89jC209s0x/Q==

# Base62 output length (approx 6/5 expansion):
# ceil(128 / log2(62)) ≈ 21.3 characters
# Example: HjsT9GzQ2T7v4R3q7T4H
            

Section 2: The Compatibility Killer—Why Base62 is Safer

The standard Base64 character set includes '+' and '/'. These characters are reserved in URLs and must be URL-encoded (e.g., '+' becomes '\%2B'), defeating the purpose of a compact string. Furthermore, the mandatory padding character ('=') breaks many parsers and database storage schemas. The primary Base62 benefits stem from eliminating these problematic characters entirely.

# Base64 (Standard) issues in URLs/Databases
URL = "example.com/id/Xw0sYl89jC209s0x/Q=="
# Problems: '/', '+', '=' require URL encoding/escaping.

# Base62 Solution
URL = "example.com/id/HjsT9GzQ2T7v4R3q7T4H"
# Alphanumeric only—no URL encoding needed.
            

Expert Insight: Base62 is Optimized for Short Tokens

If you are generating short, human-readable IDs (like those used by YouTube or Imgur), the slightly shorter output length of Base62 combined with its guaranteed alphanumeric output provides undeniable advantages over Base64.

Section 3: Beyond Base64—The base64 vs base85 Question

If Base64's 33\% expansion is too great, you might look at Base85 (Ascii85). The comparison of base64 vs base85 reveals that Base85 encodes 4 bytes into 5 characters, achieving only a 25\% expansion. This makes Base85 the clear winner for minimum length, particularly for large blocks of data. However, its use of more complex characters ('!'-'z') makes it even less URL-friendly than Base64.

E-E-A-T Performance: Decoding Speed and Length Benchmarks

Does the higher compression ratio of Base85 translate to faster decoding? And how much shorter is Base62 in practice?

Conclusion: Base64 for Standard, Base62 for Web Tokens

Use standard Base64 when you need maximum universal compatibility (e.g., HTTP Basic Auth, Data URIs). But if your primary concern is creating short, clean, URL/database-safe tokens, Base62 is the superior and cleaner choice, provided you use a reliable library. If raw length reduction is all that matters, consider Base85.