Claude 4.5 vs ChatGPT-5 2026: Full Benchmark Comparison
The Claude 4.5 family (Opus 4.5, Sonnet 4.5) and OpenAI's ChatGPT-5 are the two most-compared generalist LLMs in production today. Both launched within six months of each other (Claude 4.5 in November 2025, GPT-5 in August 2025), both positioned as flagship tier, and both serve as defaults in major coding tools. This comparison runs them side-by-side across 10 benchmarks — SWE-Bench Verified, GPQA Diamond, MMLU, HumanEval, MATH, LiveCodeBench, long-context recall, vision, reasoning, and real-world coding task success — plus pricing, API compatibility, and the specific decision matrix. All numbers verified against third-party benchmark aggregators as of April 24, 2026. TokenMix.ai routes both through the same OpenAI-compatible endpoint.
Snapshot note (2026-04-24): This article compares the Claude 4.5 ↔ GPT-5 generation as of spring 2026. Benchmark percentages are composites of launch-post vendor numbers and third-party aggregators (Vellum / Artificial Analysis). For production decisions today, verify against the latest generation (Opus 4.7 / GPT-5.4 or the April 23, 2026 GPT-5.5 release) — quality gap patterns often persist across versions but absolute scores shift.
Side-by-Side Benchmark Table
Benchmark
Claude Opus 4.5
Claude Sonnet 4.5
GPT-5
MMLU
91%
88%
92%
GPQA Diamond
92%
87%
87%
HumanEval
92%
89%
93%
SWE-Bench Verified
78%
72%
54%
MATH-500
93%
90%
90%
LiveCodeBench
86%
82%
82%
Long-context recall @ 200K
92%
88%
88% (at 128K)
Vision MMBench
88%
85%
87%
Reasoning depth
Strong
Good
Good
Tool use (BFCL)
92%
89%
90%
Winners: Opus 4.5 wins coding/reasoning/long-context. GPT-5 wins marginally on MMLU and HumanEval. Sonnet 4.5 positioned as mid-tier value.
Pricing Comparison
Model
Input $/MTok
Output $/MTok
Blended (80/20)
Claude Opus 4.5
$5.00
$25.00
$9.00
Claude Sonnet 4.5
$3.00
5.00
$5.40
GPT-5
$2.50
5.00
$5.00
GPT-5-mini
$0.25
$2.00
$0.60
GPT-5-nano
$0.05
$0.40
$0.12
GPT-5 is cheaper than Claude Sonnet 4.5 by ~7% (nominal), similar on output. GPT-5 has mini/nano tiers for aggressive cost reduction; Claude's equivalent is Haiku family.
Coding: Where Each Wins
Specific coding tasks:
Task
Opus 4.5
GPT-5
Winner
Single-file code generation
90%
88%
Opus
SWE-Bench Verified (multi-file)
78%
54%
Opus by 24pp
Code review / explanation
Strong
Strong
Tie
Inline completion latency
Medium
Fast
GPT-5
Refactoring
Strong
Moderate
Opus
Test generation
Strong
Good
Opus
Debugging complex errors
Strong
Moderate
Opus
Opus 4.5 is meaningfully stronger for agentic coding (Cline, Aider, Claude Code). GPT-5 holds inline completion speed advantage (lower TTFT).
Reasoning: The Gap
On benchmarks requiring multi-step logical reasoning:
Task
Opus 4.5
GPT-5
Formal math proofs
85%
78%
Chain-of-thought problems
92%
88%
Graduate science (GPQA)
92%
87%
Causal inference
Strong
Good
GPT-5's equivalent dedicated reasoning variant is GPT-5.4 Thinking (not 5 base). If your workload is reasoning-heavy, compare Opus 4.5 vs GPT-5.4 Thinking, not base GPT-5.
Multimodal: Vision Capability
Vision task
Opus 4.5
GPT-5
Chart / diagram understanding
Good
Good
OCR accuracy
Strong
Strong
UI screenshot analysis
Best (3.0MP)
Good (2.5MP)
Artistic interpretation
Good
Better
Document Q&A
Strong
Strong
Minor edges each way. For high-DPI screenshots and UI analysis, Opus 4.5 (3.0MP cap). For creative/artistic image analysis, GPT-5.
Decision Matrix
Your priority
Pick
Why
Coding agent / SWE-Bench
Opus 4.5
+24pp advantage
General chat at low cost
GPT-5-mini or nano
10-50× cheaper
Long-context analysis (>128K)
Opus 4.5
200K native vs 128K
Premium research
Opus 4.5
Better reasoning
Creative writing
GPT-5
Slightly more natural
Multilingual
Opus 4.5
Better Asian languages
Cost-constrained production
GPT-5-mini
Best value
Already on Anthropic ecosystem
Opus 4.5 / Sonnet 4.5
Integration
Already on OpenAI ecosystem
GPT-5 family
Integration
Note: for new production as of April 2026, consider skipping both and starting with Claude Opus 4.7 (87.6% SWE-Bench) or GPT-5.4 — both are quality upgrades over 4.5/5 at similar pricing.
FAQ
Are Claude 4.5 and ChatGPT-5 still relevant in April 2026?
Yes as stable production options. Both are 12-18 months old but haven't been deprecated. For new builds: Claude Opus 4.7 or GPT-5.4 are better; for existing production on 4.5/5, no urgency to migrate unless specific quality issue.
Is ChatGPT-5 the same as GPT-5?
Same model, different naming. "ChatGPT-5" is the marketing name for the consumer product and API model family; "GPT-5" is the precise technical name. OpenAI uses both interchangeably.
Which has better Chinese language support?
Both strong. Claude Opus 4.5 edges slightly for classical/literary Chinese; GPT-5 for modern casual Chinese. For most business applications they're tied.
Does the tokenizer tax apply to Claude 4.5?
No — the tokenizer update was introduced in Opus 4.7. Claude 4.5 uses the older, more efficient tokenizer. This is actually a reason some teams pinned on 4.5 instead of upgrading to 4.7. See Opus 4.7 review.
What about multimodal audio?
Claude doesn't have audio API yet. GPT-5 (and GPT-4o's realtime variant) have voice capabilities. For voice agents, OpenAI.
Can I use both via the same OpenAI SDK?
Yes — through TokenMix.ai or similar OpenAI-compatible gateway. Swap model ID: anthropic/claude-opus-4-5 vs openai/gpt-5. Zero code changes.
How does this compare to OpenAI's latest vs Anthropic's latest?
See current state: Claude Opus 4.7 vs GPT-5.4. Opus 4.7 extends the coding lead (+29pp SWE-Bench Verified vs GPT-5.4). Gap is even wider than 4.5 vs 5.
