TokenMix Research Lab · 2026-04-24
Claude 4.5 vs ChatGPT-5 2026: Full Benchmark Comparison
Last Updated: 2026-04-24
Author: TokenMix Research Lab
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.
Table of Contents
- Confirmed vs Speculation
- Side-by-Side Benchmark Table
- Pricing Comparison
- Coding: Where Each Wins
- Reasoning: The Gap
- Multimodal: Vision Capability
- Decision Matrix
- FAQ
Confirmed vs Speculation
| Claim | Status | Source |
|---|---|---|
| Claude Opus 4.5 / Sonnet 4.5 released | Confirmed | Anthropic Nov 2025 |
| ChatGPT-5 / GPT-5 released | Confirmed | OpenAI August 2025 |
| Opus 4.5 SWE-Bench Verified 78% | Confirmed | Third-party |
| GPT-5 SWE-Bench Verified 50-55% | Confirmed | Benchmarks |
| GPT-5 cheaper on chat workloads | Yes (4o/5.4 family) | Pricing |
| Opus 4.5 better on multi-step coding | Confirmed | SWE-Bench |
| Both superseded by 4.7/5.4 | Yes for premium use | |
| GPT-5 better on general knowledge (MMLU) | Marginal |
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 | $15.00 | $5.40 |
| GPT-5 | $2.50 | $15.00 | $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.
Sources
- Anthropic Claude API
- OpenAI API
- Claude Opus 4.7 Review — TokenMix
- All ChatGPT Models — TokenMix
- Claude Sonnet vs Opus — TokenMix
- GPT-5.4 Thinking Review — TokenMix
By TokenMix Research Lab · Updated 2026-04-24