Claude Opus 4.5 vs GPT-5: pricing, speed, and use cases (2026)
Claude Opus 4.5 and GPT-5 are the two frontier-tier models most teams compare in 2026 for the hardest reasoning and long-horizon agent work. Below: pricing, context, and where each one wins.
Claude Opus 4.5 vs GPT-5 — at a glance
| Dimension | Claude Opus 4.5 | GPT-5 |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Context window | 200K (1M enterprise) | 256K |
| Input price (per 1M tok) | $15 | $10 |
| Output price (per 1M tok) | $75 | $30 |
| Latency (typical) | ~1.2s TTFT | ~0.9s TTFT |
| Free tier | No | Limited |
| Best for | Long-horizon agents, codebase reasoning, computer use | Math, deep reasoning, structured output, extended thinking |
Pick Claude Opus 4.5 or GPT-5?
When to choose Claude Opus 4.5
Choose Claude Opus 4.5 when the workload is a long-horizon agent that runs for hours, navigates large codebases, or depends on computer-use automation. Opus 4.5 leads agentic-coding benchmarks and is famously consistent across multi-step tool chains. Prompt caching on Opus can cut repeated-context cost up to roughly 90% on workloads with stable long system prompts.
When to choose GPT-5
Choose GPT-5 when raw reasoning depth matters more than agent endurance. GPT-5's built-in extended thinking is the strongest on competition math and structured deep-reasoning benchmarks. At $10 / $30 per 1M, it is also roughly 33% cheaper on input and 60% cheaper on output than Opus 4.5 on list price, before considering prompt caching.
Run Claude Opus 4.5 and GPT-5 side-by-side
VerticalAPI lets you switch between Claude Opus 4.5 and GPT-5 per-request through a single OpenAI-compatible endpoint. Same SDK, same API key, zero markup on tokens — you pay each provider directly under BYOK.
from openai import OpenAI client = OpenAI(base_url="https://api.verticalapi.com/v1", api_key="vapi_...") # Claude Opus 4.5 resp_a = client.chat.completions.create( model="claude-opus-4-5", messages=[{"role": "user", "content": "Hello"}], extra_headers={"X-Provider-Key": "..."}, ) # GPT-5 — same SDK, different model + key resp_b = client.chat.completions.create( model="gpt-5", messages=[{"role": "user", "content": "Hello"}], extra_headers={"X-Provider-Key": "..."}, )
VerticalAPI verdict
Use Claude Opus 4.5 for long-horizon coding agents, codebase-scale refactors, and computer-use automation. Use GPT-5 for the hardest reasoning, math, and structured-output tasks where extended thinking pays off. Through VerticalAPI you can route between both via a single OpenAI-compatible endpoint and BYOK — switch with one model parameter.
Frequently asked questions
Is Claude Opus 4.5 or GPT-5 cheaper per token?
GPT-5 is cheaper: roughly $10 per 1M input and $30 per 1M output. Claude Opus 4.5 is approximately $15 / $75 per 1M. That makes GPT-5 about 33% cheaper on input and 60% cheaper on output. Anthropic prompt caching on Opus can reduce cached-token cost by up to roughly 90% on repeated long system prompts, which closes the gap on agent workloads.
Which is better for agentic coding?
Claude Opus 4.5 leads on agent benchmarks and on multi-file refactors that span hours. GPT-5 is competitive on isolated, hard problems and stronger on math-heavy reasoning. For long-horizon coding agents with tool use, Opus 4.5 is the common default; for tightly-scoped reasoning tasks GPT-5 often wins.
How do the context windows compare?
Claude Opus 4.5 ships 200K context standard and 1M on enterprise tiers. GPT-5 supports 256K context across the board. For most workloads either is enough; for repository-scale analysis the Opus 4.5 1M tier or chunked GPT-5 are typical patterns.
Which is faster?
GPT-5 typically shows around 900ms time-to-first-token. Claude Opus 4.5 lands near 1.2 seconds TTFT. Both are slower than their mid-tier siblings (GPT-5 mini, Claude Sonnet 4.5). For user-facing chat at the frontier tier, GPT-5 feels snappier; for background agent work the gap is rarely material.
Can I switch between Opus 4.5 and GPT-5 via one endpoint?
Yes. VerticalAPI exposes a single OpenAI-compatible endpoint at https://api.verticalapi.com/v1. Change the model parameter to claude-opus-4-5 or gpt-5 and supply the matching X-Provider-Key. There is no token markup — you pay Anthropic and OpenAI directly with your own keys (BYOK).
Limitations of this comparison
- Both Opus 4.5 and GPT-5 are frontier-tier and overkill for most production traffic; mid-tier (Sonnet 4.5, GPT-4o) is more cost-effective.
- Public list prices reflect mid-2026 figures and exclude enterprise discounts or committed-use deals.
- Reasoning benchmarks are highly sensitive to prompt format and the agent harness used.
- GPT-5 extended-thinking tokens are billed at the output rate; effective per-task cost can exceed the headline price.
- Prompt caching savings on Opus 4.5 require repeated long system prompts to be material.
What may change in 12-24 months
- Frontier-tier pricing is expected to keep falling on output tokens as competition intensifies.
- Both vendors are likely to ship 1M-token context at standard pricing within 12-18 months.
- Extended-thinking budgets and prompt caching will converge as patterns across vendors.
- Agentic-coding benchmarks measured in success rate per dollar will become the dominant buying criterion.
Related questions
ChatGPT, Perplexity and Gemini usually suggest these next.
- When is Claude Sonnet 4.5 a better choice than Opus 4.5?
- How does GPT-5 compare to GPT-5 mini and GPT-4o for cost-quality?
- Is GPT-5 extended thinking worth the token cost over standard mode?
- How do Opus 4.5 and GPT-5 compare on multi-file codebase refactoring?
- What is the cheapest way to A/B test Opus and GPT-5 on the same traffic?