TokenMix Research Lab · 2026-05-29

Claude Opus 4.8 Review 2026: Pricing, Benchmarks, vs 4.7 and GPT-5.5

Claude Opus 4.8 Review 2026: Pricing, Benchmarks, vs 4.7 and GPT-5.5

Last Updated: 2026-05-29 Author: TokenMix Research Lab Data verified: 2026-05-28 launch announcement, Anthropic docs, AWS Bedrock release, Artificial Analysis

Anthropic shipped Claude Opus 4.8 on May 28, 2026 at the same $5 / $25 per million token rate as Opus 4.7. The upgrade is real but uneven: SWE-Bench Pro jumps +4.9 pts, GDPval-AA climbs 137 Elo, Terminal-Bench +8.5 pts — yet GPQA Diamond slips 0.6 pts and GPT-5.5 still wins Terminal-Bench at 78.2%. This review covers what to migrate, when, and where the new Fast Mode and Dynamic Workflows pricing actually pencils out.

The headline number for builders: Opus 4.8 is now 4x less likely than 4.7 to ship code with unflagged flaws, and its new Fast Mode runs 2.5x faster at three times less than Opus 4.7's fast tier. Pricing held flat. For anyone already running Claude Opus 4.7 in production, migration is a config-only change in most cases — no API-breaking changes, same context window, same tool surface.

Table of Contents

Quick Verdict

Statement Confidence Note
Release date is May 28, 2026 Confirmed Anthropic platform docs
Pricing is $5 / $25 per M tokens, unchanged from 4.7 Confirmed Anthropic + AWS + multiple reviewers
Fast mode is $10 / $50 per M tokens, 2.5x speed Confirmed Anthropic docs + codersera + llm-stats
SWE-bench Verified hits 88.6% (vs 87.6% on 4.7) Confirmed Artificial Analysis Intelligence Index #1
GPQA Diamond regresses slightly (93.6% vs 94.2%) Confirmed llm-stats, multiple reviewers
Dynamic Workflows runs hundreds of parallel subagents Confirmed Anthropic press materials, research preview
Migration from 4.7 is non-breaking Confirmed No API contract changes per Anthropic docs
Mythos-class models follow "in the coming weeks" Likely Anthropic announcement, no exact date
4.8 is the cost-effective default for new coding agents Likely Same price, measurably better agentic coding

Pricing: Standard, Fast Mode, Cache, Batch

Tier Input / 1M Output / 1M Note
Standard $5.00 $25.00 Same as 4.7
Fast Mode (preview) $10.00 $50.00 2.5x speed, set speed: "fast"
Cache hit $0.50 $25.00 Up to 90% input discount
Cache write (5m) $6.25 $25.00 +25% on first write
Batch API $2.50 $12.50 50% discount, async
US-only inference $5.50 $27.50 1.1x multiplier

Comparison to the cheapest frontier alternatives in 2026:

Model Input / 1M Output / 1M $10 buys (output) Source
Claude Opus 4.8 $5.00 $25.00 400K tokens Anthropic
Claude Opus 4.7 $5.00 $25.00 400K tokens Opus 4.7 review
GPT-5.5 $3.00 $15.00 666K tokens Frontier comparison
Gemini 3.5 Pro $2.50 $10.00 1M tokens Google
DeepSeek V4 $0.27 $1.10 9M tokens DeepSeek pricing

Opus 4.8 is the most expensive frontier model on the market by output rate, ~2.5x of GPT-5.5 and 22x of DeepSeek V4. Anthropic's bet: SWE-Bench Pro and GDPval-AA gains justify the premium for agentic coding workloads. Numbers below test that claim.

Benchmark Numbers: 4.8 vs 4.7 vs GPT-5.5

Every benchmark below is the headline figure from Anthropic's launch materials cross-referenced against Artificial Analysis and independent reviewers. Where Anthropic claims a number and an independent test disagrees, the table flags it.

Coding Benchmarks

Benchmark Opus 4.8 Opus 4.7 Delta GPT-5.5 Winner
SWE-bench Verified 88.6% 87.6% +1.0 ~86% Opus 4.8
SWE-bench Pro 69.2% 64.3% +4.9 58.6% Opus 4.8 (+10.6 over GPT-5.5)
Terminal-Bench 2.1 74.6% 66.1% +8.5 78.2% GPT-5.5
OSWorld-Verified 83.4% 82.3% +1.1 78.7% Opus 4.8
MCP-Atlas 82.2% 77.3% +4.9 n/a Opus 4.8

Reasoning & Knowledge

Benchmark Opus 4.8 Opus 4.7 Delta Note
GPQA Diamond 93.6% 94.2% -0.6 Slight regression
USAMO 2026 96.7% — — Anthropic-published math eval
HLE with tools 57.9% 54.7% +3.2 Humanity's Last Exam
BrowseComp (single-agent) 84.3% 79.3% +5.0 Web research
Artificial Analysis II 61 — — #1 in 149-model class

Agentic Composite

Metric Opus 4.8 GPT-5.5 Note
GDPval-AA Elo 1890 1769 +121 Elo = ~67% head-to-head
Super-Agent end-to-end 100% <100% Only model to complete every case
Code-flaw rate vs Opus 4.7 0.25x — 4x reduction per Anthropic

The GPQA regression matters less than it looks — at 93.6% the model is near-saturated on a benchmark that GPT-5.5 also clusters around 94%. The interesting shifts are agentic: +137 GDPval-AA Elo points and +4.9 SWE-Bench Pro is a generational move on workloads that actually pay for frontier pricing.

What's Actually New (Beyond Numbers)

Pulling from Anthropic's official what's-new page, four feature deltas matter for production builders:

Feature Behavior Why it matters
Mid-conversation system messages role: "system" accepted after user turns Preserves prompt cache hits — long agentic loops keep their 90% input discount when steering the model mid-session
Effort default = high Was medium on 4.7 First-call latency and cost go up by default; set effort: "medium" to keep prior behavior
Adaptive thinking only Extended thinking budgets removed Code using thinking: {type: "enabled", budget_tokens: N} returns 400; must migrate to thinking: {type: "adaptive"}
Lower cache minimum 1,024 tokens (down from prior) Previously uncacheable short system prompts now build cache entries with zero code changes

The migration impact: only the extended-thinking path is a hard break. Everything else is opt-in or backwards-compatible. Anthropic's migration guide covers the full diff.

Refusal stop details

Opus 4.8 now publicly exposes stop_details on refusal responses, with a documented category list. Applications can route refusals to the right next-step UX (compliance hand-off vs reformulation prompt) without parsing string heuristics. No beta header required.

Dynamic Workflows: The Real Story

Anthropic positioned Dynamic Workflows as the headline feature, but the reality is narrower than the marketing copy suggests.

Confirmed mechanics:

What this looks like at API cost level:

Subagent count Avg input/agent Avg output/agent Cost per workflow run
50 8K 4K $7.00
200 8K 4K $28.00
500 8K 4K $70.00
1,000 8K 4K $140.00

That cost model assumes cheaper-tier subagents (Sonnet 4.5 at $3/$15) and Opus 4.8 only as the orchestrator. Running all subagents on Opus 4.8 would 3-5x these numbers. The economics make sense when the workflow replaces multiple engineer-days; less so for casual refactors.

Likely caveats (not confirmed but consistent with prior Claude releases): hidden orchestration token overhead, cap on concurrent subagents per account, possible latency floor from the verification loop. We'll update this section as more production data lands.

Migration Cost Math: Should You Switch?

For teams already on Opus 4.7, the calculus is straightforward because pricing held flat. The question is whether the agentic gains justify the regression risk on prompts tuned for 4.7's behavior.

Token-level cost: identical at standard rate

Monthly tokens (50/50 in/out) Opus 4.7 cost Opus 4.8 cost Delta
10M $150 $150 $0
100M $1,500 $1,500 $0
1B $15,000 $15,000 $0

No premium for the upgrade. The only cost increase comes from the default effort: "high" change — same prompts that ran on 4.7 with default effort will now consume more thinking tokens. Two ways to neutralize:

  1. Set effort: "medium" explicitly to preserve 4.7's default behavior.
  2. Let effort: "high" run and rely on adaptive thinking to skip reasoning when not needed.

Option 2 is the Anthropic-recommended path; Option 1 is the safer rollout for cost-sensitive teams.

Agentic workload payback

Workload 4.7 baseline 4.8 expected Real payback
Single-pass code review Same Same Marginal — GPQA flat
Multi-step refactor Baseline -4x flaw rate High value if your QA tier catches flaws
Codebase migration (Dynamic Workflows) Manual orchestration One Opus 4.8 plan High if you have test coverage
Customer-facing agent Baseline +5pt BrowseComp Modest
Math-heavy research Baseline GPQA -0.6pt Net negative

The honest read: migrate by default for agentic coding, keep 4.7 routing for pure math/reasoning loads if your tuning is already tight there. The flaw-reduction claim is the strongest reason to flip; it scales with downstream QA cost.

Fast Mode break-even

Fast mode doubles the per-token rate to $10 / $50 but runs 2.5x faster. The break-even is workload-shape dependent:

Scenario Standard total cost Fast total cost Latency saving Worth it?
Interactive chat, 500 tokens out $0.0125 $0.025 -3s vs -1.2s Yes if user-facing
Batch evaluation, 5K tokens out $0.125 $0.25 -50s vs -20s No — use batch API at 50% off
Real-time copilot, 200 tokens out $0.005 $0.010 -1.2s vs -0.5s Yes
Long generation, 50K tokens out $1.25 $2.50 -8min vs -3min Maybe — depends on SLA

Fast mode is correctly priced for interactive workloads where wall-clock seconds map to revenue. For everything else, standard mode wins on cost.

Where Opus 4.8 Still Loses

Three places where Opus 4.8 is not the right call:

Workload Pick instead Reason
Terminal-only agentic coding GPT-5.5 78.2% vs 74.6% on Terminal-Bench 2.1
Tight-budget routing DeepSeek V4 22x cheaper output, 81% SWE-Bench Verified
Pure GPQA / scientific reasoning Opus 4.7 94.2% vs 93.6%, negligible practical diff but free

Opus 4.8 is also currently capped at 200K context on Microsoft Foundry while running 1M elsewhere. Teams on Foundry waiting for context parity should hold off or route through Bedrock / Vertex AI in the interim.

Use Case Matrix

Use Case Best Tier Why
Production coding agent with QA pipeline Opus 4.8 standard -4x flaw rate compounds with QA cost savings
Interactive code copilot Opus 4.8 Fast Mode 2.5x speed at $10/$50 is correctly priced
Cheap evaluation harness Opus 4.8 Batch API $2.50 / $12.50 with async tolerance
Codebase migration (1M+ LOC) Opus 4.8 Dynamic Workflows Currently the only production-grade option
High-volume customer-facing chat GPT-5.5 or Sonnet 4.8 Opus pricing rarely justified for chat
Long-tail Q&A on internal docs Sonnet + Opus router Use Sonnet for 95% of traffic, escalate to Opus on confidence drops
Math / reasoning specialty Opus 4.7 or DeepSeek R1 Opus 4.8 GPQA regression, R1 cheaper
Free-tier prototyping DeepSeek V4 5M free tokens Zero cost, frontier quality

Final Recommendation

For teams already deploying Claude Opus 4.7 on agentic coding workloads, migrate to 4.8 by default. The +4.9 SWE-Bench Pro and +137 GDPval-AA Elo gains arrive at the same per-token price; the only meaningful risk is the effort: high default change, neutralized by one config line.

For new builds, evaluate against GPT-5.5 on your specific workload before committing. GPT-5.5 is cheaper ($3/$15 vs $5/$25) and wins Terminal-Bench, but loses SWE-Bench Pro by 10.6 pts and GDPval-AA by 121 Elo. The decision is dominated by which benchmark family matches your workload.

For cost-constrained production, DeepSeek V4 at $0.27/$1.10 remains the value-per-quality champion. Opus 4.8 buys you ~7-10 percentage points of headroom on the hardest agentic benchmarks for 22x the per-token cost. The math only works when those points map to measurable revenue or QA cost reduction.

TokenMix routes Opus 4.8 at Anthropic's official rates with one API key across 300+ models, so swapping between Opus 4.8 / 4.7 / GPT-5.5 / DeepSeek V4 is a model-string change rather than a vendor migration.

FAQ

Is Claude Opus 4.8 worth migrating from Opus 4.7?

Yes for agentic coding, marginal for chat, no for pure math. SWE-Bench Pro climbs +4.9 pts and code-flaw rate drops 4x at the same per-token price. GPQA Diamond drops 0.6 pts, which is statistically negligible but means the math-heavy edge of Opus 4.7 survives. Migration is non-breaking at the API contract level.

What is the actual pricing for Claude Opus 4.8?

Standard: $5 per million input tokens and $25 per million output tokens — identical to Opus 4.7. Fast Mode (research preview): $10 / $50 per million. Cache hits get up to 90% input discount; batch API is 50% off; US-only inference adds a 1.1x multiplier. Source: Anthropic platform docs and AWS Bedrock launch announcement.

How does Opus 4.8 compare to GPT-5.5?

Opus 4.8 wins SWE-Bench Pro by 10.6 pts, GDPval-AA by 121 Elo, and OSWorld by 4.7 pts. GPT-5.5 wins Terminal-Bench 2.1 by 3.6 pts and costs 40% less per output token. For agentic coding pipelines with QA, Opus 4.8. For terminal automation or cost-sensitive deployments, GPT-5.5.

What is Fast Mode and when should I use it?

Fast Mode runs the same Opus 4.8 model at 2.5x the output token rate (up to 62 tokens/sec measured by Artificial Analysis) for double the per-token price. It's correctly priced for interactive user-facing workloads where wall-clock latency maps to revenue — copilots, real-time coding assistance. For batch evals or async workloads, use the standard rate or the batch API at 50% off.

Is Dynamic Workflows available now?

Yes, in research preview through Claude Code. Opus 4.8 plans the work and spins up hundreds of parallel subagent calls, self-verifying outputs against existing tests. Target workload is codebase migrations spanning 100K+ lines. Production GA timing not announced.

What changed in the API contract from Opus 4.7?

Three things require code review: (1) effort default changed from medium to high, which raises cost unless you set it explicitly; (2) extended thinking budgets are removed — thinking: {type: "enabled", budget_tokens: N} returns 400, must migrate to thinking: {type: "adaptive"}; (3) temperature, top_p, top_k still return 400 if set (unchanged from 4.7). Everything else is backward compatible.

What's the context window and output limit?

1 million tokens input context window on Claude API, AWS Bedrock, and Google Cloud Vertex AI. 200K tokens on Microsoft Foundry. Max output is 128K tokens by default, up to 300K via the output-300k-2026-03-24 beta header on the Message Batches API.

How does Opus 4.8 compare to Sonnet 4.8 on cost?

Sonnet 4.8 runs at $3 / $15 per million tokens — 40% cheaper than Opus 4.8. For chat, summarization, and general Q&A, Sonnet 4.8 covers 90%+ of workloads at the lower price. Route to Opus 4.8 only when SWE-Bench Pro, agentic coding, or long-horizon planning are the critical path.

Where can I access Claude Opus 4.8 today?

Claude API (model ID claude-opus-4-8), Claude.ai (Pro, Max, Team, Enterprise tiers), AWS Bedrock, Google Cloud Vertex AI, and Microsoft Foundry. TokenMix.ai provides Opus 4.8 access alongside 300+ other models through a single OpenAI-compatible endpoint at Anthropic's official rate.

Sources

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