Claude Opus 4.8 vs Gemini 3.5
Pricing, benchmarks, and use case comparison
Verdict
Our pick: Claude Opus 4.8Pick Claude Opus 4.8 for top-end autonomous coding and enterprise reasoning where accuracy compounds; pick Gemini 3.5 Flash when you want frontier-adjacent agent quality with much faster, cheaper output.
Specs comparison
| Claude Opus 4.8 | Gemini 3.5 | |
|---|---|---|
| Provider | Anthropic | Google DeepMind |
| Type | Closed source | Closed source |
| Context window | ✓1M | 1,048,576 tokens (Gemini 3.5 Flash; Pro variant not yet released) |
| Input / 1M tokens | $5.00 | ✓$1.50 |
| Output / 1M tokens | $25.00 | $9.00 |
| Release date | 2026-05 | 2026-05 |
Benchmarks
| Benchmark | Claude Opus 4.8 | Gemini 3.5 |
|---|---|---|
| SWE-bench Verified | 88.6% | - |
| SWE-bench Pro | 69.2% | - |
| Terminal-Bench 2.1 | 74.6% | - |
| GPQA Diamond | 93.6% | - |
| Artificial Analysis Intelligence Index | 61.4 | - |
| Terminal-Bench 2.1 (coding) | - | 76.2% |
| MCP Atlas (tool use) | - | 83.6% |
| CharXiv Reasoning (multimodal) | - | 84.2% |
Scores sourced from official provider release posts and independent benchmark aggregators.
Capability and benchmarks
Claude Opus 4.8 is the heavier reasoner: 88.6% SWE-bench Verified, 69.2% SWE-bench Pro, 74.6% Terminal-Bench 2.1, and 93.6% GPQA Diamond, with an Artificial Analysis Intelligence Index of 61.4. Gemini 3.5 Flash counters on agentic tool use and multimodal work: 83.6% on MCP Atlas (Google reports this above Opus 4.7's 79.1% and GPT-5.5's 77.8%), 76.2% Terminal-Bench 2.1, and 84.2% CharXiv chart reasoning. Opus wins deep coding and science; Gemini wins tool-calling reliability and speed (capability speed 90 vs Opus 68).
Price and context
Both offer roughly 1M-token context (Opus 1M; Gemini 3.5 Flash 1,048,576). Pricing diverges sharply: Opus 4.8 is $5 input / $25 output per 1M, while Gemini 3.5 Flash is $1.50 input / $9 output with cached input at $0.15/1M. Gemini is the clear cost-efficiency pick and generates output about 4x faster than prior Pro-tier models, which matters for agents making many calls.
Which to pick
- Pick Opus 4.8 for long-horizon autonomous engineering, high-stakes analysis, and its honesty edge (far less likely to let code flaws pass unflagged), where per-token cost is secondary to correctness.
- Pick Gemini 3.5 Flash for high-volume production agents, multimodal document and chart understanding, and workloads that were previously too costly on a Pro model.
Note Gemini 3.5 Pro was announced but had not launched as of July 2026, so today's comparison is Opus 4.8 against the Flash tier.
Which should you choose?
Choose Claude Opus 4.8 if...
- →You need top-tier autonomous coding and multi-step agentic reliability
- →You run long-horizon agent traces that previously derailed after compaction
- →You want enterprise-grade reasoning with 1M context and 128k output
- →You need throughput and are willing to pay fast-mode premium for 2.5x speed
Choose Gemini 3.5 if...
- →You need frontier agent/coding performance without frontier prices
- →Building autonomous agents that make many tool calls
- →High-throughput production workloads that were previously too costly on a Pro model
- →You want a strong default multimodal model with a 1M-token context window