text model comparison
Claude Opus 5 vs Gemini 3.8 Flash
Claude Opus 5 and Gemini 3.8 Flash are both current text models, from Anthropic and Google. Gemini 3.8 Flash is 85% cheaper per 1M input tokens than Claude Opus 5, $0.75 vs $5. On Arena Text, Claude Opus 5 scores 1490 Elo and Gemini 3.8 Flash 1497 Elo (Arena, measured October 8, 2026). Both accept about 1.05M tokens of context (1,048,576 and 1,000,000).
Data verified October 12, 2026 · Dataset 2026-10-12
Side by side
Standard-tier prices in effect today. The better value in each row is highlighted.
| Fact | Claude Opus 5 | Gemini 3.8 Flash |
|---|---|---|
| Price per 1M input tokens | $5 | $0.75 (better) |
| Price per 1M output tokens | $25 | $3.75 (better) |
| Cost of 10M input and 2M output tokens | $100 | $15 (better) |
| Arena Text | 1490 Elo (#6 of 39) | 1497 Elo (#4 of 39) (better) |
| GPQA Diamond | 93.9% (#10 of 37) | 95.4% (#3 of 37) (better) |
| FrontierMath Tiers 1-3 (v2) | 85.6% (#10 of 37) (better) | 68.4% (#21 of 37) |
| SimpleQA Verified | 59.9% (#15 of 34) | 69.7% (#7 of 34) (better) |
| Provider | Anthropic | |
| Release date | July 24, 2026 | September 2, 2026 |
| Access | API only | API only |
| Context window | 1,000,000 tokens | 1,048,576 tokens |
| Max output | 128,000 tokens | 65,536 tokens |
| Input | text, image | text, image, audio, video |
| Output | text | text |
When to choose each
Claude Opus 5
Best for
- Complex agentic coding and enterprise work as the general-purpose default before reaching for Fable 5.1
- Latency-sensitive work that can justify Fast mode pricing
Watch out for
- Fast mode pricing applies to the whole request, including above 200K input tokens, so it doubles the effective rate rather than adding a surcharge
- Cache reads are $0.50 per million (the standard 0.1x), five times Fable 5.1’s $0.25, even though Opus 5 is the cheaper model on base tokens. A cache-heavy agent loop can invert the expected cost ordering between the two.
Gemini 3.8 Flash
Best for
- High-volume agentic and coding workloads where per-token cost dominates the decision
- Multimodal pipelines that need audio, video and PDF input in one model
Watch out for
- The listed price is promotional and ends 31 December 2026; on 1 January 2027 input and output both double, to $1.50 and $7.50, and cached input goes from $0.075 to $0.15
- Output pricing is billed inclusive of thinking tokens, so reasoning-heavy prompts cost more than the output length suggests
- Google’s published comparisons are against its own previous Flash release and were not independently reproduced here
Claude Opus 5 vs Gemini 3.8 Flash FAQ
Which is cheaper, Claude Opus 5 or Gemini 3.8 Flash?
Gemini 3.8 Flash is 85% cheaper per 1M input tokens than Claude Opus 5, $0.75 vs $5. For 10M input and 2M output tokens, Claude Opus 5 costs $100 and Gemini 3.8 Flash $15 at standard rates.
Which scores higher on independent benchmarks, Claude Opus 5 or Gemini 3.8 Flash?
Gemini 3.8 Flash leads on Arena Text, 1497 Elo to 1490 Elo; Gemini 3.8 Flash leads on GPQA Diamond, 95.4% to 93.9%; Claude Opus 5 leads on FrontierMath Tiers 1-3 (v2), 85.6% to 68.4%. Scores are independent evaluations, not either vendor's launch figures.
Which has the larger context window, Claude Opus 5 or Gemini 3.8 Flash?
Both accept about 1.05M tokens of context (1,048,576 and 1,000,000).
Related comparisons
- Claude Opus 4.8 vs Claude Opus 5
- Claude Opus 4.8 vs Gemini 3.8 Flash
- Claude Opus 5.5 vs Gemini 3.8 Flash
- Claude Opus 5 vs Claude Opus 5.5
- Claude Opus 5 vs GPT-5.5
- Claude Opus 5 vs GPT-5.6 Sol
- Claude Opus 5 vs Kimi K3
- Claude Sonnet 5.5 vs Gemini 3.8 Flash
- DeepSeek-V4.1-Flash vs Gemini 3.8 Flash
- Gemini 3.6 Flash vs Gemini 3.8 Flash
Production evaluation
Choosing between Claude Opus 5 and Gemini 3.8 Flash?
Public benchmarks narrow the shortlist. We run both on your own tasks, data and cost limits, then build the routing and review controls to run the winner in production.
- A head-to-head evaluation on your real workload
- Routing between models by cost and difficulty