Claude Opus 4.8 (Fast) vs Gemini 2.5 Flash: API Cost Comparison
Compare the API pricing, context windows, features, and real-world cost projections for Claude Opus 4.8 (Fast) (Anthropic) and Gemini 2.5 Flash (Google). Use the interactive calculator below to compute your exact monthly cost based on your token usage and request volume.
Prices verified Jun 26, 2026
Interactive Cost Calculator
Fills in typical token counts for a workload type
Tokens in each prompt sent to the model
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Total API calls per month
Showing costs for 2 models. Cheapest: Gemini 2.5 Flash at $15.50/month.
| Alert | |||||||
|---|---|---|---|---|---|---|---|
BestGemini 2.5 Flash | $15.50 | $0.001550 | $3.00 | $12.50 | 95.6% | Alerts coming soon | |
Claude Opus 4.8 (Fast) | Anthropic | $350.00 | $0.035000 | $100.00 | $250.00 | — | Alerts coming soon |
Monthly Cost Comparison
Price Comparison at a Glance
All prices are in USD per 1 million tokens ($/M tokens). Lower is cheaper.
| Pricing Type | Claude Opus 4.8 (Fast) | Gemini 2.5 Flash | Cheaper |
|---|---|---|---|
| Input (standard) | $10.00/M | $0.30/M | Gemini 2.5 Flash |
| Output | $50.00/M | $2.50/M | Gemini 2.5 Flash |
| Cached input | N/A | $0.03/M | — |
| Batch input | N/A | $0.15/M | — |
| Batch output | N/A | $1.25/M | — |
Prices last verified: 2026-03-24 – 2026-06-26
Cost Breakdown by Usage Volume
Estimated monthly costs at different request volumes, assuming 1,000 input tokens and 500 output tokens per request. Adjust in the calculator above for your specific use case.
| Volume | Claude Opus 4.8 (Fast)Monthly | Gemini 2.5 FlashMonthly | Claude Opus 4.8 (Fast)Per request | Gemini 2.5 FlashPer request |
|---|---|---|---|---|
| 1K requests/mo | $35.00 | $1.55 | $0.035000 | $0.001550 |
| 10K requests/mo | $350.00 | $15.50 | $0.035000 | $0.001550 |
| 100K requests/mo | $3,500.00 | $155.00 | $0.035000 | $0.001550 |
| 1M requests/mo | $35,000.00 | $1,550.00 | $0.035000 | $0.001550 |
Green values indicate the lower-cost option at each volume tier. Cost per request is calculated at 1,000 input + 500 output tokens using standard (non-batch, non-cached) pricing.
Price History
Input price per 1M tokensWhen to Choose Claude Opus 4.8 (Fast)
by Anthropic
- General chatbot
Input / 1M tokens
$10.00/M
Output / 1M tokens
$50.00/M
Context window
1,000,000
Tier
premium
When to Choose Gemini 2.5 Flash
by Google
- Customer support
- Data extraction
- General chatbot
Input / 1M tokens
$0.30/M
Output / 1M tokens
$2.50/M
Context window
1,048,576
Tier
mid
Key Differences Beyond Price
Cost is only one factor in choosing an AI model. Context window size, rate limits, supported features, and latency all affect whether a model fits your use case.
| Capability | Claude Opus 4.8 (Fast) | Gemini 2.5 Flash |
|---|---|---|
| Context window | 1,000,000 tokens | 1,048,576 tokens |
| Max output tokens | 128,000 tokens | 65,536 tokens |
| Performance tier | Premium | Mid |
| Vision / image input | Yes | Yes |
| Function calling | Yes | Yes |
| JSON mode | Yes | Yes |
| Prompt caching | No | Yes |
| Batch API (50% discount) | No | Yes |
| Extended reasoning | Yes | Yes |
| Fine-tuning | No | No |
| Rate limit (req/min) | Not published | 4,000 |
Gemini 2.5 Flash notes
Thinking tokens billed separately. Base non-thinking pricing shown.
Frequently Asked Questions
Is Claude Opus 4.8 (Fast) cheaper than Gemini 2.5 Flash?
At standard usage (1,000 input tokens, 500 output tokens, 100,000 requests/month), Gemini 2.5 Flash costs $155.00/month versus $3,500.00/month for Claude Opus 4.8 (Fast) — a 96% saving. Your actual savings will vary based on your token profile; output-heavy workloads amplify differences in output pricing.
Which model has a larger context window, Claude Opus 4.8 (Fast) or Gemini 2.5 Flash?
Gemini 2.5 Flash has a larger context window at 1,048,576 tokens, compared to 1,000,000 tokens for Claude Opus 4.8 (Fast). A larger context window is important for processing long documents, multi-turn conversations, or large codebases without truncation.
Do Claude Opus 4.8 (Fast) and Gemini 2.5 Flash support the Batch API?
Gemini 2.5 Flash supports the Batch API (50% discount for async processing), while Claude Opus 4.8 (Fast) does not. If your workload tolerates up to 24-hour latency, routing to Gemini 2.5 Flash with batch pricing could significantly cut costs versus Claude Opus 4.8 (Fast)'s standard rate.
Which model offers better prompt caching?
Gemini 2.5 Flash supports prompt caching at $0.03/M for cached input, while Claude Opus 4.8 (Fast) does not offer prompt caching. For RAG applications or chatbots with large, repeated context, Gemini 2.5 Flash's caching capability can substantially reduce effective costs.
What are the best use cases for Claude Opus 4.8 (Fast) vs Gemini 2.5 Flash?
Both models are well-suited for General chatbot. Claude Opus 4.8 (Fast) is particularly strong for overlapping tasks. Gemini 2.5 Flash is favored for Customer support, Data extraction. At the same quality level, the lower-cost model is usually preferable; use this page's calculator to compare total monthly spend at your volume.
What is the cost per request for Claude Opus 4.8 (Fast) vs Gemini 2.5 Flash?
At 1,000 input tokens and 500 output tokens per request — a typical conversational workload — Claude Opus 4.8 (Fast) costs $0.035000 per request and Gemini 2.5 Flash costs $0.001550 per request. At 100,000 requests/month, that translates to $3,500.00 and $155.00 respectively. Use the interactive calculator to adjust these parameters for your actual workload.
Claude Opus 4.8 (Fast) vs Gemini 2.5 Flash: Summary
When comparing Claude Opus 4.8 (Fast) and Gemini 2.5 Flash for API cost, the right choice depends on your workload's token profile, required features, and tolerance for latency. Gemini 2.5 Flash offers lower total cost at standard usage volumes (1,000 input + 500 output tokens per request at 100,000 requests/month) at $155.00/month, compared to $3,500.00/month for Claude Opus 4.8 (Fast).
Both models are priced in USD per million tokens, the standard unit across all major AI API providers. Claude Opus 4.8 (Fast) charges $10.00/M for input tokens and $50.00/M for output tokens. Gemini 2.5 Flash charges $0.30/M input and $2.50/M output. If your workload is output-heavy (more tokens generated than consumed as input), the model with the lower output price compounds cost savings significantly at scale.
Prompt caching is supported by Gemini 2.5 Flash but not Claude Opus 4.8 (Fast). For workloads with large, repeated system prompts or document context — such as RAG pipelines or multi-turn conversations with a fixed knowledge base — prompt caching can reduce effective input costs by 60–90%, which may change the cost ranking between these two models at your specific usage pattern.
Context window capacity differs between the two: Gemini 2.5 Flash supports up to 1,048,576 tokens in a single request, versus 1,000,000 tokens for Claude Opus 4.8 (Fast). A larger context window is essential for document summarization, large codebase analysis, and multi-document retrieval-augmented generation (RAG) applications.
Use the interactive calculator at the top of this page to enter your actual token usage and monthly request volume for a precise cost comparison tailored to your workload. Adjust for batch API discounts and prompt caching to find the most cost-effective option for your specific deployment.
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Relevant Use Cases
See cost recommendations for workloads where Claude Opus 4.8 (Fast) or Gemini 2.5 Flash is recommended.