GPT-5.1 vs Qwen3.5 Plus (OpenRouter): API Cost Comparison
Compare the API pricing, context windows, features, and real-world cost projections for GPT-5.1 (OpenAI) and Qwen3.5 Plus (OpenRouter) (OpenRouter). Use the interactive calculator below to compute your exact monthly cost based on your token usage and request volume.
Prices verified Mar 10, 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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Showing costs for 2 models. Cheapest: Qwen3.5 Plus (OpenRouter) at $10.40/month.
| Alert | |||||||
|---|---|---|---|---|---|---|---|
BestQwen3.5 Plus (OpenRouter) | OpenRouter | $10.40 | $0.001040 | $2.60 | $7.80 | 83.4% | Alerts coming soon |
GPT-5.1 | OpenAI | $62.50 | $0.006250 | $12.50 | $50.00 | — | Alerts coming soon |
Monthly Cost Comparison
Price Comparison at a Glance
All prices are in USD per 1 million tokens ($/M tokens). Lower is cheaper.
| Pricing Type | GPT-5.1 | Qwen3.5 Plus (OpenRouter) | Cheaper |
|---|---|---|---|
| Input (standard) | $1.25/M | $0.26/M | Qwen3.5 Plus (OpenRouter) |
| Output | $10.00/M | $1.56/M | Qwen3.5 Plus (OpenRouter) |
| Cached input | $0.13/M | N/A | — |
Prices last verified: 2026-03-06 – 2026-03-10
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 | GPT-5.1Monthly | Qwen3.5 Plus (OpenRouter)Monthly | GPT-5.1Per request | Qwen3.5 Plus (OpenRouter)Per request |
|---|---|---|---|---|
| 1K requests/mo | $6.25 | $1.04 | $0.006250 | $0.001040 |
| 10K requests/mo | $62.50 | $10.40 | $0.006250 | $0.001040 |
| 100K requests/mo | $625.00 | $104.00 | $0.006250 | $0.001040 |
| 1M requests/mo | $6,250.00 | $1,040.00 | $0.006250 | $0.001040 |
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 GPT-5.1
by OpenAI
- Code generation
- Content & copywriting
- RAG / Semantic search
Input / 1M tokens
$1.25/M
Output / 1M tokens
$10.00/M
Context window
400,000
Tier
premium
When to Choose Qwen3.5 Plus (OpenRouter)
by OpenRouter
- Code generation
- Document summarization
- General chatbot
Input / 1M tokens
$0.26/M
Output / 1M tokens
$1.56/M
Context window
1,000,000
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 | GPT-5.1 | Qwen3.5 Plus (OpenRouter) |
|---|---|---|
| Context window | 400,000 tokens | 1,000,000 tokens |
| Max output tokens | 128,000 tokens | 65,536 tokens |
| Performance tier | Premium | Mid |
| Vision / image input | Yes | No |
| Function calling | Yes | Yes |
| JSON mode | Yes | Yes |
| Prompt caching | Yes | No |
| Batch API (50% discount) | No | No |
| Extended reasoning | No | No |
| Fine-tuning | No | No |
| Rate limit (req/min) | 10,000 | Not published |
GPT-5.1 notes
1M context window. Strong all-around performance between GPT-5.2 and GPT-5.
Qwen3.5 Plus (OpenRouter) notes
OpenRouter offers 200+ models — showing top 15 unique models not available from other listed providers. Prices include OpenRouter markup.
Frequently Asked Questions
Is GPT-5.1 cheaper than Qwen3.5 Plus (OpenRouter)?
At standard usage (1,000 input tokens, 500 output tokens, 100,000 requests/month), Qwen3.5 Plus (OpenRouter) costs $104.00/month versus $625.00/month for GPT-5.1 — a 83% 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, GPT-5.1 or Qwen3.5 Plus (OpenRouter)?
Qwen3.5 Plus (OpenRouter) has a larger context window at 1,000,000 tokens, compared to 400,000 tokens for GPT-5.1. A larger context window is important for processing long documents, multi-turn conversations, or large codebases without truncation.
Do GPT-5.1 and Qwen3.5 Plus (OpenRouter) support the Batch API?
Neither GPT-5.1 nor Qwen3.5 Plus (OpenRouter) currently supports a batch API with discounted pricing. For batch-eligible alternatives, consider models from OpenAI, Anthropic, or Google that include batch API support.
Which model offers better prompt caching?
GPT-5.1 supports prompt caching at $0.13/M for cached input, while Qwen3.5 Plus (OpenRouter) does not offer prompt caching. For RAG applications or chatbots with large, repeated context, GPT-5.1's caching capability can substantially reduce effective costs.
What are the best use cases for GPT-5.1 vs Qwen3.5 Plus (OpenRouter)?
Both models are well-suited for Code generation. GPT-5.1 is particularly strong for Content & copywriting, RAG / Semantic search. Qwen3.5 Plus (OpenRouter) is favored for Document summarization, General chatbot. 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 GPT-5.1 vs Qwen3.5 Plus (OpenRouter)?
At 1,000 input tokens and 500 output tokens per request — a typical conversational workload — GPT-5.1 costs $0.006250 per request and Qwen3.5 Plus (OpenRouter) costs $0.001040 per request. At 100,000 requests/month, that translates to $625.00 and $104.00 respectively. Use the interactive calculator to adjust these parameters for your actual workload.
GPT-5.1 vs Qwen3.5 Plus (OpenRouter): Summary
When comparing GPT-5.1 and Qwen3.5 Plus (OpenRouter) for API cost, the right choice depends on your workload's token profile, required features, and tolerance for latency. Qwen3.5 Plus (OpenRouter) offers lower total cost at standard usage volumes (1,000 input + 500 output tokens per request at 100,000 requests/month) at $104.00/month, compared to $625.00/month for GPT-5.1.
Both models are priced in USD per million tokens, the standard unit across all major AI API providers. GPT-5.1 charges $1.25/M for input tokens and $10.00/M for output tokens. Qwen3.5 Plus (OpenRouter) charges $0.26/M input and $1.56/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 GPT-5.1 but not Qwen3.5 Plus (OpenRouter). 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: Qwen3.5 Plus (OpenRouter) supports up to 1,000,000 tokens in a single request, versus 400,000 tokens for GPT-5.1. 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 GPT-5.1 or Qwen3.5 Plus (OpenRouter) is recommended.