GPT OSS 120B (Fireworks) vs Kimi K2 Instruct (Fireworks): API Cost Comparison
Compare the API pricing, context windows, features, and real-world cost projections for GPT OSS 120B (Fireworks) (Fireworks AI) and Kimi K2 Instruct (Fireworks) (Fireworks AI). 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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Total API calls per month
Showing costs for 2 models. Cheapest: GPT OSS 120B (Fireworks) at $4.50/month.
| Alert | |||||||
|---|---|---|---|---|---|---|---|
BestGPT OSS 120B (Fireworks) | Fireworks AI | $4.50 | $0.000450 | $1.50 | $3.00 | 75.7% | Alerts coming soon |
Kimi K2 Instruct (Fireworks) | Fireworks AI | $18.50 | $0.001850 | $6.00 | $12.50 | — | Alerts coming soon |
Monthly Cost Comparison
Price Comparison at a Glance
All prices are in USD per 1 million tokens ($/M tokens). Lower is cheaper.
| Pricing Type | GPT OSS 120B (Fireworks) | Kimi K2 Instruct (Fireworks) | Cheaper |
|---|---|---|---|
| Input (standard) | $0.15/M | $0.60/M | GPT OSS 120B (Fireworks) |
| Output | $0.60/M | $2.50/M | GPT OSS 120B (Fireworks) |
| Cached input | $0.08/M | $0.30/M | GPT OSS 120B (Fireworks) |
| Batch input | $0.08/M | $0.30/M | GPT OSS 120B (Fireworks) |
| Batch output | $0.30/M | $1.25/M | GPT OSS 120B (Fireworks) |
Prices last verified: 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 OSS 120B (Fireworks)Monthly | Kimi K2 Instruct (Fireworks)Monthly | GPT OSS 120B (Fireworks)Per request | Kimi K2 Instruct (Fireworks)Per request |
|---|---|---|---|---|
| 1K requests/mo | $0.45 | $1.85 | $0.000450 | $0.001850 |
| 10K requests/mo | $4.50 | $18.50 | $0.000450 | $0.001850 |
| 100K requests/mo | $45.00 | $185.00 | $0.000450 | $0.001850 |
| 1M requests/mo | $450.00 | $1,850.00 | $0.000450 | $0.001850 |
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 OSS 120B (Fireworks)
by Fireworks AI
- Code generation
- Document summarization
- RAG / Semantic search
Input / 1M tokens
$0.15/M
Output / 1M tokens
$0.60/M
Context window
131,072
Tier
mid
When to Choose Kimi K2 Instruct (Fireworks)
by Fireworks AI
- Code generation
- Document summarization
- RAG / Semantic search
Input / 1M tokens
$0.60/M
Output / 1M tokens
$2.50/M
Context window
131,072
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 OSS 120B (Fireworks) | Kimi K2 Instruct (Fireworks) |
|---|---|---|
| Context window | 131,072 tokens | 131,072 tokens |
| Max output tokens | 16,384 tokens | 16,384 tokens |
| Performance tier | Mid | Mid |
| Vision / image input | No | No |
| Function calling | Yes | Yes |
| JSON mode | Yes | Yes |
| Prompt caching | Yes | Yes |
| Batch API (50% discount) | Yes | Yes |
| Extended reasoning | No | No |
| Fine-tuning | No | No |
GPT OSS 120B (Fireworks) notes
Fireworks serverless pricing. Cached input 50% discount. Batch at 50% of serverless.
Kimi K2 Instruct (Fireworks) notes
Fireworks serverless pricing. Cached input 50% discount. Batch at 50% of serverless.
Frequently Asked Questions
Is GPT OSS 120B (Fireworks) cheaper than Kimi K2 Instruct (Fireworks)?
At standard usage (1,000 input tokens, 500 output tokens, 100,000 requests/month), GPT OSS 120B (Fireworks) costs $45.00/month versus $185.00/month for Kimi K2 Instruct (Fireworks) — a 76% 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 OSS 120B (Fireworks) or Kimi K2 Instruct (Fireworks)?
Both GPT OSS 120B (Fireworks) and Kimi K2 Instruct (Fireworks) have the same context window: 131,072 tokens.
Do GPT OSS 120B (Fireworks) and Kimi K2 Instruct (Fireworks) support the Batch API?
Yes — both GPT OSS 120B (Fireworks) and Kimi K2 Instruct (Fireworks) support batch API processing, which offers a 50% discount on input and output costs in exchange for up to 24-hour turnaround. Ideal for offline workloads like bulk document processing or nightly classification pipelines.
Which model offers better prompt caching?
Both GPT OSS 120B (Fireworks) and Kimi K2 Instruct (Fireworks) support prompt caching. GPT OSS 120B (Fireworks) caches repeated input at $0.08/M (vs $0.15/M standard), while Kimi K2 Instruct (Fireworks) caches at $0.30/M (vs $0.60/M standard). For workloads with large, repeated system prompts or document context, caching can reduce effective input costs by 60–90%.
What are the best use cases for GPT OSS 120B (Fireworks) vs Kimi K2 Instruct (Fireworks)?
Both models are well-suited for Code generation, Document summarization, RAG / Semantic search. GPT OSS 120B (Fireworks) is particularly strong for overlapping tasks. Kimi K2 Instruct (Fireworks) is favored for similar workflows. 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 OSS 120B (Fireworks) vs Kimi K2 Instruct (Fireworks)?
At 1,000 input tokens and 500 output tokens per request — a typical conversational workload — GPT OSS 120B (Fireworks) costs $0.000450 per request and Kimi K2 Instruct (Fireworks) costs $0.001850 per request. At 100,000 requests/month, that translates to $45.00 and $185.00 respectively. Use the interactive calculator to adjust these parameters for your actual workload.
GPT OSS 120B (Fireworks) vs Kimi K2 Instruct (Fireworks): Summary
When comparing GPT OSS 120B (Fireworks) and Kimi K2 Instruct (Fireworks) for API cost, the right choice depends on your workload's token profile, required features, and tolerance for latency. GPT OSS 120B (Fireworks) offers lower total cost at standard usage volumes (1,000 input + 500 output tokens per request at 100,000 requests/month) at $45.00/month, compared to $185.00/month for Kimi K2 Instruct (Fireworks).
Both models are priced in USD per million tokens, the standard unit across all major AI API providers. GPT OSS 120B (Fireworks) charges $0.15/M for input tokens and $0.60/M for output tokens. Kimi K2 Instruct (Fireworks) charges $0.60/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 both models. 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: Both models support 131,072 tokens per request. 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 OSS 120B (Fireworks) or Kimi K2 Instruct (Fireworks) is recommended.