Kimi K3 vs Claude Fable 5.1 cost.
An open-weight model priced against a frontier proprietary one, on a task class where both are credible.
- Input gap
- 3.3×
- Output gap
- 3.3×
- Cached gap
- 1.2×
- Rates verified
- 2026-10-02
Current-model note: Both models are current. Kimi K3 is served under the Kimi K3 licence; rates carry their verification date.
| Current model | Input / 1M | Cached / 1M | Cache write / 1M | Output / 1M | Context |
|---|---|---|---|---|---|
| Kimi K3Official pricing ↗ | $3.00 | $0.30 | — | $15.00 | 1,048,576 |
| Claude Fable 5.1Official pricing ↗ | $10.00 | $0.25 | $12.50 | $50.00 | 1,000,000 |
Rates verified 2026-10-02. The browser may refresh them from the live catalogue. Provider pricing and tiers remain authoritative.
Kimi K3: Provider-Calibrated UTF-8 Projection
Claude Fable 5.1: Provider-Calibrated UTF-8 Projection
PDF, DOCX, code, text, and data files are extracted locally and applied to both models.
Kimi K3: unavailable
Claude Fable 5.1: documented formula
Prompt text, document contents, and image pixels stay in the browser.
Text, code, PDF, DOCX, images, audio, or video · 12 MB per file
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Workload & Scaling Planner +
What five real workloads actually cost
Headline per-token prices rarely decide a bill. Request shape does. These figures are calculated from the verified rates for Kimi K3 and Claude Fable 5.1, including any long-context tier that applies once a request crosses its threshold.
| Workload | Input | Output | Kimi K3 | Claude Fable 5.1 | Difference |
|---|---|---|---|---|---|
| Short chat turn A typical assistant exchange. | 1,000 | 500 | $0.010 | $0.035 | 3.33x cheaper on Kimi K3 |
| RAG answer Five retrieved chunks plus a question. | 12,000 | 800 | $0.048 | $0.160 | 3.33x cheaper on Kimi K3 |
| Code review A medium pull request with surrounding files. | 60,000 | 2,000 | $0.210 | $0.700 | 3.33x cheaper on Kimi K3 |
| Whole-document analysis A long report or contract read in one call. | 300,000 | 4,000 | $0.960 | $3.20 | 3.33x cheaper on Kimi K3 |
| Full-context load Filling most of a one-million-token window. | 900,000 | 4,000 | $2.76 | $9.20 | 3.33x cheaper on Kimi K3 |
"(tier)" marks a request that crossed a long-context threshold, so it is billed above the headline rate. Output length is the assumption most worth changing for your own case: paste a real prompt into the calculator above to replace these with your numbers.
The cached-input rate is the number most comparisons miss
Agents, chat threads and RAG pipelines resend the same system prompt and context on every call. Those repeated tokens bill at the cached rate, not the headline rate, so a model can be cheaper on paper and more expensive in production.
| Model | Fresh input / 1M | Cached input / 1M | Discount | Break-even |
|---|---|---|---|---|
| Kimi K3 | $3.00 | $0.300 | 90% | 1 read |
| Claude Fable 5.1 | $10.00 | $0.250 | 98% | 1 read |
Break-even assumes a cache write costs about 1.25x the base input rate, which is what OpenAI and Anthropic currently document for a short time-to-live. It answers one question: how many times a cached prefix must be re-read before caching is cheaper than paying full price each call. Above that count, every further read saves the discount shown.
A frontier-class comparison at a third of the price
Kimi K3 launched at $3 per million input tokens and $15 per million output, against $10 and $50 for Claude Fable 5.1. That is a consistent three-fold-plus gap on both sides of the bill, which is unusual: most cheaper models save on input and give some of it back on output.
Both carry very large context windows, so neither forces you into retrieval for a long document. The computed table below shows what that costs in practice at each request size.
Where an open-weight model changes the architecture
A three-fold price gap does not usually change how a system is built. What changes it is the option to self-host. An open-weight licence means you can run the model on your own hardware, which moves cost from per-token to per-hour and removes the per-request network boundary entirely.
That trade only pays above a utilisation threshold. Below it, a hosted API is cheaper and far less work. The cost lab on this site models the self-hosting crossover if you want to size it.
For confidential prompts the calculation is different again: self-hosting removes the question of what leaves your network, which for some workloads outweighs the token price entirely.
Counting is estimated on both sides here
Neither model ships a browser-runnable tokenizer, so both counts on this page are deterministic byte-length projections rather than exact counts. The comparison between them remains fair, because the same method is applied to both.
Use the provider's reported usage to reconcile an invoice. Use this page to choose between them.
Model the workload, not the marketing price.
The saving is large and consistent. The question is whether Kimi K3 holds quality on your task, and whether serving and support terms suit you.
Review calculation methodology →Measure against the model you use
Other comparisons worth running
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Frequently asked questions
How much cheaper is Kimi K3 than Claude Fable 5.1?+
Kimi K3 launched at $3 per million input and $15 per million output, against $10 and $50 for Claude Fable 5.1. That is more than three times cheaper on both input and output, which is unusual for a cheaper model.
Is Kimi K3 open source?+
It is open-weight, served under the Kimi K3 licence rather than a standard open-source licence. The practical benefit is that self-hosting is possible, which changes cost from per-token to per-hour and removes the network boundary for confidential inputs.
Are the token counts on this page exact?+
No. Neither model publishes a tokenizer that runs in a browser, so both are measured with the same deterministic byte-length projection and labelled as estimates. The comparison between them is fair because the method is identical on both sides.