GPT-5.6 Terra vs Claude Fable 5
OpenAI's GPT-5.6 Terra and Anthropic's Claude Fable 5 both target production language workloads, but they price and behave differently. Here is the side-by-side.
Pricing checked against provider documentation on . How we verify
The short answer
GPT-5.6 Terra is the cheaper option — roughly 4.4x less on a blended workload, and it suits balanced production workloads. Claude Fable 5 justifies its premium when you need long-horizon agentic engineering.
OpenAI • GPT-5.6
$2.00 / $12.00
/ 1M tokens (input / output)
The everyday tier of the GPT-5.6 family, roughly corresponding to the old 'mini' slot but benchmarking above the previous generation's flagship. For most application backends this is the default worth trying before reaching for Sol, since it clears Claude Fable 5 on several evals at a fraction of the cost.
Anthropic • Claude 5
$10.00 / $50.00
/ 1M tokens (input / output)
Anthropic's most capable widely released model, built for agents that run for hours rather than seconds. Adaptive thinking is always on and cannot be disabled, which is part of why it tops the Artificial Analysis Intelligence Index — and why its cost per task runs roughly triple GPT-5.6 Sol's for a one-point intelligence lead.
Input price
Claude Fable 5 is 5.0x the price than GPT-5.6 Terra on input tokens.
Output price
Claude Fable 5 is 4.2x the price than GPT-5.6 Terra on output tokens — usually the side that dominates the bill.
Monthly cost at three workload sizes
Standard (non-batch, non-cached) rates. Reasoning models will exceed these figures because thinking tokens bill as output.
| Workload | GPT-5.6 Terra | Claude Fable 5 | Difference |
|---|---|---|---|
| Light — 1M in / 200K out | $4 | $20 | $16 |
| Moderate — 10M in / 2M out | $44 | $200 | $156 |
| Heavy — 100M in / 20M out | $440 | $2,000 | $1,560 |
Specification comparison
| Attribute | GPT-5.6 Terra | Claude Fable 5 |
|---|---|---|
| Input (/ 1M tokens) | $2.00 | $10.00 |
| Output (/ 1M tokens) | $12.00 | $50.00 |
| Cached input | $0.20 | $1.00 |
| Context window | 1,048,576 tokens | 1,000,000 tokens |
| Max output | 128,000 tokens | 128,000 tokens |
| Native reasoning | Yes | Yes |
| Knowledge cutoff | 2026-02 | 2026-01 |
| Relative latency | medium | high |
| Open weights | No | No |
| API model ID | gpt-5.6-terra | claude-fable-5 |
| Status | stable | stable |
GPT-5.6 Terra: Cut 20% from the $2.50/$15 launch price on 2026-07-30.
Claude Fable 5: 5-minute cache writes $12.50/MTok, 1-hour $20/MTok. Requires 30-day data retention, so not available under zero-data-retention terms.
Choose GPT-5.6 Terra if…
- Customer support and chat backends
- RAG and document processing pipelines
- Mid-complexity coding tasks
- Tool-calling agents at scale
Choose Claude Fable 5 if…
- Multi-hour autonomous coding runs
- Large codebase migrations
- Hard scientific workflows
- High-stakes legal and medical analysis
Frequently asked
Is GPT-5.6 Terra or Claude Fable 5 cheaper?
GPT-5.6 Terra is cheaper. On a blended 3:1 input-to-output workload it costs about 4.4x less than Claude Fable 5.
Which has the larger context window, GPT-5.6 Terra or Claude Fable 5?
GPT-5.6 Terra has the larger window at 1.05M tokens versus 1M.
Should I use GPT-5.6 Terra or Claude Fable 5?
Pick GPT-5.6 Terra for balanced production workloads. Pick Claude Fable 5 for long-horizon agentic engineering. If cost dominates the decision, GPT-5.6 Terra wins; if you need the capability ceiling, benchmark both on your own evals before committing.