openai

GPT-5.1

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CAPABILITY & COST

What else is worth comparing?

GPT-5.1149.8ECI pointsEpoch Capabilities Index · 2026-10-24
$3.751M input + 250k output tokens
ECI interval 148.4–151.7 · estimates can overlap
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This modelSelected alternativesOther dots: models with both score and price
Compare specifications for this selection

ECI points are estimates, not percentages. Overlapping intervals do not establish a winner. Nearby score does not mean equivalent capability.

INDEPENDENT EVALUATIONS

Results in context

Where does it sit?

Five nearest ECI estimates · current snapshot, not release-time scores.

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Overlapping intervals do not establish a clear winner. ECI combines source-selected benchmarks; points are not percentages. Snapshot 2026-10-24.

Test by test

No approved benchmark evaluation is linked to this exact model ID. Another version’s score is not substituted.

Each row is a different test, not a common difficulty scale. “Max” does not mean equal compute across providers.

What changes your bill?

Illustrative token baskets, not measured tasks.

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Short exchange1K input + 250 output tokens$0.0038
Long answer4K input + 4K output tokens$0.045
Document analysis100K input + 2K output tokens$0.145
Repeated workload1M input + 250K output tokens$3.75

List prices, captured 2026-10-25. Excludes caching, batch discounts, tools and retries. Token baskets are not estimates of a specific task’s token use.

Within the same developer

Five lowest listed workload costs, plus this model.

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Fixed basket: 1M input + 250k output. Logarithmic positions; labels show actual USD. Lower cost does not imply equivalent capability.

PUBLISHED LIMITS

Room to read
Room to respond

Context and maximum output are separate limits, not a quality score. They are not added together.

Context window400Ktokens
Maximum output128Ktokens

Published specifications

Context window400Ktokens
API input price$1.25USD / million tokens
API output price$10USD / million tokens
Maximum output128Kmaximum tokens per response
Output modalitiestextpublished output types
Supported parameters11API parameters listed

Model information

Provider
openai
Input modalities
image, text, file
Output modalities
text
Maximum output
128,000 tokens
Supported parameters
include_reasoning, max_completion_tokens, max_tokens, reasoning, reasoning_effort, response_format, seed, structured_outputs, tool_choice, tools, verbosity
Added to catalogue
2025-11-13
Knowledge cutoff
Not available
Catalogue snapshot
2026-10-25

Prices are per million tokens. The workload estimate uses 1,000 input and 250 output tokens. Context describes request capacity, not model quality.

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