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Model infoModelsSnapshot: 15 Oct 2026

Upstage / Solar Pro

Solar Pro 4

Upstage Solar Pro 4 for text generation and multilingual workflows. Exact version and lifecycle are recorded separately from current aliases.

Language models (LLMs)
availableClosed weightsText generation
Official documentation (opens in a new tab)Reviewed 14 Oct 2026
14 of 19 specification fields collected
Context window512K512,000 tokens
Maximum output128K128,000 tokens
Input / 1M tokens$0.30Upstage API
Output / 1M tokens$1.20USD · observed 14 Oct 2026

Specifications

Provider-documented facts. “Not collected” means we have not verified that field yet, not that the feature is unsupported.

Context / input limit
512,000 tokensSource for Context / input limit (opens in a new tab)

Provider writes 512K; displayed using decimal K. No binary-token ceiling is inferred.

Maximum input tokens
Not collected

Not verified for this exact release or deployment. No unrelated sibling specification inherited.

Maximum output
128,000 tokensSource for Maximum output (opens in a new tab)

Provider publishes 128K; decimal K display, not an independently verified binary-token count.

Parameters
Not disclosedSource for Parameters (opens in a new tab)

Provider explicitly withholds parameter count.

Architecture
Not collected

Not verified for this exact release or deployment. No unrelated sibling specification inherited.

Languages
English, Korean, and JapaneseSource for Languages (opens in a new tab)
Knowledge cutoff
Feb 2026Source for Knowledge cutoff (opens in a new tab)
Release date
2026-08-06Source for Release date (opens in a new tab)
Reasoning
SupportedSource for Reasoning (opens in a new tab)
Tool calling
SupportedSource for Tool calling (opens in a new tab)
Structured output
SupportedSource for Structured output (opens in a new tab)
Streaming
SupportedSource for Streaming (opens in a new tab)

The reasoning guide documents streamed deltas for the named model aliases.

Batch processing
Not collected

Not verified for this exact release or deployment. No unrelated sibling specification inherited.

Fine-tuning
Not collected

Not verified for this exact release or deployment. No unrelated sibling specification inherited.

Context caching
SupportedSource for Context caching (opens in a new tab)

Provider publishes a discounted cached-input price. TTL, minimum prefix and setup remain unverified.

Input modalities
TextSource for Input modalities (opens in a new tab)
Output modalities
TextSource for Output modalities (opens in a new tab)
Release identity
solar-pro4-260806; current documented alias: solar-pro4Source for Release identity (opens in a new tab)

Aliases are endpoint selectors attached to the identified version, not additional independent model records.

Supported reasoning efforts
Off by default; none/minimal disable reasoning; low, medium, high, xhigh and max enable it.Source for Supported reasoning efforts (opens in a new tab)

Visible reasoning uses message.reasoning or delta.reasoning.

Access & pricing

Prices belong to an endpoint and billing tier. A provider listing does not guarantee access for every account or region.

Upstage API

Provider source (opens in a new tab)
API model ID
solar-pro4

Moving alias maps to solar-pro4-260806 in the reviewed provider catalog.

Access
API key/account required. Private and marketplace deployments have separate access and billing.
Regions
Not collected
INPUT / 1M TOKENS$0.30
OUTPUT / 1M TOKENS$1.20

Standard direct Upstage API list rates; temporary promotions and VAT are excluded. Do not treat as a private-deployment or marketplace quote. Cached input price: $0.06 / 1M tokens (base tier).

USD · observed 14 Oct 2026 · Pricing evidence (opens in a new tab)

Data & enterprise terms

Provider states API inputs are not used for training and are not stored unless service delivery requires it and this is explicitly stated.

Read the service policy (opens in a new tab)

Upstage API

Provider source (opens in a new tab)
API model ID
solar-pro4-260806

Pinned version named by the provider alongside the moving alias.

Access
API key/account required. Private and marketplace deployments have separate access and billing.
Regions
Not collected
INPUT / 1M TOKENS$0.30
OUTPUT / 1M TOKENS$1.20

Standard direct Upstage API list rates; temporary promotions and VAT are excluded. Do not treat as a private-deployment or marketplace quote. Cached input price: $0.06 / 1M tokens (base tier).

USD · observed 14 Oct 2026 · Pricing evidence (opens in a new tab)

Data & enterprise terms

Provider states API inputs are not used for training and are not stored unless service delivery requires it and this is explicitly stated.

Read the service policy (opens in a new tab)

Caching

Caching can reuse earlier input processing. Availability, lifetime and billing depend on the endpoint. A cache hit still generates a new response.

01 / INITIAL INPUTProcess & retain

The system processes eligible input and retains reusable state.

02 / LATER REQUESTCheck available state

Reuse depends on matching input, session state and the cache policy.

03 / CACHE HITReuse & generate

Reusing state can reduce repeated work. Any charges follow the billing rules below.

Upstage API

solar-pro4
Documented

The provider publishes an exact-model cached-input rate.

Support evidence (opens in a new tab)
How it works
Not collected

No verified exact-model cache contract for this field. Missing documentation does not establish lack of support.

Minimum reusable input
Not collected

No verified exact-model cache contract for this field. Missing documentation does not establish lack of support.

Lifetime & refresh
Not collected

No verified exact-model cache contract for this field. Missing documentation does not establish lack of support.

How to enable it
Not collected

No verified exact-model cache contract for this field. Missing documentation does not establish lack of support.

Usage fields
Not collected

No verified exact-model cache contract for this field. Missing documentation does not establish lack of support.

Billing rules
USD 0.06 per million cached input tokens at the standard list rate.Source for Billing rules (opens in a new tab)

Promotions and deployment-specific contracts are separate.

Limits & data boundaries
Not collected

No verified exact-model cache contract for this field. Missing documentation does not establish lack of support.

Cache reads, writes & storage
ChargeApplies toRate / unit
Cache read1Text tokens · Base tier$0.06 / 1M tokensPricing evidence (opens in a new tab)

Rate conditions

  1. Standard direct Upstage API list rates; temporary promotions and VAT are excluded. Do not treat as a private-deployment or marketplace quote.

Observed 14 Oct 2026. Write rates and storage fees are different charges; use the billing rules above.

Caching reviewed 14 Oct 2026

Upstage API

solar-pro4-260806
Documented

The provider publishes an exact-model cached-input rate.

Support evidence (opens in a new tab)
How it works
Not collected

No verified exact-model cache contract for this field. Missing documentation does not establish lack of support.

Minimum reusable input
Not collected

No verified exact-model cache contract for this field. Missing documentation does not establish lack of support.

Lifetime & refresh
Not collected

No verified exact-model cache contract for this field. Missing documentation does not establish lack of support.

How to enable it
Not collected

No verified exact-model cache contract for this field. Missing documentation does not establish lack of support.

Usage fields
Not collected

No verified exact-model cache contract for this field. Missing documentation does not establish lack of support.

Billing rules
USD 0.06 per million cached input tokens at the standard list rate.Source for Billing rules (opens in a new tab)

Promotions and deployment-specific contracts are separate.

Limits & data boundaries
Not collected

No verified exact-model cache contract for this field. Missing documentation does not establish lack of support.

Cache reads, writes & storage
ChargeApplies toRate / unit
Cache read1Text tokens · Base tier$0.06 / 1M tokensPricing evidence (opens in a new tab)

Rate conditions

  1. Standard direct Upstage API list rates; temporary promotions and VAT are excluded. Do not treat as a private-deployment or marketplace quote.

Observed 14 Oct 2026. Write rates and storage fees are different charges; use the billing rules above.

Caching reviewed 14 Oct 2026

What the measurements say

Terminal-Bench v2.1

Upstage · vendor-reported
57score as reported

Vendor release result. Full harness and inference budget have not been collected. Do not compare to other benchmark versions.

Evaluation source (opens in a new tab)

AA-LCR

Upstage · vendor-reported
71score as reported

Long-document evaluation cited by the vendor. Independent result and evaluation settings require a separate review.

Evaluation source (opens in a new tab)

Latency and throughput depend on the host, request size, reasoning settings and load. There is no measured speed or global usage figure in this record.

The record behind the model

Why it is included

Provider explicitly describes Solar Pro 4 as its closed commercial flagship. Public Solar Open weights and tokenizer repositories are separate artifacts.

Classification evidence (opens in a new tab)

Lifecycle dates

Provider-listed version release6 Aug 2026Source (opens in a new tab)

Sources reviewed