Skip to content
ModelCap

Head-to-head comparison

K2 Horizon 375B A23B vs GPT-5.6 Sol

K2 Horizon 375B A23B (IFM) and GPT-5.6 Sol (OpenAI) compared on the ModelCap Index, API price, context window, provider availability, weight access and every public benchmark board they share. Figures are the same ones shown on the live rankings; nothing here is a hidden score.

Snapshot as of 13 September 2026

As of 13 September 2026, GPT-5.6 Sol holds the stronger ModelCap Index position (#5 vs #30); and K2 Horizon 375B A23B ships open weights.

Which should you choose?

Choose K2 Horizon 375B A23B if…

  • you want to self-host: K2 Horizon 375B A23B ships open weights while GPT-5.6 Sol is api only.
  • you want the more recently listed model — K2 Horizon 375B A23B was listed 1 September 2026, GPT-5.6 Sol 9 July 2026.

Choose GPT-5.6 Sol if…

  • you want the stronger overall ModelCap Index position — #5 against #30 (82.2 vs 67.3 points).
  • you want provider choice — 3 listed API providers against 0.

K2 Horizon 375B A23B vs GPT-5.6 Sol: specs, pricing and context

Specification comparison of K2 Horizon 375B A23B and GPT-5.6 Sol
FieldK2 Horizon 375B A23BIFMGPT-5.6 SolOpenAI
ModelCap Index position#30#5
Index score67.382.2
EvidenceEstimatedMeasured
Input price / 1M tokensUnlisted$2.00
Output price / 1M tokensUnlisted$10.00
Context window— tokens1M tokens
Max output tokens—128K
API providers listed03
Weight accessOpen weightsAPI only
Input modalitiesTextFile, Image, Text
First listed1 September 20269 July 2026
PublisherIFMOpenAI

Evidence: global-corpus-prior over 186 held-out anchors (21%); launch card against 6 resolved peers on 11 rows (79%); optimism haircut 0 from cross-lab-probe; shrunk 4.1 toward the measured corpus · 7 public benchmark observations across 7 boards. Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.

Benchmark scores: K2 Horizon 375B A23B vs GPT-5.6 Sol

Public benchmark boards where K2 Horizon 375B A23B or GPT-5.6 Sol has a published result
BoardK2 Horizon 375B A23BGPT-5.6 SolLeads
Arena codingArena (LMArena)—15271519–1534X-HighOnly one result
LMArena AgentLMArena—7.5%6.1%–8.9%X-HighOnly one result
ARC-AGI-2ARC Prize Foundation—92.5%MaxOnly one result
ARC-AGI-3ARC Prize Foundation—7.8%MaxOnly one result
AA Intelligence IndexArtificial Analysis—47.1intelligence-index:v4.3:maxOnly one result
AA Terminal-Bench 2.1Artificial Analysis—88.0%terminal-bench:2.1:terminus-2:e2b:pass-at-1:3-repeats:source-model="GPT-5.6 Sol (max)":reasoning=trueOnly one result
AA τ²-Bench TelecomArtificial Analysis—85.1%tau2:telecom:dual-control:pass-at-1:3-repeats:source-model="GPT-5.6 Sol (max)":reasoning=trueOnly one result
AA Humanity's Last ExamArtificial Analysis—49.5%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="GPT-5.6 Sol (max)":reasoning=trueOnly one result
Terminal-Bench 4.0Terminal-Bench (Laude Institute)—37.3%33.5%–41.1%Codex · MaxOnly one result
WildClawBench OpenClawWildClawBench—67.2Only one result

Scores are the sources' own published figures for each model's best evaluated configuration; ModelCap never re-runs a benchmark.

Want a different pairing? Open the interactive comparison tool to swap either model for any current ranked language model.

K2 Horizon 375B A23B vs GPT-5.6 Sol: common questions

Is K2 Horizon 375B A23B better than GPT-5.6 Sol?

GPT-5.6 Sol ranks higher on the ModelCap Index as of 13 September 2026: #5 against #30. That is a capability ranking built from public benchmark evidence with published uncertainty; whether it is "better" for you also depends on price, context and where you can run it. Their published uncertainty intervals overlap, so the rank difference alone does not establish a reliable capability advantage for your workload.

Is K2 Horizon 375B A23B cheaper than GPT-5.6 Sol?

At least one of the two has no listed API price on ModelCap right now, so no price comparison is made.

Which has the bigger context window, K2 Horizon 375B A23B or GPT-5.6 Sol?

Both publish a —-token context window.

Which is better for coding, K2 Horizon 375B A23B or GPT-5.6 Sol?

The two models do not share a coding benchmark board on ModelCap yet, so no head-to-head coding score is published; the ModelCap Index position is the closest overall signal.

Are K2 Horizon 375B A23B and GPT-5.6 Sol open-weight models?

K2 Horizon 375B A23B: Open weights. GPT-5.6 Sol: API only. Open weights mean the checkpoint can be downloaded and self-hosted under its licence; API-only models are available solely through hosted endpoints.

Where can I run K2 Horizon 375B A23B and GPT-5.6 Sol?

ModelCap currently lists 0 API providers for K2 Horizon 375B A23B and 3 for GPT-5.6 Sol, from the OpenRouter catalogue snapshot the site serves; each model page lists the providers and their prices.

How current is this K2 Horizon 375B A23B vs GPT-5.6 Sol comparison?

Every figure comes from the sealed ModelCap dataset published 13 September 2026; the page re-renders within a minute of each data refresh, and the ModelCap Index positions are the same ones shown on the live rankings.

Explore further