Head-to-head comparison
Solar Open2 250B (Upstage) and Solar Pro 4 (Upstage) 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 1 October 2026
As of 1 October 2026, Solar Open2 250B holds the stronger ModelCap Index position (#51 vs #119).
Evidence: publisher-corpus-prior over 231 held-out anchors (22%); launch card against 2 resolved peers on 4 rows (79%); exceeds every named peer on 4 of 4 rows; no cross-lab optimism probe available; shrunk 3.7 toward the measured corpus · 3 public benchmark observations across 3 boards. Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.
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.
Solar Open2 250B ranks higher on the ModelCap Index as of 1 October 2026: #51 against #119. 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.
At least one of the two has no listed API price on ModelCap right now, so no price comparison is made.
Both publish a —-token context window.
AA Terminal-Bench 2.1: Solar Open2 250B 44.2%, Solar Pro 4 57.3% — Solar Pro 4 leads.
Solar Open2 250B: Restricted license. Solar Pro 4: 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.
ModelCap currently lists 0 API providers for Solar Open2 250B and 1 for Solar Pro 4, from the OpenRouter catalogue snapshot the site serves; each model page lists the providers and their prices.
Every figure and ModelCap Index position comes from the same published snapshot dated 1 October 2026. Publication and page updates happen separately; use the snapshot date shown on the page.