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Head-to-head comparison

Apertus v1.5 8B vs Solar Pro 4

Apertus v1.5 8B (Swiss Ai) 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 18 August 2026

As of 18 August 2026, Solar Pro 4 holds the stronger ModelCap Index position (#51 vs #166).

Which should you choose?

Choose Apertus v1.5 8B if…

  • ModelCap publishes no field on which Apertus v1.5 8B leads Solar Pro 4 for this pair.

Choose Solar Pro 4 if…

  • you want the stronger overall ModelCap Index position — #51 against #166 (46.5 vs 21.4 points).
  • you want provider choice — 1 listed API providers against 0.
  • you want the more recently listed model — Solar Pro 4 was listed 10 August 2026, Apertus v1.5 8B 24 July 2026.

Apertus v1.5 8B vs Solar Pro 4: specs, pricing and context

Specification comparison of Apertus v1.5 8B and Solar Pro 4
FieldApertus v1.5 8BSwiss AiSolar Pro 4Upstage
ModelCap Index position#166#51
Index score21.446.5
EvidenceEstimatedMeasured
Input price / 1M tokensUnlisted$0.03
Output price / 1M tokensUnlisted$0.12
Context window— tokens524K tokens
Max output tokens—131K
API providers listed01
Weight accessGated accessAPI only
Input modalitiesText, ImageText
First listed24 July 202610 August 2026
PublisherSwiss AiUpstage

Evidence: global corpus prior · leave-one-anchor-out calibrated · 4 public benchmark observations across 4 boards. Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.

Benchmark scores: Apertus v1.5 8B vs Solar Pro 4

Public benchmark boards where Apertus v1.5 8B or Solar Pro 4 has a published result
BoardApertus v1.5 8BSolar Pro 4Leads
Arena codingArena (LMArena)—14501427–1473Only one result
LMArena AgentLMArena—-10.1%-12.3%–-7.9%Only one result
Artificial Analysis Intelligence IndexArtificial Analysis—41.6intelligence-indexOnly 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.

Apertus v1.5 8B vs Solar Pro 4: common questions

Is Apertus v1.5 8B better than Solar Pro 4?

Solar Pro 4 ranks higher on the ModelCap Index as of 18 August 2026: #51 against #166. 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.

Is Apertus v1.5 8B cheaper than Solar Pro 4?

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, Apertus v1.5 8B or Solar Pro 4?

Both publish a —-token context window.

Which is better for coding, Apertus v1.5 8B or Solar Pro 4?

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 Apertus v1.5 8B and Solar Pro 4 open-weight models?

Apertus v1.5 8B: Gated access. 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.

Where can I run Apertus v1.5 8B and Solar Pro 4?

ModelCap currently lists 0 API providers for Apertus v1.5 8B and 1 for Solar Pro 4, from the OpenRouter catalogue snapshot the site serves; each model page lists the providers and their prices.

How current is this Apertus v1.5 8B vs Solar Pro 4 comparison?

Every figure comes from the sealed ModelCap dataset published 18 August 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.

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