API cost decision in 10 seconds

NewSolar Mini 4 vs Union Alpha

Pick Union Alpha for lower cost; pick Solar Mini 4 only if the larger context window matters more.

Page updated: 2026-09-23T11:07:57Z Data confirmed: 2026-09-23T12:07:51Z Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick Union Alpha for lower cost; pick Solar Mini 4 only if the larger context window matters more.

On the standard 1M input plus 500K output workload, Union Alpha is estimated at $0 vs $0.15 for Solar Mini 4, saving $0.15 (100% lower).

Cost-first pickUnion Alpha

Context-first pickSolar Mini 4

Sample savings$0.15100%

10x traffic gap$1.5

Solar Mini 4 has more context, but Union Alpha saves $0.15 on the standard workload. At 10x that traffic, the same price gap is about $1.5. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

Union Alpha stays cheaper across input-heavy, balanced, and output-heavy sample workloads.

Workload shape	Token mix	Better pick	Solar Mini 4	Union Alpha
Input-heavy / RAG	5M input + 500K output	Union Alpha	$0.35	$0
Balanced workload	1M input + 1M output	Union Alpha	$0.25	$0
Output-heavy chatbot	1M input + 5M output	Union Alpha	$1.05	$0

Cheaper input Union Alpha $0.05 vs $0 / 1M

Union Alpha is free for input tokens while Solar Mini 4 costs $0.05 per 1M tokens.

Cheaper output Union Alpha $0.2 vs $0 / 1M

Union Alpha is free for output tokens while Solar Mini 4 costs $0.2 per 1M tokens.

Larger context Solar Mini 4 524.29K vs 262.14K

Solar Mini 4 has 262.14K more context (2x larger).

Sample workload Union Alpha $0.15 vs $0

Union Alpha is free for the standard workload while the other model is estimated at $0.15.

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.

Monthly input tokens Monthly output tokens

Solar Mini 4 Calculating… Estimated API cost

Union Alpha Calculating… Estimated API cost

Cheaper for this workload Calculating… Difference: calculating…

This estimate uses normalized public API pricing per 1M tokens. It is a planning aid, not a billing quote. Verify provider pricing, limits, and terms before production use.

Quick Decision

Verdict

Union Alpha has the lower input price; Union Alpha has the lower output price; Solar Mini 4 offers the larger context window. For the 1M input plus 500K output sample, Union Alpha is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $0.15 for Solar Mini 4 and $0 for Union Alpha.

Best Fit

Choose Solar Mini 4 when you care most about larger context window.

Choose Union Alpha when you care most about lower input-token price, and lower output-token price.

Decision Notes

On the standard 1M input plus 500K output workload, Union Alpha is estimated at $0 vs $0.15 for Solar Mini 4, saving $0.15 (100% lower).
Union Alpha is free for the standard workload while the other model is estimated at $0.15.
Union Alpha is free for input tokens while Solar Mini 4 costs $0.05 per 1M tokens.
Union Alpha is free for output tokens while Solar Mini 4 costs $0.2 per 1M tokens.
Solar Mini 4 has 262.14K more context (2x larger).

Head-to-Head Specs

Feature	NewSolar Mini 4 (Upstage)	Union Alpha (stealth)
Input Price prompt tokens per 1M	$0.05	$0
Completion Price per 1M tokens	$0.2	$0
Sample Workload Cost 1M input + 500K output	$0.15	$0
Context Window	524.29K	262.14K
Release Date	2026-09-23	2026-09-16

Use-Case Decision Matrix

Use case	Better pick	Why
Budget-constrained production	Union Alpha	On the standard 1M input plus 500K output workload, Union Alpha is estimated at $0 vs $0.15 for Solar Mini 4, saving $0.15 (100% lower).
High-volume input processing	Union Alpha	Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbots	Union Alpha	Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document work	Solar Mini 4	A larger context window leaves more room for retrieved passages, conversation history, or source files.

Related Alternatives

Same-provider lower-cost swaps

No lower-cost same-provider swap is currently tracked for this pair.

Larger context near this budget

GPT-6 Luna Pro (batch) offers 1.05M context with $0.17 sample workload cost.
GPT-6 Luna (batch) offers 1.05M context with $0.17 sample workload cost.
Owl Alpha offers 1.05M context with $0 sample workload cost.
DeepSeek V4 Flash 0423 offers 1.05M context with $0.18 sample workload cost.

Popular competitors

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DeepSeek V4.1 Flash · DeepSeek · #3
Hy4 preview · Tencent · #4

Cheaper alternatives

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Larger context alternatives

Find models with larger context windows for RAG, long documents, and codebase review.

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Provider catalogs

Compare models within provider hubs before choosing a final API vendor.

Open provider hubs

Upstage catalog

Review all tracked Upstage models before deciding whether this matchup is the right shortlist.

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stealth catalog

Check other stealth models with comparable pricing, context, or release timing.

Open stealth models

Solar Mini 4

Solar Mini 4 is Upstage's compact, cost-efficient language model, a 35B-parameter mixture-of-experts with 3B active parameters and a 524K context window. It is built for agentic use cases where response...

Union Alpha

Union Alpha is a multimodal model built for research, coding, and agentic workflows, while delivering frontier-level performance across a broad range of general-purpose tasks. Union Alpha is a stealth model....