API cost decision in 10 seconds

NewMercury 3 vs Solar Pro 4

Pick Solar Pro 4 for lower cost; pick Mercury 3 only if the larger context window matters more.

Page updated: 2026-10-19T17:07:53Z Data confirmed: 2026-10-19T18:07:54Z Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick Solar Pro 4 for lower cost; pick Mercury 3 only if the larger context window matters more.

On the standard 1M input plus 500K output workload, Solar Pro 4 is estimated at $0.27 vs $0.28 for Mercury 3, saving $0.005 (1.8% lower).

Cost-first pickSolar Pro 4

Context-first pickMercury 3

Sample savings$0.0051.8%

10x traffic gap$0.05

Mercury 3 has more context, but Solar Pro 4 saves $0.005 on the standard workload. At 10x that traffic, the same price gap is about $0.05. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

Cost winner changes by workload shape: input-heavy / RAG favors Solar Pro 4, balanced workload favors Tie, and output-heavy chatbot favors Mercury 3.

Workload shape	Token mix	Better pick	Mercury 3	Solar Pro 4
Input-heavy / RAG	5M input + 500K output	Solar Pro 4	$0.68	$0.63
Balanced workload	1M input + 1M output	Tie	$0.45	$0.45
Output-heavy chatbot	1M input + 5M output	Mercury 3	$1.85	$1.89

Cheaper input Solar Pro 4 $0.1 vs $0.09 / 1M

Solar Pro 4 is $0.01 cheaper per 1M input tokens (10% lower; 1.11x difference).

Cheaper output Mercury 3 $0.35 vs $0.36 / 1M

Mercury 3 is $0.01 cheaper per 1M output tokens (2.8% lower; 1.03x difference).

Larger context Mercury 3 1M vs 524.29K

Mercury 3 has 475.71K more context (1.91x larger).

Sample workload Solar Pro 4 $0.28 vs $0.27

Solar Pro 4 is $0.005 cheaper on the standard workload (1.8% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.

Monthly input tokens Monthly output tokens

Mercury 3 Calculating… Estimated API cost

Solar Pro 4 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

Solar Pro 4 has the lower input price; Mercury 3 has the lower output price; Mercury 3 offers the larger context window. For the 1M input plus 500K output sample, Solar Pro 4 is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $0.28 for Mercury 3 and $0.27 for Solar Pro 4.

Best Fit

Choose Mercury 3 when you care most about lower output-token price, and larger context window.

Choose Solar Pro 4 when you care most about lower input-token price.

Decision Notes

On the standard 1M input plus 500K output workload, Solar Pro 4 is estimated at $0.27 vs $0.28 for Mercury 3, saving $0.005 (1.8% lower).
Solar Pro 4 is $0.005 cheaper on the standard workload (1.8% lower).
Solar Pro 4 is $0.01 cheaper per 1M input tokens (10% lower; 1.11x difference).
Mercury 3 is $0.01 cheaper per 1M output tokens (2.8% lower; 1.03x difference).
Mercury 3 has 475.71K more context (1.91x larger).

Head-to-Head Specs

Feature	NewMercury 3 (Inception)	Solar Pro 4 (Upstage)
Input Price prompt tokens per 1M	$0.1	$0.09
Completion Price per 1M tokens	$0.35	$0.36
Sample Workload Cost 1M input + 500K output	$0.28	$0.27
Context Window	1M	524.29K
Release Date	2026-10-16	2026-08-10

Use-Case Decision Matrix

Use case	Better pick	Why
Budget-constrained production	Solar Pro 4	On the standard 1M input plus 500K output workload, Solar Pro 4 is estimated at $0.27 vs $0.28 for Mercury 3, saving $0.005 (1.8% lower).
High-volume input processing	Solar Pro 4	Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbots	Mercury 3	Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document work	Mercury 3	A larger context window leaves more room for retrieved passages, conversation history, or source files.

Related Alternatives

Same-provider lower-cost swaps

Mercury 2.5 can replace Mercury 3 when lower sample workload cost matters most: $0.11.
Solar Mini 4 can replace Solar Pro 4 when lower sample workload cost matters most: $0.15.

Larger context near this budget

Llama 4 Scout offers 1.31M context with $0.25 sample workload cost.
MiMo-V2.6-Flash offers 1.05M context with $0.28 sample workload cost.
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.

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Cheaper alternatives

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Larger context alternatives

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Provider catalogs

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Inception catalog

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Upstage catalog

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

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Mercury 3

Mercury 3 is a diffusion-based language model from Inception, and the lab's most capable model to date. It is suited for agentic workflows and real-time applications where latency compounds, such...

Solar Pro 4

Solar Pro 4 is Upstage's cost-efficient large language model, featuring a 524K context window. It is built for long-horizon tasks and agentic workflows, with strong capabilities in office productivity, document-intensive...