API cost decision in 10 seconds

NewStep 3.7 Flash vs Mercury 2

Pick Mercury 2 for lower cost; pick Step 3.7 Flash only if the larger context window matters more.

Page updated: 2026-05-29T00:07:14Z Data confirmed: 2026-05-30T18:07:59Z Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick Mercury 2 for lower cost; pick Step 3.7 Flash only if the larger context window matters more.

On the standard 1M input plus 500K output workload, Mercury 2 is estimated at $0.62 vs $0.77 for Step 3.7 Flash, saving $0.15 (19.4% lower).

Cost-first pickMercury 2

Context-first pickStep 3.7 Flash

Sample savings$0.1519.4%

10x traffic gap$1.5

Step 3.7 Flash has more context, but Mercury 2 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.

Cost winner changes by workload shape: input-heavy / RAG favors Step 3.7 Flash, balanced workload favors Mercury 2, and output-heavy chatbot favors Mercury 2.

Workload shape	Token mix	Better pick	Step 3.7 Flash	Mercury 2
Input-heavy / RAG	5M input + 500K output	Step 3.7 Flash	$1.57	$1.62
Balanced workload	1M input + 1M output	Mercury 2	$1.35	$1
Output-heavy chatbot	1M input + 5M output	Mercury 2	$5.95	$4

Cheaper input Step 3.7 Flash $0.2 vs $0.25 / 1M

Step 3.7 Flash is $0.05 cheaper per 1M input tokens (20% lower; 1.25x difference).

Cheaper output Mercury 2 $1.15 vs $0.75 / 1M

Mercury 2 is $0.4 cheaper per 1M output tokens (34.8% lower; 1.53x difference).

Larger context Step 3.7 Flash 256K vs 128K

Step 3.7 Flash has 128K more context (2x larger).

Sample workload Mercury 2 $0.77 vs $0.62

Mercury 2 is $0.15 cheaper on the standard workload (19.4% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.

Monthly input tokens Monthly output tokens

Step 3.7 Flash Calculating… Estimated API cost

Mercury 2 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

Step 3.7 Flash has the lower input price; Mercury 2 has the lower output price; Step 3.7 Flash offers the larger context window. For the 1M input plus 500K output sample, Mercury 2 is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $0.77 for Step 3.7 Flash and $0.62 for Mercury 2.

Best Fit

Choose Step 3.7 Flash when you care most about lower input-token price, and larger context window.

Choose Mercury 2 when you care most about lower output-token price.

Decision Notes

On the standard 1M input plus 500K output workload, Mercury 2 is estimated at $0.62 vs $0.77 for Step 3.7 Flash, saving $0.15 (19.4% lower).
Mercury 2 is $0.15 cheaper on the standard workload (19.4% lower).
Step 3.7 Flash is $0.05 cheaper per 1M input tokens (20% lower; 1.25x difference).
Mercury 2 is $0.4 cheaper per 1M output tokens (34.8% lower; 1.53x difference).
Step 3.7 Flash has 128K more context (2x larger).

Head-to-Head Specs

Feature	NewStep 3.7 Flash (StepFun)	Mercury 2 (Inception)
Input Price prompt tokens per 1M	$0.2	$0.25
Completion Price per 1M tokens	$1.15	$0.75
Sample Workload Cost 1M input + 500K output	$0.77	$0.62
Context Window	256K	128K
Release Date	2026-05-28	2026-03-04
Popularity	#101	#136

Use-Case Decision Matrix

Use case	Better pick	Why
Budget-constrained production	Mercury 2	On the standard 1M input plus 500K output workload, Mercury 2 is estimated at $0.62 vs $0.77 for Step 3.7 Flash, saving $0.15 (19.4% lower).
High-volume input processing	Step 3.7 Flash	Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbots	Mercury 2	Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document work	Step 3.7 Flash	A larger context window leaves more room for retrieved passages, conversation history, or source files.

Related Alternatives

Same-provider lower-cost swaps

Step 3.5 Flash can replace Step 3.7 Flash when lower sample workload cost matters most: $0.24.

Larger context near this budget

Llama 4 Scout offers 10M context with $0.23 sample workload cost.
Owl Alpha offers 1.05M context with $0 sample workload cost.
DeepSeek V4 Flash offers 1.05M context with $0.2 sample workload cost.
MiMo-V2.5 offers 1.05M context with $0.28 sample workload cost.

Popular competitors

Hy3 preview · Tencent · #1
DeepSeek V4 Flash · DeepSeek · #2
MiMo-V2.5 · Xiaomi · #3
Claude Sonnet 4.6 · Anthropic · #4

Cheaper alternatives

Review low-cost models sorted by a standard 1M input plus 500K output workload.

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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.

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StepFun catalog

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

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Inception catalog

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

Open Inception models

Step 3.7 Flash

Step 3.7 Flash is StepFun's latest high-efficiency multimodal Mixture-of-Experts model. It pairs a 196B-parameter language backbone with a vision encoder for native image and video understanding, activating roughly 11B parameters...

Mercury 2

Mercury 2 is an extremely fast reasoning LLM, and the first reasoning diffusion LLM (dLLM). Instead of generating tokens sequentially, Mercury 2 produces and refines multiple tokens in parallel, achieving...