API cost decision in 10 seconds

NewOpenAI GPT Luna Latest vs Step 3.7 Flash

Pick Step 3.7 Flash for lower cost; pick OpenAI GPT Luna Latest only if the larger context window matters more.

Page updated: 2026-09-11T13:07:36Z Data confirmed: 2026-09-12T06:08:18Z Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick Step 3.7 Flash for lower cost; pick OpenAI GPT Luna Latest only if the larger context window matters more.

On the standard 1M input plus 500K output workload, Step 3.7 Flash is estimated at $0.77 vs $0.8 for OpenAI GPT Luna Latest, saving $0.03 (3.1% lower).

Cost-first pickStep 3.7 Flash

Context-first pickOpenAI GPT Luna Latest

Sample savings$0.033.1%

10x traffic gap$0.25

OpenAI GPT Luna Latest has more context, but Step 3.7 Flash saves $0.03 on the standard workload. At 10x that traffic, the same price gap is about $0.25. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

Step 3.7 Flash stays cheaper across input-heavy, balanced, and output-heavy sample workloads.

Workload shape	Token mix	Better pick	OpenAI GPT Luna Latest	Step 3.7 Flash
Input-heavy / RAG	5M input + 500K output	Step 3.7 Flash	$1.6	$1.57
Balanced workload	1M input + 1M output	Step 3.7 Flash	$1.4	$1.35
Output-heavy chatbot	1M input + 5M output	Step 3.7 Flash	$6.2	$5.95

Cheaper input Tie $0.2 vs $0.2 / 1M

Both models report the same input price at $0.2 per 1M tokens.

Cheaper output Step 3.7 Flash $1.2 vs $1.15 / 1M

Step 3.7 Flash is $0.05 cheaper per 1M output tokens (4.2% lower; 1.04x difference).

Larger context OpenAI GPT Luna Latest 1.05M vs 262.14K

OpenAI GPT Luna Latest has 787.86K more context (4.01x larger).

Sample workload Step 3.7 Flash $0.8 vs $0.77

Step 3.7 Flash is $0.03 cheaper on the standard workload (3.1% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.

Monthly input tokens Monthly output tokens

OpenAI GPT Luna Latest Calculating… Estimated API cost

Step 3.7 Flash 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

both models tie on input price; Step 3.7 Flash has the lower output price; OpenAI GPT Luna Latest offers the larger context window. For the 1M input plus 500K output sample, Step 3.7 Flash is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $0.8 for OpenAI GPT Luna Latest and $0.77 for Step 3.7 Flash.

Best Fit

Choose OpenAI GPT Luna Latest when you care most about larger context window.

Choose Step 3.7 Flash when you care most about lower output-token price.

Decision Notes

On the standard 1M input plus 500K output workload, Step 3.7 Flash is estimated at $0.77 vs $0.8 for OpenAI GPT Luna Latest, saving $0.03 (3.1% lower).
Step 3.7 Flash is $0.03 cheaper on the standard workload (3.1% lower).
Both models report the same input price at $0.2 per 1M tokens.
Step 3.7 Flash is $0.05 cheaper per 1M output tokens (4.2% lower; 1.04x difference).
OpenAI GPT Luna Latest has 787.86K more context (4.01x larger).

Head-to-Head Specs

Feature	NewOpenAI GPT Luna Latest (OpenAI)	Step 3.7 Flash (StepFun)
Input Price prompt tokens per 1M	$0.2	$0.2
Completion Price per 1M tokens	$1.2	$1.15
Sample Workload Cost 1M input + 500K output	$0.8	$0.77
Context Window	1.05M	262.14K
Release Date	2026-09-11	2026-05-28

Use-Case Decision Matrix

Use case	Better pick	Why
Budget-constrained production	Step 3.7 Flash	On the standard 1M input plus 500K output workload, Step 3.7 Flash is estimated at $0.77 vs $0.8 for OpenAI GPT Luna Latest, saving $0.03 (3.1% lower).
High-volume input processing	Tie	Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbots	Step 3.7 Flash	Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document work	OpenAI GPT Luna Latest	A larger context window leaves more room for retrieved passages, conversation history, or source files.

Related Alternatives

Same-provider lower-cost swaps

gpt-oss-120b (free) can replace OpenAI GPT Luna Latest when lower sample workload cost matters most: $0.
gpt-oss-20b (free) can replace OpenAI GPT Luna Latest when lower sample workload cost matters most: $0.
gpt-oss-20b can replace OpenAI GPT Luna Latest when lower sample workload cost matters most: $0.1.
gpt-oss-120b can replace OpenAI GPT Luna Latest when lower sample workload cost matters most: $0.12.

Larger context near this budget

GLM 5.3 Flash offers 1.31M context with $0.4 sample workload cost.
DeepSeek V4 Flash 0731 offers 1.31M context with $0.08 sample workload cost.
GLM Flash Latest offers 1.31M context with $0.2 sample workload cost.
DeepSeek V4 Flash Latest offers 1.31M context with $0.08 sample workload cost.

Popular competitors

Hy4 preview · Tencent · #1
GPT-5.6 Luna · OpenAI · #2
GLM 5.3 Flash · Z.ai · #3
DeepSeek V4 Flash 0731 · DeepSeek · #4

Cheaper alternatives

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Provider catalogs

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OpenAI catalog

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StepFun catalog

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OpenAI GPT Luna Latest

This model always redirects to the latest model in the OpenAI GPT Luna family.

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...