API cost decision in 10 seconds

🔥Step 3.5 Flash vs 🔥Grok 4.1 Fast

Pick Step 3.5 Flash for lower cost; pick Grok 4.1 Fast only if the larger context window matters more.

Pricing data updated: 2026-05-13T16:32:23Z Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick Step 3.5 Flash for lower cost; pick Grok 4.1 Fast only if the larger context window matters more.

On the standard 1M input plus 500K output workload, Step 3.5 Flash is estimated at $0.25 vs $0.45 for Grok 4.1 Fast, saving $0.2 (44.4% lower).

Cost-first pickStep 3.5 Flash

Context-first pickGrok 4.1 Fast

Sample savings$0.244.4%

10x traffic gap$2

Grok 4.1 Fast has more context, but Step 3.5 Flash saves $0.2 on the standard workload. At 10x that traffic, the same price gap is about $2. Use the calculator below to replace the sample workload with your own token volume.

Cheaper input Step 3.5 Flash $0.1 vs $0.2 / 1M

Step 3.5 Flash is $0.1 cheaper per 1M input tokens (50% lower; 2x difference).

Cheaper output Step 3.5 Flash $0.3 vs $0.5 / 1M

Step 3.5 Flash is $0.2 cheaper per 1M output tokens (40% lower; 1.67x difference).

Larger context Grok 4.1 Fast 262.14K vs 2M

Grok 4.1 Fast has 1.74M more context (7.63x larger).

Sample workload Step 3.5 Flash $0.25 vs $0.45

Step 3.5 Flash is $0.2 cheaper on the standard workload (44.4% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.

Monthly input tokens Monthly output tokens

Step 3.5 Flash Calculating… Estimated API cost

Grok 4.1 Fast 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 3.5 Flash has the lower input price; Step 3.5 Flash has the lower output price; Grok 4.1 Fast offers the larger context window. For the 1M input plus 500K output sample, Step 3.5 Flash is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $0.25 for Step 3.5 Flash and $0.45 for Grok 4.1 Fast.

Best Fit

Choose Step 3.5 Flash when you care most about lower input-token price, and lower output-token price.

Choose Grok 4.1 Fast when you care most about larger context window.

Decision Notes

On the standard 1M input plus 500K output workload, Step 3.5 Flash is estimated at $0.25 vs $0.45 for Grok 4.1 Fast, saving $0.2 (44.4% lower).
Step 3.5 Flash is $0.2 cheaper on the standard workload (44.4% lower).
Step 3.5 Flash is $0.1 cheaper per 1M input tokens (50% lower; 2x difference).
Step 3.5 Flash is $0.2 cheaper per 1M output tokens (40% lower; 1.67x difference).
Grok 4.1 Fast has 1.74M more context (7.63x larger).

Head-to-Head Specs

Feature	🔥Step 3.5 Flash (StepFun)	🔥Grok 4.1 Fast (xAI)
Input Price prompt tokens per 1M	$0.1	$0.2
Completion Price per 1M tokens	$0.3	$0.5
Sample Workload Cost 1M input + 500K output	$0.25	$0.45
Context Window	262.14K	2M
Release Date	2026-01-29	2025-11-19
Popularity Rank current rank	#15	#18

Use-Case Decision Matrix

Use case	Better pick	Why
Budget-constrained production	Step 3.5 Flash	On the standard 1M input plus 500K output workload, Step 3.5 Flash is estimated at $0.25 vs $0.45 for Grok 4.1 Fast, saving $0.2 (44.4% lower).
High-volume input processing	Step 3.5 Flash	Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbots	Step 3.5 Flash	Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document work	Grok 4.1 Fast	A larger context window leaves more room for retrieved passages, conversation history, or source files.

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