API cost decision in 10 seconds

🔥Claude Sonnet 4.6 vs 🔥Step 3.5 Flash

Pick Step 3.5 Flash for lower cost; pick Claude Sonnet 4.6 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 Claude Sonnet 4.6 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 $10.5 for Claude Sonnet 4.6, saving $10.25 (97.6% lower).

Cost-first pickStep 3.5 Flash

Context-first pickClaude Sonnet 4.6

Sample savings$10.2597.6%

10x traffic gap$102.5

Claude Sonnet 4.6 has more context, but Step 3.5 Flash saves $10.25 on the standard workload. At 10x that traffic, the same price gap is about $102.5. Use the calculator below to replace the sample workload with your own token volume.

Cheaper input Step 3.5 Flash $3 vs $0.1 / 1M

Step 3.5 Flash is $2.9 cheaper per 1M input tokens (96.7% lower; 30x difference).

Cheaper output Step 3.5 Flash $15 vs $0.3 / 1M

Step 3.5 Flash is $14.7 cheaper per 1M output tokens (98% lower; 50x difference).

Larger context Claude Sonnet 4.6 1M vs 262.14K

Claude Sonnet 4.6 has 737.86K more context (3.81x larger).

Sample workload Step 3.5 Flash $10.5 vs $0.25

Step 3.5 Flash is $10.25 cheaper on the standard workload (97.6% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.

Monthly input tokens Monthly output tokens

Claude Sonnet 4.6 Calculating… Estimated API cost

Step 3.5 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

Step 3.5 Flash has the lower input price; Step 3.5 Flash has the lower output price; Claude Sonnet 4.6 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 $10.5 for Claude Sonnet 4.6 and $0.25 for Step 3.5 Flash.

Best Fit

Choose Claude Sonnet 4.6 when you care most about larger context window.

Choose Step 3.5 Flash 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, Step 3.5 Flash is estimated at $0.25 vs $10.5 for Claude Sonnet 4.6, saving $10.25 (97.6% lower).
Step 3.5 Flash is $10.25 cheaper on the standard workload (97.6% lower).
Step 3.5 Flash is $2.9 cheaper per 1M input tokens (96.7% lower; 30x difference).
Step 3.5 Flash is $14.7 cheaper per 1M output tokens (98% lower; 50x difference).
Claude Sonnet 4.6 has 737.86K more context (3.81x larger).

Head-to-Head Specs

Feature	🔥Claude Sonnet 4.6 (Anthropic)	🔥Step 3.5 Flash (StepFun)
Input Price prompt tokens per 1M	$3	$0.1
Completion Price per 1M tokens	$15	$0.3
Sample Workload Cost 1M input + 500K output	$10.5	$0.25
Context Window	1M	262.14K
Release Date	2026-02-17	2026-01-29
Popularity Rank current rank	#3	#15

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 $10.5 for Claude Sonnet 4.6, saving $10.25 (97.6% 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	Claude Sonnet 4.6	A larger context window leaves more room for retrieved passages, conversation history, or source files.

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