API cost decision in 10 seconds

🔥Step 3.5 Flash vs NewAnthropic Claude Sonnet Latest

Pick Step 3.5 Flash for lower cost; pick Anthropic Claude Sonnet Latest only if the larger context window matters more.

Pricing data updated: 2026-05-19T10:07:39Z Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

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

Cost-first pickStep 3.5 Flash

Context-first pickAnthropic Claude Sonnet Latest

Sample savings$10.2597.6%

10x traffic gap$102.5

Anthropic Claude Sonnet Latest 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.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

Step 3.5 Flash stays cheaper across input-heavy, balanced, and output-heavy sample workloads.

Workload shape	Token mix	Better pick	Step 3.5 Flash	Anthropic Claude Sonnet Latest
Input-heavy / RAG	5M input + 500K output	Step 3.5 Flash	$0.65	$22.5
Balanced workload	1M input + 1M output	Step 3.5 Flash	$0.4	$18
Output-heavy chatbot	1M input + 5M output	Step 3.5 Flash	$1.6	$78

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

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

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

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

Larger context Anthropic Claude Sonnet Latest 262.14K vs 1M

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

Sample workload Step 3.5 Flash $0.25 vs $10.5

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

Step 3.5 Flash Calculating… Estimated API cost

Anthropic Claude Sonnet Latest 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; Anthropic Claude Sonnet Latest 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 $10.5 for Anthropic Claude Sonnet Latest.

Best Fit

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

Choose Anthropic Claude Sonnet Latest 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 $10.5 for Anthropic Claude Sonnet Latest, 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).
Anthropic Claude Sonnet Latest has 737.86K more context (3.81x larger).

Head-to-Head Specs

Feature	🔥Step 3.5 Flash (StepFun)	NewAnthropic Claude Sonnet Latest (Anthropic)
Input Price prompt tokens per 1M	$0.1	$3
Completion Price per 1M tokens	$0.3	$15
Sample Workload Cost 1M input + 500K output	$0.25	$10.5
Context Window	262.14K	1M
Release Date	2026-01-29	2026-04-27
Popularity	#10

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 Anthropic Claude Sonnet Latest, 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	Anthropic Claude Sonnet Latest	A larger context window leaves more room for retrieved passages, conversation history, or source files.

Related Alternatives

Same-provider lower-cost swaps

Claude 3 Haiku can replace Anthropic Claude Sonnet Latest when lower sample workload cost matters most: $0.88.
Claude 3.5 Haiku can replace Anthropic Claude Sonnet Latest when lower sample workload cost matters most: $2.8.
Anthropic Claude Haiku Latest can replace Anthropic Claude Sonnet Latest when lower sample workload cost matters most: $3.5.
Claude Haiku 4.5 can replace Anthropic Claude Sonnet Latest when lower sample workload cost matters most: $3.5.

Larger context near this budget

Llama 4 Scout offers 10M context with $0.23 sample workload cost.
Grok 4.20 Multi-Agent offers 2M context with $5 sample workload cost.
Grok 4.20 offers 2M context with $2.5 sample workload cost.
GPT-5.4 offers 1.05M context with $10 sample workload cost.

Popular competitors

Hy3 preview · Tencent · #1
DeepSeek V4 Flash · DeepSeek · #2
Claude Sonnet 4.6 · Anthropic · #3
Owl Alpha · OpenRouter · #4

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StepFun catalog

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Anthropic catalog

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Step 3.5 Flash is StepFun's most capable open-source foundation model. Built on a sparse Mixture of Experts (MoE) architecture, it selectively activates only 11B of its 196B parameters per token....

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