API cost decision in 10 seconds

New🔥Step 5 Preview vs Kimi K3

Pick Step 5 Preview for lower cost; pick Kimi K3 only if the larger context window matters more.

Page updated: 2026-10-15T01:07:46Z Data confirmed: 2026-10-15T01:07:46Z Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick Step 5 Preview for lower cost; pick Kimi K3 only if the larger context window matters more.

On the standard 1M input plus 500K output workload, Step 5 Preview is estimated at $2.35 vs $7.98 for Kimi K3, saving $5.63 (70.6% lower).

Cost-first pickStep 5 Preview

Context-first pickKimi K3

Sample savings$5.6370.6%

10x traffic gap$56.3

Kimi K3 has more context, but Step 5 Preview saves $5.63 on the standard workload. At 10x that traffic, the same price gap is about $56.3. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

Step 5 Preview stays cheaper across input-heavy, balanced, and output-heavy sample workloads.

Workload shape	Token mix	Better pick	Step 5 Preview	Kimi K3
Input-heavy / RAG	5M input + 500K output	Step 5 Preview	$6.35	$9.9
Balanced workload	1M input + 1M output	Step 5 Preview	$3.7	$15.48
Output-heavy chatbot	1M input + 5M output	Step 5 Preview	$14.5	$75.48

Cheaper input Kimi K3 $1 vs $0.48 / 1M

Kimi K3 is $0.52 cheaper per 1M input tokens (52% lower; 2.08x difference).

Cheaper output Step 5 Preview $2.7 vs $15 / 1M

Step 5 Preview is $12.3 cheaper per 1M output tokens (82% lower; 5.56x difference).

Larger context Kimi K3 1M vs 1.05M

Kimi K3 has 48.58K more context (1.05x larger).

Sample workload Step 5 Preview $2.35 vs $7.98

Step 5 Preview is $5.63 cheaper on the standard workload (70.6% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.

Monthly input tokens Monthly output tokens

Step 5 Preview Calculating… Estimated API cost

Kimi K3 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

Kimi K3 has the lower input price; Step 5 Preview has the lower output price; Kimi K3 offers the larger context window. For the 1M input plus 500K output sample, Step 5 Preview is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $2.35 for Step 5 Preview and $7.98 for Kimi K3.

Best Fit

Choose Step 5 Preview when you care most about lower output-token price.

Choose Kimi K3 when you care most about lower input-token price, and larger context window.

Decision Notes

On the standard 1M input plus 500K output workload, Step 5 Preview is estimated at $2.35 vs $7.98 for Kimi K3, saving $5.63 (70.6% lower).
Step 5 Preview is $5.63 cheaper on the standard workload (70.6% lower).
Kimi K3 is $0.52 cheaper per 1M input tokens (52% lower; 2.08x difference).
Step 5 Preview is $12.3 cheaper per 1M output tokens (82% lower; 5.56x difference).
Kimi K3 has 48.58K more context (1.05x larger).

Head-to-Head Specs

Feature	New🔥Step 5 Preview (StepFun)	Kimi K3 (MoonshotAI)
Input Price prompt tokens per 1M	$1	$0.48
Completion Price per 1M tokens	$2.7	$15
Sample Workload Cost 1M input + 500K output	$2.35	$7.98
Context Window	1M	1.05M
Release Date	2026-10-08	2026-07-16
Popularity	#2

Use-Case Decision Matrix

Use case	Better pick	Why
Budget-constrained production	Step 5 Preview	On the standard 1M input plus 500K output workload, Step 5 Preview is estimated at $2.35 vs $7.98 for Kimi K3, saving $5.63 (70.6% lower).
High-volume input processing	Kimi K3	Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbots	Step 5 Preview	Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document work	Kimi K3	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 5 Preview when lower sample workload cost matters most: $0.25.
Step 3.7 Flash can replace Step 5 Preview when lower sample workload cost matters most: $0.77.
Kimi K2.7 Code (free) can replace Kimi K3 when lower sample workload cost matters most: $0.
Kimi K2.6 (free) can replace Kimi K3 when lower sample workload cost matters most: $0.

Larger context near this budget

Grok 4.20 Multi-Agent offers 2M context with $2.5 sample workload cost.
Grok 4.20 offers 2M context with $2.5 sample workload cost.
Llama 4 Scout offers 1.31M context with $0.47 sample workload cost.
MiMo-V2.6-Flash offers 1.05M context with $0.28 sample workload cost.

Popular competitors

DeepSeek V4.1 Flash · DeepSeek · #1
GLM 5.3 Flash · Z.ai · #3
MiMo-V2.6-Flash · Xiaomi · #4
Hy4 preview · Tencent · #5

Cheaper alternatives

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Larger context alternatives

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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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MoonshotAI catalog

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

Open MoonshotAI models

Step 5 Preview

Step 5 Preview is StepFun's flagship model for agentic work, built on a sparse Mixture-of-Experts architecture (27B active / 600B total parameters). It performs strongly in software engineering and professional...

Kimi K3

Kimi K3 is a 2.8T parameter open-weight multimodal reasoning model from Moonshot AI. It is suited for complex coding, knowledge work, and long-horizon agentic workflows, and is particularly strong at...