API cost decision in 10 seconds

NewGrok Build 0.1 vs Gemini 3.1 Pro Preview Custom Tools

Pick Grok Build 0.1 for lower cost; pick Gemini 3.1 Pro Preview Custom Tools only if the larger context window matters more.

Page updated: 2026-05-26T10:03:26Z Data confirmed: 2026-05-26T12:43:06Z Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick Grok Build 0.1 for lower cost; pick Gemini 3.1 Pro Preview Custom Tools only if the larger context window matters more.

On the standard 1M input plus 500K output workload, Grok Build 0.1 is estimated at $2 vs $8 for Gemini 3.1 Pro Preview Custom Tools, saving $6 (75% lower).

Cost-first pickGrok Build 0.1

Context-first pickGemini 3.1 Pro Preview Custom Tools

Sample savings$675%

10x traffic gap$60

Gemini 3.1 Pro Preview Custom Tools has more context, but Grok Build 0.1 saves $6 on the standard workload. At 10x that traffic, the same price gap is about $60. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

Grok Build 0.1 stays cheaper across input-heavy, balanced, and output-heavy sample workloads.

Workload shape	Token mix	Better pick	Grok Build 0.1	Gemini 3.1 Pro Preview Custom Tools
Input-heavy / RAG	5M input + 500K output	Grok Build 0.1	$6	$16
Balanced workload	1M input + 1M output	Grok Build 0.1	$3	$14
Output-heavy chatbot	1M input + 5M output	Grok Build 0.1	$11	$62

Cheaper input Grok Build 0.1 $1 vs $2 / 1M

Grok Build 0.1 is $1 cheaper per 1M input tokens (50% lower; 2x difference).

Cheaper output Grok Build 0.1 $2 vs $12 / 1M

Grok Build 0.1 is $10 cheaper per 1M output tokens (83.3% lower; 6x difference).

Larger context Gemini 3.1 Pro Preview Custom Tools 256K vs 1.05M

Gemini 3.1 Pro Preview Custom Tools has 792.76K more context (4.1x larger).

Sample workload Grok Build 0.1 $2 vs $8

Grok Build 0.1 is $6 cheaper on the standard workload (75% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.

Monthly input tokens Monthly output tokens

Grok Build 0.1 Calculating… Estimated API cost

Gemini 3.1 Pro Preview Custom Tools 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

Grok Build 0.1 has the lower input price; Grok Build 0.1 has the lower output price; Gemini 3.1 Pro Preview Custom Tools offers the larger context window. For the 1M input plus 500K output sample, Grok Build 0.1 is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $2 for Grok Build 0.1 and $8 for Gemini 3.1 Pro Preview Custom Tools.

Best Fit

Choose Grok Build 0.1 when you care most about lower input-token price, and lower output-token price.

Choose Gemini 3.1 Pro Preview Custom Tools when you care most about larger context window.

Decision Notes

On the standard 1M input plus 500K output workload, Grok Build 0.1 is estimated at $2 vs $8 for Gemini 3.1 Pro Preview Custom Tools, saving $6 (75% lower).
Grok Build 0.1 is $6 cheaper on the standard workload (75% lower).
Grok Build 0.1 is $1 cheaper per 1M input tokens (50% lower; 2x difference).
Grok Build 0.1 is $10 cheaper per 1M output tokens (83.3% lower; 6x difference).
Gemini 3.1 Pro Preview Custom Tools has 792.76K more context (4.1x larger).

Head-to-Head Specs

Feature	NewGrok Build 0.1 (xAI)	Gemini 3.1 Pro Preview Custom Tools (Google)
Input Price prompt tokens per 1M	$1	$2
Completion Price per 1M tokens	$2	$12
Sample Workload Cost 1M input + 500K output	$2	$8
Context Window	256K	1.05M
Release Date	2026-05-20	2026-02-25

Use-Case Decision Matrix

Use case	Better pick	Why
Budget-constrained production	Grok Build 0.1	On the standard 1M input plus 500K output workload, Grok Build 0.1 is estimated at $2 vs $8 for Gemini 3.1 Pro Preview Custom Tools, saving $6 (75% lower).
High-volume input processing	Grok Build 0.1	Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbots	Grok Build 0.1	Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document work	Gemini 3.1 Pro Preview Custom Tools	A larger context window leaves more room for retrieved passages, conversation history, or source files.

Related Alternatives

Same-provider lower-cost swaps

Gemma 4 26B A4B (free) can replace Gemini 3.1 Pro Preview Custom Tools when lower sample workload cost matters most: $0.
Gemma 4 31B (free) can replace Gemini 3.1 Pro Preview Custom Tools when lower sample workload cost matters most: $0.
Lyria 3 Pro Preview can replace Gemini 3.1 Pro Preview Custom Tools when lower sample workload cost matters most: $0.
Lyria 3 Clip Preview can replace Gemini 3.1 Pro Preview Custom Tools when lower sample workload cost matters most: $0.

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.

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