API cost decision in 10 seconds

🔥GPT-4o-mini vs GPT-5.1

Pick GPT-4o-mini for lower cost; pick GPT-5.1 only if the larger context window matters more.

Page updated: 2026-05-26T12:03:47Z Data confirmed: 2026-05-26T14:08:03Z Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick GPT-4o-mini for lower cost; pick GPT-5.1 only if the larger context window matters more.

On the standard 1M input plus 500K output workload, GPT-4o-mini is estimated at $0.45 vs $6.25 for GPT-5.1, saving $5.8 (92.8% lower).

Cost-first pickGPT-4o-mini

Context-first pickGPT-5.1

Sample savings$5.892.8%

10x traffic gap$58

GPT-5.1 has more context, but GPT-4o-mini saves $5.8 on the standard workload. At 10x that traffic, the same price gap is about $58. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

GPT-4o-mini stays cheaper across input-heavy, balanced, and output-heavy sample workloads.

Workload shape	Token mix	Better pick	GPT-4o-mini	GPT-5.1
Input-heavy / RAG	5M input + 500K output	GPT-4o-mini	$1.05	$11.25
Balanced workload	1M input + 1M output	GPT-4o-mini	$0.75	$11.25
Output-heavy chatbot	1M input + 5M output	GPT-4o-mini	$3.15	$51.25

Cheaper input GPT-4o-mini $0.15 vs $1.25 / 1M

GPT-4o-mini is $1.1 cheaper per 1M input tokens (88% lower; 8.33x difference).

Cheaper output GPT-4o-mini $0.6 vs $10 / 1M

GPT-4o-mini is $9.4 cheaper per 1M output tokens (94% lower; 16.7x difference).

Larger context GPT-5.1 128K vs 400K

GPT-5.1 has 272K more context (3.12x larger).

Sample workload GPT-4o-mini $0.45 vs $6.25

GPT-4o-mini is $5.8 cheaper on the standard workload (92.8% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.

Monthly input tokens Monthly output tokens

GPT-4o-mini Calculating… Estimated API cost

GPT-5.1 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

GPT-4o-mini has the lower input price; GPT-4o-mini has the lower output price; GPT-5.1 offers the larger context window. For the 1M input plus 500K output sample, GPT-4o-mini is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $0.45 for GPT-4o-mini and $6.25 for GPT-5.1.

Best Fit

Choose GPT-4o-mini when you care most about lower input-token price, and lower output-token price.

Choose GPT-5.1 when you care most about larger context window.

Decision Notes

On the standard 1M input plus 500K output workload, GPT-4o-mini is estimated at $0.45 vs $6.25 for GPT-5.1, saving $5.8 (92.8% lower).
GPT-4o-mini is $5.8 cheaper on the standard workload (92.8% lower).
GPT-4o-mini is $1.1 cheaper per 1M input tokens (88% lower; 8.33x difference).
GPT-4o-mini is $9.4 cheaper per 1M output tokens (94% lower; 16.7x difference).
GPT-5.1 has 272K more context (3.12x larger).

Head-to-Head Specs

Feature	🔥GPT-4o-mini (OpenAI)	GPT-5.1 (OpenAI)
Input Price prompt tokens per 1M	$0.15	$1.25
Completion Price per 1M tokens	$0.6	$10
Sample Workload Cost 1M input + 500K output	$0.45	$6.25
Context Window	128K	400K
Release Date	2024-07-18	2025-11-13
Popularity	#16

Use-Case Decision Matrix

Use case	Better pick	Why
Budget-constrained production	GPT-4o-mini	On the standard 1M input plus 500K output workload, GPT-4o-mini is estimated at $0.45 vs $6.25 for GPT-5.1, saving $5.8 (92.8% lower).
High-volume input processing	GPT-4o-mini	Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbots	GPT-4o-mini	Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document work	GPT-5.1	A larger context window leaves more room for retrieved passages, conversation history, or source files.

Related Alternatives

Same-provider lower-cost swaps

gpt-oss-120b (free) can replace GPT-4o-mini when lower sample workload cost matters most: $0.
gpt-oss-20b (free) can replace GPT-4o-mini when lower sample workload cost matters most: $0.
gpt-oss-20b can replace GPT-4o-mini when lower sample workload cost matters most: $0.1.
gpt-oss-120b can replace GPT-4o-mini when lower sample workload cost matters most: $0.13.

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.
Owl Alpha offers 1.05M context with $0 sample workload cost.

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Cheaper alternatives

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Larger context alternatives

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Provider catalogs

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Open provider hubs

OpenAI catalog

Review all tracked OpenAI models before deciding whether this matchup is the right shortlist.

Open OpenAI models

GPT-4o-mini

GPT-4o mini is OpenAI's newest model after [GPT-4 Omni](/models/openai/gpt-4o), supporting both text and image inputs with text outputs. As their most advanced small model, it is many multiples more affordable...

GPT-5.1

GPT-5.1 is the latest frontier-grade model in the GPT-5 series, offering stronger general-purpose reasoning, improved instruction adherence, and a more natural conversational style compared to GPT-5. It uses adaptive reasoning...