API cost decision in 10 seconds

Inkling (free) vs GPT-5.6 Terra Pro (batch)

Pick Inkling (free) for lower cost; pick GPT-5.6 Terra Pro (batch) only if the larger context window matters more.

Page updated:  Data confirmed:  Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick Inkling (free) for lower cost; pick GPT-5.6 Terra Pro (batch) only if the larger context window matters more.

On the standard 1M input plus 500K output workload, Inkling (free) is estimated at $0 vs $4 for GPT-5.6 Terra Pro (batch), saving $4 (100% lower).

Cost-first pickInkling (free)
Context-first pickGPT-5.6 Terra Pro (batch)
Sample savings$4100%
10x traffic gap$40

GPT-5.6 Terra Pro (batch) has more context, but Inkling (free) saves $4 on the standard workload. At 10x that traffic, the same price gap is about $40. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

Inkling (free) stays cheaper across input-heavy, balanced, and output-heavy sample workloads.

Workload shapeToken mixBetter pickInkling (free)GPT-5.6 Terra Pro (batch)
Input-heavy / RAG5M input + 500K outputInkling (free)$0$8
Balanced workload1M input + 1M outputInkling (free)$0$7
Output-heavy chatbot1M input + 5M outputInkling (free)$0$31
Cheaper input Inkling (free) $0 vs $1 / 1M

Inkling (free) is free for input tokens while GPT-5.6 Terra Pro (batch) costs $1 per 1M tokens.

Cheaper output Inkling (free) $0 vs $6 / 1M

Inkling (free) is free for output tokens while GPT-5.6 Terra Pro (batch) costs $6 per 1M tokens.

Larger context GPT-5.6 Terra Pro (batch) 262.14K vs 1.05M

GPT-5.6 Terra Pro (batch) has 787.86K more context (4.01x larger).

Sample workload Inkling (free) $0 vs $4

Inkling (free) is free for the standard workload while the other model is estimated at $4.

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.
Inkling (free) Calculating… Estimated API cost
GPT-5.6 Terra Pro (batch) 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

Inkling (free) has the lower input price; Inkling (free) has the lower output price; GPT-5.6 Terra Pro (batch) offers the larger context window. For the 1M input plus 500K output sample, Inkling (free) is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $0 for Inkling (free) and $4 for GPT-5.6 Terra Pro (batch).

Best Fit

Choose Inkling (free) when you care most about lower input-token price, and lower output-token price.

Choose GPT-5.6 Terra Pro (batch) when you care most about larger context window.

Decision Notes
  • On the standard 1M input plus 500K output workload, Inkling (free) is estimated at $0 vs $4 for GPT-5.6 Terra Pro (batch), saving $4 (100% lower).
  • Inkling (free) is free for the standard workload while the other model is estimated at $4.
  • Inkling (free) is free for input tokens while GPT-5.6 Terra Pro (batch) costs $1 per 1M tokens.
  • Inkling (free) is free for output tokens while GPT-5.6 Terra Pro (batch) costs $6 per 1M tokens.
  • GPT-5.6 Terra Pro (batch) has 787.86K more context (4.01x larger).
Head-to-Head Specs
FeatureInkling (free)
(Thinking Machines)		GPT-5.6 Terra Pro (batch)
(OpenAI)
Input Price
prompt tokens per 1M		$0$1
Completion Price
per 1M tokens		$0$6
Sample Workload Cost
1M input + 500K output		$0$4
Context Window262.14K1.05M
Release Date

Use-Case Decision Matrix

Use caseBetter pickWhy
Budget-constrained productionInkling (free)On the standard 1M input plus 500K output workload, Inkling (free) is estimated at $0 vs $4 for GPT-5.6 Terra Pro (batch), saving $4 (100% lower).
High-volume input processingInkling (free)Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbotsInkling (free)Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document workGPT-5.6 Terra Pro (batch)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-5.6 Terra Pro (batch) when lower sample workload cost matters most: $0.
  • gpt-oss-20b (free) can replace GPT-5.6 Terra Pro (batch) when lower sample workload cost matters most: $0.
  • gpt-oss-20b can replace GPT-5.6 Terra Pro (batch) when lower sample workload cost matters most: $0.1.
  • gpt-oss-120b can replace GPT-5.6 Terra Pro (batch) when lower sample workload cost matters most: $0.12.

Cheaper alternatives

Review low-cost models sorted by a standard 1M input plus 500K output workload.

Open cheapest models

Larger context alternatives

Find models with larger context windows for RAG, long documents, and codebase review.

Open largest context models

Provider catalogs

Compare models within provider hubs before choosing a final API vendor.

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Thinking Machines catalog

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

Open Thinking Machines models

OpenAI catalog

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

Open OpenAI models
Inkling (free)

Inkling is an open-weight multimodal mixture-of-experts model from Thinking Machines Lab, with 41B active parameters out of 975B total. It is designed for general-purpose reasoning, coding, agentic and tool-use systems,...

GPT-5.6 Terra Pro (batch)

GPT-5.6 Terra Pro is the same underlying model as [GPT-5.6 Terra](https://openrouter.ai/openai/gpt-5.6-terra), served with `reasoning.mode` set to `pro` for higher-quality responses on complex tasks. Learn more in OpenAI's docs: https://developers.openai.com/api/docs/guides/reasoning#reasoning-mode