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Head-to-head comparison

Mistral Medium 3.5 vs GPT-5.6 Luna

Mistral Medium 3.5 (Mistral AI) and GPT-5.6 Luna (OpenAI) compared on the ModelCap Index, API price, context window, provider availability, weight access and every public benchmark board they share. Figures are the same ones shown on the live rankings; nothing here is a hidden score.

Snapshot as of 18 August 2026

As of 18 August 2026, GPT-5.6 Luna holds the stronger ModelCap Index position (#17 vs #38); GPT-5.6 Luna is 6.3× cheaper per output token ($1.20/1M vs $7.50/1M); and GPT-5.6 Luna offers the longer context window (1M vs 262K tokens).

Which should you choose?

Choose Mistral Medium 3.5 if…

  • ModelCap publishes no field on which Mistral Medium 3.5 leads GPT-5.6 Luna for this pair.

Choose GPT-5.6 Luna if…

  • you want the stronger overall ModelCap Index position — #17 against #38 (67.9 vs 53.9 points).
  • API cost matters — $1.20/1M output tokens against $7.50/1M, about 6.3× cheaper.
  • your workload is prompt-heavy — input tokens cost $0.20/1M against $1.50/1M.
  • you need the longer context window — 1M tokens against 262K.
  • you want provider choice — 3 listed API providers against 1.
  • Arena coding is your yardstick — 1498 against 1479.
  • LMArena Agent is your yardstick — 4.3% against -7.0%.
  • Artificial Analysis Intelligence Index is your yardstick — 52.3 against 30.4.
  • you want the more recently listed model — GPT-5.6 Luna was listed 9 July 2026, Mistral Medium 3.5 30 April 2026.

Mistral Medium 3.5 vs GPT-5.6 Luna: specs, pricing and context

Specification comparison of Mistral Medium 3.5 and GPT-5.6 Luna
FieldMistral Medium 3.5Mistral AIGPT-5.6 LunaOpenAI
ModelCap Index position#38#17
Index score53.967.9
EvidenceMeasuredMeasured
Input price / 1M tokens$1.50$0.20
Output price / 1M tokens$7.50$1.20
Context window262K tokens1M tokens
Max output tokens—128K
API providers listed13
Weight accessAPI onlyAPI only
Input modalitiesText, Image, FileFile, Image, Text
First listed30 April 20269 July 2026
PublisherMistral AIOpenAI

Evidence: 4 public benchmark observations across 4 boards · 6 public benchmark observations across 6 boards. Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.

Benchmark scores: Mistral Medium 3.5 vs GPT-5.6 Luna

Public benchmark boards where Mistral Medium 3.5 or GPT-5.6 Luna has a published result
BoardMistral Medium 3.5GPT-5.6 LunaLeads
Arena codingArena (LMArena)14791468–149014981489–1508X-HighGPT-5.6 Luna
LMArena AgentLMArena-7.0%-9.0%–-5.0%4.3%2.4%–6.2%X-HighGPT-5.6 Luna
ARC-AGI-2ARC Prize Foundation—59.6%MaxOnly one result
ARC-AGI-3ARC Prize Foundation—0.2%MaxOnly one result
Artificial Analysis Intelligence IndexArtificial Analysis30.4intelligence-index52.3intelligence-indexGPT-5.6 Luna

Scores are the sources' own published figures for each model's best evaluated configuration; ModelCap never re-runs a benchmark.

Want a different pairing? Open the interactive comparison tool to swap either model for any current ranked language model.

Mistral Medium 3.5 vs GPT-5.6 Luna: common questions

Is Mistral Medium 3.5 better than GPT-5.6 Luna?

GPT-5.6 Luna ranks higher on the ModelCap Index as of 18 August 2026: #17 against #38. That is a capability ranking built from public benchmark evidence with published uncertainty; whether it is "better" for you also depends on price, context and where you can run it.

Is Mistral Medium 3.5 cheaper than GPT-5.6 Luna?

GPT-5.6 Luna is cheaper on output tokens: $1.20/1M against $7.50/1M. Input tokens are $1.50/1M for Mistral Medium 3.5 and $0.20/1M for GPT-5.6 Luna. Prices are the lowest listed API offer ModelCap observed, in USD per million tokens.

Which has the bigger context window, Mistral Medium 3.5 or GPT-5.6 Luna?

GPT-5.6 Luna has the larger context window: 1M tokens against 262K.

Which is better for coding, Mistral Medium 3.5 or GPT-5.6 Luna?

Arena coding: Mistral Medium 3.5 1479, GPT-5.6 Luna 1498 — GPT-5.6 Luna leads.

Are Mistral Medium 3.5 and GPT-5.6 Luna open-weight models?

Mistral Medium 3.5: API only. GPT-5.6 Luna: API only. Open weights mean the checkpoint can be downloaded and self-hosted under its licence; API-only models are available solely through hosted endpoints.

Where can I run Mistral Medium 3.5 and GPT-5.6 Luna?

ModelCap currently lists 1 API provider for Mistral Medium 3.5 and 3 for GPT-5.6 Luna, from the OpenRouter catalogue snapshot the site serves; each model page lists the providers and their prices.

How current is this Mistral Medium 3.5 vs GPT-5.6 Luna comparison?

Every figure comes from the sealed ModelCap dataset published 18 August 2026; the page re-renders within a minute of each data refresh, and the ModelCap Index positions are the same ones shown on the live rankings.

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