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A · closed · GPT-5.x

GPT-5.4 Mini

OpenAI

B · closed · GPT-5.x

GPT-5.6 Luna

OpenAI

0:13

overall capability wins (1 ties across 14 scored). GPT-5.6 Luna leads overall.

  • Reasoning0:6
  • Coding0:4
  • Arena0:1
  • Tool use0:1
  • Composite indices0:2
  • Pricing0:3
  • Speed0:2
  • Specs0:1

Verdict

GPT-5.6 Luna leads coding (widest gap: +121.7 on WebDev Elo); GPT-5.6 Luna ranks higher on LMArena (+4 Elo); GPT-5.6 Luna offers ~2.6x larger context (1.1M vs 400K).

  • GPT-5.6 Luna leads coding (widest gap: +121.7 on WebDev Elo)
  • GPT-5.6 Luna ranks higher on LMArena (+4 Elo)
  • GPT-5.6 Luna offers ~2.6x larger context (1.1M vs 400K)
  • GPT-5.6 Luna is ~3.8x cheaper on a blended token basis than GPT-5.4 Mini

Cost for 1M in + 250K out

Illustrative chat workload at primary-provider list prices.

GPT-5.4 Mini
$1.88
GPT-5.6 Luna
$0.50

GPT-5.6 Luna is about 3.8x cheaper on this workload.

Price per 1M tokens

Full comparison

Organization

OpenAI

OpenAI

Family

GPT-5.x

GPT-5.x

License

Proprietary

Proprietary

Open weights

No

No

Release

Mar 17, 2026

Jul 9, 2026

Knowledge cutoff

-

-

API / provider

OpenAI

OpenAI

Modalities

text, image → text

text, image → text

Specs

Context window

400K

1.1M

B +650K

Max output

128K

128K

tie

Parameters

—

—

—

Pricing

Input $/1M

$0.75

$0.20

B +$0.55

Output $/1M

$4.50

$1.20

B +$3.30

Blended $/1M (3∶1)

$1.69

$0.45

B +$1.24

Speed

tok/s

130

195

B +65

TTFT (s)

0.25

0.2

B +0.05

Reasoning

MMLU-Pro

—

—

—

GPQA Diamond

87.5

91.1

B +3.6 pts

Humanity's Last Exam

28.1

39.5

B +11.4 pts

AIME 2025

—

—

—

MATH-500

—

—

—

Humanity's Last Exam (with tools)

—

—

—

AA-Omniscience Accuracy

37.5

42.7

B +5.2 pts

AA-LCR v1.1

77.0

83.7

B +6.7 pts

CritPt

10.0

20.6

B +10.6 pts

MMMU-Pro

73.3

78.6

B +5.3 pts

IFBench

73.3

—

—

Chartography

—

—

—

Chartography (With Tools)

—

—

—

Coding

SWE-bench Verified

—

—

—

SWE-bench Pro

54.4

62.7

B +8.3 pts

SWE-bench Multilingual

—

—

—

LiveCodeBench

—

—

—

Terminal-Bench 2.1

59.2

80.9

B +21.7 pts

Aider Polyglot

—

—

—

Terminal-Bench 3

—

14.3

—

BigCodeBench

—

—

—

SciCode

52.1

53.6

B +1.5 pts

CursorBench

—

61.1

—

SWE-Rebench

—

43.6

—

NL2Repo-Bench

—

—

—

DeepSWE

—

67.0

—

WebDev Arena

1,397

1,519

B +122 Elo

Terminal-Bench 4.0

—

17.3

—

CursorBench 4.0

—

—

—

FrontierCode v1.1 (Main)

—

—

—

Arena

LMArena Elo

1,448

1,453

B +4 Elo

GPT-5.4 Mini

Context
400K / 128K out
Parameters
—
Price
$0.75 / $4.50
Speed
130 tok/s · 0.25s TTFT
Modalities
text, image → text
License
Proprietary

Efficient GPT-5.4 small model approaching full 5.4 quality on coding and computer-use tasks.

GPT-5.6 Luna

Context
1.1M / 128K out
Parameters
—
Price
$0.20 / $1.20
Speed
195 tok/s · 0.2s TTFT
Modalities
text, image → text
License
Proprietary

Fastest, cheapest GPT-5.6 tier for high-volume chat, classification, and light coding; July 30, 2026 API cut dropped Standard rates 80% to $0.20/$1.20.

Benchmark charts

Winner bars are emphasized. Per-benchmark deltas sit above each chart.

Reasoning & knowledge

GPQA: B +3.6HLE: B +11.4CritPt: B +10.6AA-LCR: B +6.7Omniscience Acc.: B +5.2MMMU-Pro: B +5.3

Coding

SWE-Pro: B +8.3TermBench: B +21.7SciCode: B +1.5WebDev Elo: B +122

Tool use & function calling

τ³-Banking: B +5.5

Arena

Arena Elo: B +4

Composite indices

AA Index: B +18.8AA Index v4.3: B +12.9

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