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A · closed · GPT-5.x

GPT-5.4 Nano

OpenAI

B · closed · GPT-5.x

GPT-5.6 Sol

OpenAI

1:12

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

  • Reasoning1:6
  • Coding0:3
  • Arena0:1
  • Tool use0:1
  • Composite indices0:2
  • Pricing3:0
  • Speed2:0
  • Specs0:1

Verdict

GPT-5.6 Sol leads coding (widest gap: +27.3 on TermBench); GPT-5.6 Sol ranks higher on LMArena (+81 Elo); GPT-5.6 Sol offers ~2.6x larger context (1.1M vs 400K).

  • GPT-5.6 Sol leads coding (widest gap: +27.3 on TermBench)
  • GPT-5.6 Sol ranks higher on LMArena (+81 Elo)
  • GPT-5.6 Sol offers ~2.6x larger context (1.1M vs 400K)
  • GPT-5.4 Nano is ~17.3x cheaper on a blended token basis than GPT-5.6 Sol

Cost for 1M in + 250K out

Illustrative chat workload at primary-provider list prices.

GPT-5.4 Nano
$0.51
GPT-5.6 Sol
$9

GPT-5.4 Nano is about 17.6x 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

-

2026-02-16

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

$0.20

$4

A +$3.80

Output $/1M

$1.25

$20

A +$18.75

Blended $/1M (3∶1)

$0.46

$8

A +$7.54

Speed

tok/s

180

96

A +84

TTFT (s)

0.18

0.45

A +0.27

Reasoning

MMLU-Pro

—

—

—

GPQA Diamond

81.7

94.1

B +12.4 pts

Humanity's Last Exam

28.3

49.5

B +21.2 pts

AIME 2025

—

—

—

MATH-500

—

—

—

Humanity's Last Exam (with tools)

—

—

—

AA-Omniscience Accuracy

25.7

59.4

B +33.7 pts

AA-LCR v1.1

76.7

84.0

B +7.3 pts

CritPt

9.3

32.3

B +23.0 pts

MMMU-Pro

65.4

83.4

B +18.0 pts

IFBench

75.9

72.7

A +3.2 pts

Chartography

—

—

—

Chartography (With Tools)

—

—

—

Coding

SWE-bench Verified

—

—

—

SWE-bench Pro

52.4

64.6

B +12.2 pts

SWE-bench Multilingual

—

—

—

LiveCodeBench

—

—

—

Terminal-Bench 2.1

60.7

88.0

B +27.3 pts

Aider Polyglot

—

—

—

Terminal-Bench 3

—

34.6

—

BigCodeBench

—

—

—

SciCode

47.2

57.1

B +9.9 pts

CursorBench

—

67.2

—

SWE-Rebench

—

62.3

—

NL2Repo-Bench

—

—

—

DeepSWE

—

72.7

—

WebDev Arena

—

1,617

—

Terminal-Bench 4.0

—

37.3

—

CursorBench 4.0

—

—

—

FrontierCode v1.1 (Main)

—

—

—

Arena

LMArena Elo

1,402

1,484

B +81 Elo

GPT-5.4 Nano

Context
400K / 128K out
Parameters
—
Price
$0.20 / $1.25
Speed
180 tok/s · 0.18s TTFT
Modalities
text, image → text
License
Proprietary

Cheapest GPT-5.4 tier for high-volume classification and light assistants.

GPT-5.6 Sol

Context
1.1M / 128K out
Parameters
—
Price
$4 / $20
Speed
96 tok/s · 0.45s TTFT
Modalities
text, image → text
License
Proprietary

OpenAI's July 2026 flagship reasoning tier, tuned for hard STEM and agentic work; ChatGPT's top API SKU in the 5.6 family. Promotional Standard rates are $4/$20 (through at least Nov 21, 2026). Fast mode (2× price) delivers up to 2.5× Standard speed, and the Cerebras-powered Ultrafast preview reaches up to 750 tok/s.

Benchmark charts

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

Reasoning & knowledge

GPQA: B +12.4HLE: B +21.2CritPt: B +23.0AA-LCR: B +7.3Omniscience Acc.: B +33.7MMMU-Pro: B +18.0IFBench: A +3.2

Coding

SWE-Pro: B +12.2TermBench: B +27.3SciCode: B +9.9

Tool use & function calling

τ³-Banking: B +16.9

Arena

Arena Elo: B +81

Composite indices

AA Index: B +30.1AA Index v4.3: B +25.9

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