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A · closed · GPT-5.x

GPT-5.4

OpenAI

B · closed · GPT-5.x

GPT-5.5

OpenAI

2:12

overall capability wins (2 ties across 16 scored). GPT-5.5 leads overall.

  • Reasoning0:7
  • Coding1:4
  • Arena0:1
  • Tool use1:0
  • Pricing3:0
  • Speed2:0

Verdict

GPT-5.5 leads coding (widest gap: +123.4 on WebDev Elo); GPT-5.5 ranks higher on LMArena (+10 Elo); GPT-5.4 is ~2.0x cheaper on a blended token basis than GPT-5.5.

  • GPT-5.5 leads coding (widest gap: +123.4 on WebDev Elo)
  • GPT-5.5 ranks higher on LMArena (+10 Elo)
  • GPT-5.4 is ~2.0x cheaper on a blended token basis than GPT-5.5

Cost for 1M in + 250K out

Illustrative chat workload at primary-provider list prices.

GPT-5.4
$6.25
GPT-5.5
$12.50

GPT-5.4 is about 2.0x 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 5, 2026

Apr 23, 2026

Knowledge cutoff

-

-

API / provider

OpenAI

OpenAI

Modalities

text, image → text

text, image → text

Specs

Context window

1.1M

1.1M

tie

Max output

128K

128K

tie

Parameters

—

—

—

Pricing

Input $/1M

$2.50

$5

A +$2.50

Output $/1M

$15

$30

A +$15

Blended $/1M (3∶1)

$5.63

$11.25

A +$5.63

Speed

tok/s

85

70

A +15

TTFT (s)

0.4

0.5

A +0.10

Reasoning

MMLU-Pro

—

—

—

GPQA Diamond

92.0

93.5

B +1.5 pts

Humanity's Last Exam

43.7

45.8

B +2.1 pts

AIME 2025

—

—

—

MATH-500

—

—

—

Humanity's Last Exam (with tools)

—

—

—

AA-Omniscience Accuracy

50.8

58.0

B +7.2 pts

AA-LCR v1.1

82.0

84.3

B +2.3 pts

CritPt

23.4

27.1

B +3.7 pts

MMMU-Pro

78.4

79.9

B +1.5 pts

IFBench

73.9

75.9

B +2.0 pts

Chartography

—

—

—

Chartography (With Tools)

—

—

—

Coding

SWE-bench Verified

—

—

—

SWE-bench Pro

57.7

58.6

B +0.9 pts

SWE-bench Multilingual

—

—

—

LiveCodeBench

—

—

—

Terminal-Bench 2.1

78.3

84.3

B +6.0 pts

Aider Polyglot

—

—

—

Terminal-Bench 3

—

—

—

BigCodeBench

—

—

—

SciCode

56.6

55.8

A +0.8 pts

CursorBench

—

58.4

—

SWE-Rebench

57.6

62.7

B +5.1 pts

NL2Repo-Bench

—

—

—

DeepSWE

—

67.0

—

WebDev Arena

1,387

1,510

B +123 Elo

Terminal-Bench 4.0

—

—

—

CursorBench 4.0

—

—

—

FrontierCode v1.1 (Main)

—

—

—

Arena

LMArena Elo

1,466

1,476

B +10 Elo

GPT-5.4

Context
1.1M / 128K out
Parameters
—
Price
$2.50 / $15
Speed
85 tok/s · 0.4s TTFT
Modalities
text, image → text
License
Proprietary

Solid mid-2026 OpenAI workhorse between GPT-5 and the 5.5/5.6 flagships.

GPT-5.5

Context
1.1M / 128K out
Parameters
—
Price
$5 / $30
Speed
70 tok/s · 0.5s TTFT
Modalities
text, image → text
License
Proprietary

Prior OpenAI flagship with strong coding and long context; still widely used alongside the newer 5.6 family.

Benchmark charts

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

Reasoning & knowledge

GPQA: B +1.5HLE: B +2.1CritPt: B +3.7AA-LCR: B +2.3Omniscience Acc.: B +7.2MMMU-Pro: B +1.5IFBench: B +2.0

Coding

SWE-Pro: B +0.9TermBench: B +6.0SciCode: A +0.8SWE-Rebench: B +5.1WebDev Elo: B +123

Tool use & function calling

τ³-Banking: A +0.6

Arena

Arena Elo: B +10

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