Model comparison

DeepSeek-V3.1-Terminus vs GPT-5.5 Pro

GPT-5.5 Pro is the stronger model overall, scoring 64.3 to 43.1 on the Noometry Index. DeepSeek-V3.1-Terminus costs 149× less per token, which makes it the better buy when GPT-5.5 Pro's lead doesn't matter for your workload.

Last verified October 10, 2026. 3 shared benchmarks.

DeepSeek-V3.1-Terminus

DeepSeek

43.1

Rank #97 Confirmed

GPT-5.5 Pro OpenAI

64.3

Rank #8 Confirmed

Summary

They share 3 benchmarks with published results for both. DeepSeek-V3.1-Terminus scores higher in 0 categories and GPT-5.5 Pro in 2 categories; 2 gaps are clear of the uncertainty.
The widest gap is in reasoning, where GPT-5.5 Pro leads 73.3 to 26.4.
The biggest single-benchmark swing is CritPt: 1.7% for DeepSeek-V3.1-Terminus and 30.6% for GPT-5.5 Pro.
DeepSeek-V3.1-Terminus is cheaper at $0.27 / $1 per million input/output tokens, against $30 / $180 for GPT-5.5 Pro.
GPT-5.5 Pro accepts more context: 1.05M tokens versus 164K.
DeepSeek-V3.1-Terminus has downloadable open weights; the other is API-only.

Side by side

DeepSeek-V3.1-Terminus and GPT-5.5 Pro specifications
	DeepSeek-V3.1-Terminus	GPT-5.5 Pro
Provider	DeepSeek	OpenAI
Noometry Index	43.1	64.3
Released	2025-09-22	2026-04-23
Weights	Open	Proprietary
Context window	164K	1.05M
Max output	147K	128K
Input $ / M tokens	$0.27	$30
Output $ / M tokens	$1	$180
Results tracked	16	14

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Category by category

Coding Not comparable

DeepSeek-V3.1-Terminus: 42.0 (#113), GPT-5.5 Pro: —

Coding benchmarks
Benchmark	DeepSeek-V3.1-Terminus	GPT-5.5 Pro
SciCode	40.6%	—
LMArena Coding	1426	—
ALE-Bench	745.17	—

Reasoning GPT-5.5 Pro leads

DeepSeek-V3.1-Terminus: 26.4 (#133), GPT-5.5 Pro: 73.3 (#10)

Reasoning benchmarks
Benchmark	DeepSeek-V3.1-Terminus	GPT-5.5 Pro
CritPt	1.7%	30.6%
DTBench	81.3%	96%
LMCA	28.6%	53.9%
ARC-AGI-2	—	84.6%
SimpleBench	—	76.9%
Kagi LLM Benchmark	57.4%	—
ARC-AGI-1	—	96.5%
Chess Puzzles	—	64%
LMArena Hard Prompts	1426	—
Epoch Capabilities Index	—	162.07

Math GPT-5.5 Pro leads

DeepSeek-V3.1-Terminus: 38.5 (#137), GPT-5.5 Pro: 84.0 (#10)

Math benchmarks
Benchmark	DeepSeek-V3.1-Terminus	GPT-5.5 Pro
FrontierMath (Tiers 1-3)	—	87.7%
FrontierMath Tier 4	—	78%
OTIS Mock AIME 2024-2025	—	100%
LMArena Math	1402	—
FrontierMath (Feb 2025 set)	—	52.4%
FrontierMath Tier 4 (v1)	—	39.6%

Knowledge Not comparable

DeepSeek-V3.1-Terminus: —, GPT-5.5 Pro: 64.1 (#19)

Knowledge benchmarks
Benchmark	DeepSeek-V3.1-Terminus	GPT-5.5 Pro
GPQA Diamond	—	93.9%

Multilingual Not comparable

DeepSeek-V3.1-Terminus: 52.1 (#92), GPT-5.5 Pro: —

Multilingual benchmarks
Benchmark	DeepSeek-V3.1-Terminus	GPT-5.5 Pro
LMArena Non-English	1407	—
LMArena Russian	1436	—

Instruction Following Not comparable

DeepSeek-V3.1-Terminus: 74.0 (#106), GPT-5.5 Pro: —

Instruction Following benchmarks
Benchmark	DeepSeek-V3.1-Terminus	GPT-5.5 Pro
LMArena Instruction Following	1404	—

Long Context Not comparable

DeepSeek-V3.1-Terminus: 43.4 (#97), GPT-5.5 Pro: —

Long Context benchmarks
Benchmark	DeepSeek-V3.1-Terminus	GPT-5.5 Pro
LMArena Longer Query	1421	—

Writing & Preference Not comparable

DeepSeek-V3.1-Terminus: 61.0 (#92), GPT-5.5 Pro: —

Writing & Preference benchmarks
Benchmark	DeepSeek-V3.1-Terminus	GPT-5.5 Pro
LMArena Text	1419	—
LMArena Creative Writing	1403	—
LMArena Multi-Turn	1411	—

Frequently asked questions

Is DeepSeek-V3.1-Terminus better than GPT-5.5 Pro?

Which is cheaper, DeepSeek-V3.1-Terminus or GPT-5.5 Pro?

DeepSeek-V3.1-Terminus is cheaper. It lists at $0.27 per million input tokens and $1 per million output tokens; GPT-5.5 Pro lists at $30 and $180.

Which has the bigger context window?

GPT-5.5 Pro does, with 1.05M tokens against 164K.

How many benchmarks do DeepSeek-V3.1-Terminus and GPT-5.5 Pro share?

3 benchmarks have published results for both models. DeepSeek-V3.1-Terminus has 16 scored results on Noometry and GPT-5.5 Pro has 14.