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Model comparison

DeepSeek V4 Pro vs GPT-5.5

DeepSeek against OpenAI, compared on context, price, and verified benchmark results.

Catalog record checked September 3, 2026Individual provider fields may changeEvidence confidence: High — see receipts below

DeepSeek

DeepSeek V4 Pro

Frontier · Open weights

vs

OpenAI

GPT-5.5

Frontier

AI model capability comparison
SpecificationDeepSeek V4 ProGPT-5.5
ProviderDeepSeekOpenAI
TierFrontierFrontier
Context window1MWinner: 1.05M
Max outputWinner: 384K128K
Input / 1M tokensWinner: $1.32$5
Output / 1M tokensWinner: $3.96$30
WeightsOpenClosed
Parameters1.6T total / 49B active (MoE)Not disclosedUnverified
Reasoning levelslow, high, maxnone, low, medium, high, xhigh, max
Modalitiestexttext, image
LicenseMITNot disclosedUnverified
API model iddeepseek-v4-progpt-5.5
ReleasedApril 24, 2026April 23, 2026
Artificial Analysis Intelligence Index (2026-08-14)53Not verifiedUnverified
Artificial Analysis Intelligence Index [xhigh] (2026-08-14)Not verifiedUnverified58
SWE-bench Verified (2026-04-24)80.6Winner: 82.6
GPQA Diamond (2026-04-24)90.1Winner: 93.5
Humanity's Last Exam (2026-04-24)48.2Winner: 52.2
MMLU-Pro (2026-04-24)87.5Not verifiedUnverified
Terminal-Bench 2.1 (2026-07-27)Not verifiedUnverified83.4

Prices are USD per million tokens at standard rates, excluding batch and caching discounts. Bold indicates the better figure where one is objectively better. Values we could not confirm from the provider are shown as “Not verified” rather than estimated.

Benchmark receipts

  • 2026-09-01: vals.ai SWE-bench Verified leaderboard (independent, mini-swe-agent bash-only); official SWE-bench not publishedReal GitHub issue resolution: does the model's patch pass the hidden tests. Comparability: comparable with caveat — Post-audit vendor claims and pre-audit scores sit on different task trust levels; scaffolding (agent harness, compute budget) also dominates results. Never aggregate across scaffolds.
  • 2026-08-14: Artificial AnalysisComposite index blending reasoning, knowledge, and coding evals into one 0–100 score. Comparability: directly comparable — AA occasionally rebaselines the index scale between snapshots — a score captured on one date is only comparable to same-snapshot scores (check measuredAt).
  • 2026-07-27: Kimi K3 model card (vendor-reported, xhigh); announcement charts show 93.6 — minor conflict preservedAgentic terminal work: multi-step tasks executed in a sandboxed shell environment. Comparability: comparable with caveat — Scores across Terminal-Bench major versions (v1 vs v2) are NOT comparable; harness configuration (container, time limits) also shifts results.
  • 2026-04-24: DeepSeek V4 Pro HF model card (vendor, Think Max, exact match)Real GitHub issue resolution: does the model's patch pass the hidden tests. Comparability: comparable with caveat — Post-audit vendor claims and pre-audit scores sit on different task trust levels; scaffolding (agent harness, compute budget) also dominates results. Never aggregate across scaffolds.
  • 2026-04-23: OpenAI — Introducing GPT-5.5 (vendor, with tools; 41.4 no tools)Frontier-knowledge ceiling: extremely hard multi-domain questions written to be near-impossible without deep expertise. Comparability: comparable with caveat — Subset/tool configurations (text-only vs with-tools) differ between vendors and materially change scores; must match configuration to compare.

Pricing tiers: DeepSeek V4 Pro: Official peak rates $1.32/$3.96 per MTok; off-peak $0.66/$1.98 (cache-miss). Open weights (MIT). 1.6T/49B active MoE. · GPT-5.5: Standard $5/$30 per MTok; >272K input billed 2x in / 1.5x out. Cached input $0.50/MTok; batch $2.50/$15.

FrontierOpen weightsRecord checked September 3, 2026

DeepSeek V4 Pro

DeepSeek V4 Pro is the open-weight (MIT) flagship with a 1M-token context at a fraction of frontier API cost.

Best for

  • Cost-sensitive hosted agents
  • Open-weight deployments
  • High-volume coding

Watch out

Self-hosting needs datacentre VRAM; hosted rates vary by provider. Price single-source — verify.

FrontierRecord checked September 3, 2026

GPT-5.5

GPT-5.5 is OpenAI's previous flagship — strong on Terminal-Bench 2.0 (82.7%) and 1M-token context.

Best for

  • Reasoning
  • Agentic coding
  • Long-context work

Watch out

Superseded by GPT-5.6 Sol on quality; still a capable, widely integrated model.

When the cheaper one wins

DeepSeek V4 Pro is cheaper on output at $3.96 per million tokens against $30 for GPT-5.5 — about 7.6×. Use the cheaper tier for classification, extraction, summarisation, and any task where the expensive model’s extra score does not change the accepted output. The expensive one only pays if your hardest task actually fails on the cheap tier. These are standard-tier API rates, excluding batch and cache discounts.

Run the model picker

Evidence confidence: High

How strong and complete the evidence behind this comparison is — not a prediction of which model is better.

  • Pricing verified on both sides — Input and output rates are verified for both models.
  • 4/5 core specs verified on both sides — Not published for at least one side: parameter count.
  • 4 shared named benchmarks with differing scores — Measured on: Artificial Analysis Intelligence Index, SWE-bench Verified, GPQA Diamond, Humanity's Last Exam.
  • Verified within the last 90 days — Newest catalog check was 8 days ago.
  • Both models carry source citations — Each side has at least two catalog sources on record.

Source receipts

Each catalog figure was checked against the provider or an independent second source on the date shown.

Related comparisons

Diving deeper on one model? DeepSeek V4 Pro · GPT-5.5

Common questions

DeepSeek V4 Pro vs GPT-5.5

Answered from the verified figures on this page rather than general guidance.

Is DeepSeek V4 Pro or GPT-5.5 cheaper for input?

DeepSeek V4 Pro is cheaper at $1.32 per million input tokens, against $5 for GPT-5.5 — roughly 3.8× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; DeepSeek V4 Pro has tiered pricing: Official peak rates $1.32/$3.96 per MTok; off-peak $0.66/$1.98 (cache-miss). Open weights (MIT). 1.6T/49B active MoE. GPT-5.5 has tiered pricing: Standard $5/$30 per MTok; >272K input billed 2x in / 1.5x out. Cached input $0.50/MTok; batch $2.50/$15.

Is DeepSeek V4 Pro or GPT-5.5 cheaper for output?

DeepSeek V4 Pro is cheaper at $3.96 per million output tokens, against $30 for GPT-5.5 — roughly 7.6× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; DeepSeek V4 Pro has tiered pricing: Official peak rates $1.32/$3.96 per MTok; off-peak $0.66/$1.98 (cache-miss). Open weights (MIT). 1.6T/49B active MoE. GPT-5.5 has tiered pricing: Standard $5/$30 per MTok; >272K input billed 2x in / 1.5x out. Cached input $0.50/MTok; batch $2.50/$15.

Which has the larger context window, DeepSeek V4 Pro or GPT-5.5?

GPT-5.5 accepts 1.05M tokens against 1M for DeepSeek V4 Pro. This only matters if you routinely send very long documents or large codebases.

Do DeepSeek V4 Pro and GPT-5.5 support the same reasoning levels?

DeepSeek V4 Pro exposes low, high, max, while GPT-5.5 exposes none, low, medium, high, xhigh, max.

Should I use DeepSeek V4 Pro or GPT-5.5?

Both sit in the frontier tier, so the choice usually comes down to price and context rather than capability. DeepSeek V4 Pro suits cost-sensitive hosted agents; GPT-5.5 suits reasoning.

Can I self-host DeepSeek V4 Pro or GPT-5.5?

DeepSeek V4 Pro publishes open weights, but self-hosting and third-party provider access depend on the licence, hardware, serving support, and availability. GPT-5.5 is a closed model whose supported access paths are controlled by its provider.

Next step

Choosing between them

The verified figures that separate this pair, computed from the catalog rather than restated boilerplate.

  • Input price: DeepSeek V4 Pro costs $1.32 per 1M tokens versus $5 for GPT-5.5 — a 3.8x difference at the headline tier.
  • Context: GPT-5.5 takes 1.05M against 1M for DeepSeek V4 Pro — only decisive if your prompts approach the smaller window.
  • Measured capability: GPT-5.5 leads Artificial Analysis Intelligence Index 58 to 53 (measured 2026-08-14).
  • Deployment: DeepSeek V4 Pro publishes weights you can self-host; the other is API-only.
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