# DeepSeek V4 Flash vs GPT-5.5 Pro

> GPT-5.5 Pro is the stronger model overall, scoring 64.3 to 53.6 on the Noometry Index. DeepSeek V4 Flash costs 257× less per token, which makes it the better buy when GPT-5.5 Pro's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/deepseek-v4-flash-vs-gpt-5-5-pro
- Last updated: 2026-10-10
- Shared benchmarks: 12

## Summary

- They share 12 benchmarks with published results for both. DeepSeek V4 Flash scores higher in 0 categories and GPT-5.5 Pro in 3 categories; 3 gaps are clear of the uncertainty.
- The widest gap is in math, where GPT-5.5 Pro leads 83.8 to 60.0.
- The biggest single-benchmark swing is FrontierMath Tier 4: 24.4% for DeepSeek V4 Flash and 78% for GPT-5.5 Pro.
- DeepSeek V4 Flash is cheaper at $0.15 / $0.60 per million input/output tokens, against $30 / $180 for GPT-5.5 Pro.
- GPT-5.5 Pro accepts more context: 1.05M tokens versus 1M.
- DeepSeek V4 Flash has downloadable open weights; the other is API-only.

## Snapshot

| | DeepSeek V4 Flash | GPT-5.5 Pro |
|---|---|---|
| Provider | DeepSeek | OpenAI |
| Noometry Index | 53.6 | 64.3 |
| Rank | 32 | 7 |
| Context | 1M | 1.05M |
| Input $/M | $0.15 | $30 |
| Output $/M | $0.60 | $180 |
| Weights | Open | Proprietary |

## Coding

- DeepSeek V4 Flash: 47.6 (#56)
- GPT-5.5 Pro: —

| Benchmark | DeepSeek V4 Flash | GPT-5.5 Pro |
|---|---|---|
| FrontierCode | 18.8% | — |
| LMArena WebDev | 1581 | — |
| SciCode | 49.9% | — |
| WeirdML | 63% | — |
| LMArena Coding | 1457 | — |
| ALE-Bench | 1,306 | — |

## Reasoning

- DeepSeek V4 Flash: 53.7 (#25)
- GPT-5.5 Pro: 73.6 (#7)

| Benchmark | DeepSeek V4 Flash | GPT-5.5 Pro |
|---|---|---|
| ARC-AGI-2 | 61.4% | 84.6% |
| SimpleBench | 61.1% | 76.9% |
| ARC-AGI-1 | 89% | 96.5% |
| CritPt | 16.6% | 30.6% |
| Chess Puzzles | 33% | 64% |
| DTBench | 90.9% | 96% |
| LMCA | 41.7% | 53.9% |
| Epoch Capabilities Index | 154.51 | 162.45 |
| Kagi LLM Benchmark | 52.2% | — |
| NYT Connections (extended) | 89.6% | — |
| LMArena Hard Prompts | 1443 | — |
| Mystery Game Puzzles | 34% | — |

## Math

- DeepSeek V4 Flash: 60.0 (#31)
- GPT-5.5 Pro: 83.8 (#8)

| Benchmark | DeepSeek V4 Flash | GPT-5.5 Pro |
|---|---|---|
| FrontierMath (Tiers 1-3) | 57.5% | 87.7% |
| FrontierMath Tier 4 | 24.4% | 78% |
| OTIS Mock AIME 2024-2025 | 94.4% | 100% |
| MathArena Final-Answer Competitions | 76.5% | — |
| ProofBench | 56% | — |
| LMArena Math | 1427 | — |
| FrontierMath (Feb 2025 set) | — | 52.4% |
| FrontierMath Tier 4 (v1) | — | 39.6% |

## Knowledge

- DeepSeek V4 Flash: 55.5 (#43)
- GPT-5.5 Pro: 64.2 (#17)

| Benchmark | DeepSeek V4 Flash | GPT-5.5 Pro |
|---|---|---|
| GPQA Diamond | 91% | 93.9% |
| SimpleQA Verified | 33.6% | — |
| LMArena Expert | 1441 | — |

## Multilingual

- DeepSeek V4 Flash: 53.2 (#71)
- GPT-5.5 Pro: —

| Benchmark | DeepSeek V4 Flash | GPT-5.5 Pro |
|---|---|---|
| LMArena Non-English | 1420 | — |
| LMArena Chinese | 1467 | — |
| LMArena French | 1438 | — |
| LMArena German | 1418 | — |
| LMArena Japanese | 1403 | — |
| LMArena Korean | 1383 | — |
| LMArena Russian | 1428 | — |
| LMArena Spanish | 1437 | — |

## Instruction Following

- DeepSeek V4 Flash: 75.1 (#76)
- GPT-5.5 Pro: —

| Benchmark | DeepSeek V4 Flash | GPT-5.5 Pro |
|---|---|---|
| LMArena Instruction Following | 1421 | — |

## Long Context

- DeepSeek V4 Flash: 43.8 (#81)
- GPT-5.5 Pro: —

| Benchmark | DeepSeek V4 Flash | GPT-5.5 Pro |
|---|---|---|
| LMArena Longer Query | 1435 | — |

## Writing & Preference

- DeepSeek V4 Flash: 64.0 (#59)
- GPT-5.5 Pro: —

| Benchmark | DeepSeek V4 Flash | GPT-5.5 Pro |
|---|---|---|
| LMArena Text | 1432 | — |
| LMArena Creative Writing | 1403 | — |
| EQ-Bench Creative Writing | 1559 | — |
| LMArena Multi-Turn | 1449 | — |

## FAQ

### Is DeepSeek V4 Flash better than GPT-5.5 Pro?

GPT-5.5 Pro is the stronger model overall, scoring 64.3 to 53.6 on the Noometry Index. DeepSeek V4 Flash costs 257× less per token, which makes it the better buy when GPT-5.5 Pro's lead doesn't matter for your workload.

### Which is cheaper, DeepSeek V4 Flash or GPT-5.5 Pro?

DeepSeek V4 Flash is cheaper. It lists at $0.15 per million input tokens and $0.60 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 1M.

### How many benchmarks do DeepSeek V4 Flash and GPT-5.5 Pro share?

12 benchmarks have published results for both models. DeepSeek V4 Flash has 41 scored results on Noometry and GPT-5.5 Pro has 14.