# DeepSeek V4.1 Flash vs GPT-5.5 Pro

> GPT-5.5 Pro is the stronger model overall, scoring 64.3 to 52.8 on the Noometry Index. DeepSeek V4.1 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-v4-1-flash-vs-gpt-5-5-pro
- Last updated: 2026-10-12
- Shared benchmarks: 8

## Summary

- They share 8 benchmarks with published results for both. DeepSeek V4.1 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 reasoning, where GPT-5.5 Pro leads 73.3 to 50.2.
- The biggest single-benchmark swing is FrontierMath Tier 4: 26.8% for DeepSeek V4.1 Flash and 78% for GPT-5.5 Pro.
- DeepSeek V4.1 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 V4.1 Flash has downloadable open weights; the other is API-only.

## Snapshot

| | DeepSeek V4.1 Flash | GPT-5.5 Pro |
|---|---|---|
| Provider | DeepSeek | OpenAI |
| Noometry Index | 52.8 | 64.3 |
| Rank | 38 | 8 |
| Context | 1M | 1.05M |
| Input $/M | $0.15 | $30 |
| Output $/M | $0.60 | $180 |
| Weights | Open | Proprietary |

## Coding

- DeepSeek V4.1 Flash: 52.9 (#32)
- GPT-5.5 Pro: —

| Benchmark | DeepSeek V4.1 Flash | GPT-5.5 Pro |
|---|---|---|
| LMArena WebDev | 1619 | — |
| SciCode | 51.9% | — |
| LMArena Coding | 1506 | — |
| ALE-Bench | 1,092 | — |

## Agentic & Tool Use

- DeepSeek V4.1 Flash: 31.2 (#69)
- GPT-5.5 Pro: —

| Benchmark | DeepSeek V4.1 Flash | GPT-5.5 Pro |
|---|---|---|
| APEX-Agents | 39.5% | — |
| GDP.pdf | 19.8% | — |

## Reasoning

- DeepSeek V4.1 Flash: 50.2 (#36)
- GPT-5.5 Pro: 73.3 (#10)

| Benchmark | DeepSeek V4.1 Flash | GPT-5.5 Pro |
|---|---|---|
| CritPt | 14.3% | 30.6% |
| DTBench | 89.9% | 96% |
| LMCA | 47% | 53.9% |
| Epoch Capabilities Index | 154.9 | 162.07 |
| ARC-AGI-2 | — | 84.6% |
| SimpleBench | — | 76.9% |
| NYT Connections (extended) | 89.6% | — |
| ARC-AGI-1 | — | 96.5% |
| Chess Puzzles | — | 64% |
| LMArena Hard Prompts | 1483 | — |
| Mystery Game Puzzles | 43% | — |
| Surface Evolver Bench | 46.3% | — |

## Math

- DeepSeek V4.1 Flash: 66.7 (#25)
- GPT-5.5 Pro: 84.0 (#10)

| Benchmark | DeepSeek V4.1 Flash | GPT-5.5 Pro |
|---|---|---|
| FrontierMath (Tiers 1-3) | 67.4% | 87.7% |
| FrontierMath Tier 4 | 26.8% | 78% |
| OTIS Mock AIME 2024-2025 | 98.3% | 100% |
| ProofBench | 54% | — |
| LMArena Math | 1477 | — |
| FrontierMath (Feb 2025 set) | — | 52.4% |
| FrontierMath Tier 4 (v1) | — | 39.6% |

## Knowledge

- DeepSeek V4.1 Flash: 57.9 (#38)
- GPT-5.5 Pro: 64.1 (#19)

| Benchmark | DeepSeek V4.1 Flash | GPT-5.5 Pro |
|---|---|---|
| GPQA Diamond | 89.8% | 93.9% |
| LMArena Expert | 1506 | — |

## Multimodal

- DeepSeek V4.1 Flash: 39.1 (#61)
- GPT-5.5 Pro: —

| Benchmark | DeepSeek V4.1 Flash | GPT-5.5 Pro |
|---|---|---|
| LMArena Vision | 1277 | — |
| Furniture Assembly | 34.2% | — |

## Multilingual

- DeepSeek V4.1 Flash: 55.0 (#35)
- GPT-5.5 Pro: —

| Benchmark | DeepSeek V4.1 Flash | GPT-5.5 Pro |
|---|---|---|
| LMArena Non-English | 1448 | — |
| LMArena Chinese | 1497 | — |
| LMArena French | 1452 | — |
| LMArena German | 1484 | — |
| LMArena Japanese | 1412 | — |
| LMArena Korean | 1452 | — |
| LMArena Russian | 1471 | — |
| LMArena Spanish | 1459 | — |

## Instruction Following

- DeepSeek V4.1 Flash: 77.3 (#26)
- GPT-5.5 Pro: —

| Benchmark | DeepSeek V4.1 Flash | GPT-5.5 Pro |
|---|---|---|
| LMArena Instruction Following | 1474 | — |

## Long Context

- DeepSeek V4.1 Flash: 45.2 (#47)
- GPT-5.5 Pro: —

| Benchmark | DeepSeek V4.1 Flash | GPT-5.5 Pro |
|---|---|---|
| LMArena Longer Query | 1475 | — |

## Writing & Preference

- DeepSeek V4.1 Flash: 65.4 (#48)
- GPT-5.5 Pro: —

| Benchmark | DeepSeek V4.1 Flash | GPT-5.5 Pro |
|---|---|---|
| LMArena Text | 1462 | — |
| LMArena Creative Writing | 1435 | — |
| EQ-Bench Creative Writing | 1540 | — |
| LMArena Multi-Turn | 1457 | — |

## FAQ

### Is DeepSeek V4.1 Flash better than GPT-5.5 Pro?

GPT-5.5 Pro is the stronger model overall, scoring 64.3 to 52.8 on the Noometry Index. DeepSeek V4.1 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 V4.1 Flash or GPT-5.5 Pro?

DeepSeek V4.1 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 V4.1 Flash and GPT-5.5 Pro share?

8 benchmarks have published results for both models. DeepSeek V4.1 Flash has 37 scored results on Noometry and GPT-5.5 Pro has 14.