DeepSeek V4 Pro vs Gemini 3.5 Flash
DeepSeek V4 Pro (2026) and Gemini 3.5 Flash (2026) are frontier-tier reasoning models from DeepSeek and Google DeepMind. DeepSeek V4 Pro ships a 1m-token context window, while Gemini 3.5 Flash ships a 1.05m-token context window. On SWE-bench Verified, DeepSeek V4 Pro leads by 2.6 pts. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
DeepSeek V4 Pro is ~245% cheaper at $0.43/1M; pay for Gemini 3.5 Flash only for coding workflow support.
Decision scorecard
Local evidence first| Signal | DeepSeek V4 Pro | Gemini 3.5 Flash |
|---|---|---|
| Best for | reasoning-heavy apps, tool-calling agents, and long-context analysis | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1m | 1.05m |
| Cheapest output | $0.87/1M tokens | $9/1M tokens |
| Provider routes | 6 tracked | 4 tracked |
| Shared benchmarks | SWE-bench Verified leader | 8 shared |
Decision tradeoffs
- DeepSeek V4 Pro holds a shared-benchmark lead on SWE-bench Verified, ahead by 2.6 points.
- DeepSeek V4 Pro has the lower cheapest tracked output price at $0.87/1M tokens.
- DeepSeek V4 Pro has broader tracked provider coverage for fallback and route flexibility.
- Local decision data tags DeepSeek V4 Pro for Coding, RAG, and Agents.
- Gemini 3.5 Flash holds a shared-benchmark lead on Google-Proof Q&A, ahead by 2.1 points.
- Gemini 3.5 Flash has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Gemini 3.5 Flash uniquely exposes Vision, Multimodal, and Code execution in local model data.
- Local decision data tags Gemini 3.5 Flash for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
DeepSeek V4 Pro
$566
Cheapest tracked route/tier: DeepSeek Platform
Gemini 3.5 Flash
$3,450
Cheapest tracked route/tier: Google AI Studio
Estimated monthly gap: $2,885. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on Vercel AI Gateway and OpenRouter; start route-level A/B tests there.
- Gemini 3.5 Flash is $8.13/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Gemini 3.5 Flash adds Vision, Multimodal, and Code execution in local capability data.
- Provider overlap exists on OpenRouter and Vercel AI Gateway; start route-level A/B tests there.
- DeepSeek V4 Pro is $8.13/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Vision, Multimodal, and Code execution before moving production traffic.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-04-24 | 2026-05-19 |
| Context window | 1m | 1.05m |
| Parameters | 1.6T | — |
| Architecture | Mixture of Experts | Decoder Only |
| License | MITOSI-approved | Proprietary |
| Openness | Open source | Proprietary |
| Weights | Available | Not released |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: permitted | Commercial use: conditional |
| Knowledge cutoff | - | 2025-01 |
Pricing and availability
| Pricing attribute | DeepSeek V4 Pro | Gemini 3.5 Flash |
|---|---|---|
| Input price | $0.43/1M tokens | $1.50/1M tokens |
| Output price | $0.87/1M tokens | $9/1M tokens |
| Providers |
Capabilities
| Capability | DeepSeek V4 Pro | Gemini 3.5 Flash |
|---|---|---|
| Vision | No | Yes |
| Multimodal | No | Yes |
| Reasoning | Yes | Yes |
| JSON / Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | No | Yes |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | DeepSeek V4 Pro | Gemini 3.5 Flash |
|---|---|---|
| SWE-bench Verified | 80.6 | 78.0 |
| SWE-bench Pro | 55.4 | 55.1 |
| Google-Proof Q&A | 90.1 | 92.2 |
| Humanity's Last Exam | 37.7 | 40.2 |
| HumanEval | 76.8 | 92.0 |
| Terminal-Bench 2.0 | 59.1 | 76.2 |
| MCP-Atlas | 69.4 | 83.6 |
| GeneBench-Pro | 2.4 | 8.1 |
Continue comparing
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Last reviewed: 2026-09-24. Data sourced from public model cards and provider documentation.