LLM Reference

DeepSeek V3.1 vs Gemini 2.5 Flash

DeepSeek V3.1 (2025) and Gemini 2.5 Flash (2025) are compact production models from DeepSeek and Google DeepMind. DeepSeek V3.1 ships a 64k-token context window, while Gemini 2.5 Flash ships a 1m-token context window. On MMLU PRO, Gemini 2.5 Flash leads by 5.1 pts. On pricing, DeepSeek V3.1 costs $0.27/1M input tokens versus $0.30/1M for the alternative. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.

Pick Gemini 2.5 Flash for general evaluation; DeepSeek V3.1 is better when coding workflow support matters more.

Decision scorecard

Local evidence first
SignalDeepSeek V3.1Gemini 2.5 Flash
Best formultimodal apps and provider-routed productionmultimodal apps, tool-calling agents, and long-context analysis
Decision fitCoding, Agents, and VisionCoding, RAG, and Agents
Context window64k1m
Cheapest output$1/1M tokens$2.50/1M tokens
Provider routes8 tracked6 tracked
Shared benchmarks1 sharedMMLU PRO leader

Decision tradeoffs

Choose DeepSeek V3.1 when...
  • DeepSeek V3.1 has the lower cheapest tracked output price at $1/1M tokens.
  • DeepSeek V3.1 has broader tracked provider coverage for fallback and route flexibility.
  • Local decision data tags DeepSeek V3.1 for Coding, Agents, and Vision.
Choose Gemini 2.5 Flash when...
  • Gemini 2.5 Flash holds a shared-benchmark lead on MMLU PRO, ahead by 5.1 points.
  • Gemini 2.5 Flash has the larger context window for long prompts, retrieval packs, or transcript analysis.
  • Gemini 2.5 Flash uniquely exposes JSON / Tool use in local model data.
  • Local decision data tags Gemini 2.5 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.

Lower estimate DeepSeek V3.1

DeepSeek V3.1

$466

Cheapest tracked route/tier: Novita AI

Gemini 2.5 Flash

$865

Cheapest tracked route/tier: Google AI Studio

Estimated monthly gap: $399. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.

Switch friction

DeepSeek V3.1 -> Gemini 2.5 Flash
  • Provider overlap exists on Replicate API and Vercel AI Gateway; start route-level A/B tests there.
  • Gemini 2.5 Flash is $1.50/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
  • Gemini 2.5 Flash adds JSON / Tool use in local capability data.
Gemini 2.5 Flash -> DeepSeek V3.1
  • Provider overlap exists on Replicate API and Vercel AI Gateway; start route-level A/B tests there.
  • DeepSeek V3.1 is $1.50/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
  • Check replacement coverage for JSON / Tool use before moving production traffic.

Specs

Specification
Released2025-08-212025-06-17
Context window64k1m
Parameters671B total, 37B active (MoE)—
ArchitectureMixture of ExpertsDecoder Only
LicenseMITOSI-approvedProprietary
OpennessOpen sourceProprietary
WeightsUnknownNot released
CodeUnknownUnknown
Commercial useCommercial use: permittedCommercial use: conditional
Knowledge cutoff-2025-01

Pricing and availability

Pricing attributeDeepSeek V3.1Gemini 2.5 Flash
Input price$0.27/1M tokens$0.30/1M tokens
Output price$1/1M tokens$2.50/1M tokens
Providers
Microsoft FoundryFireworks AINVIDIA NIMTogether AIAWS BedrockReplicate API
Google AI StudioGCP Vertex AIReplicate APIOpenRouterVercel AI GatewayInceptron

Capabilities

CapabilityDeepSeek V3.1Gemini 2.5 Flash
VisionYesYes
MultimodalYesYes
ReasoningNoNo
JSON / Tool useNoYes
Structured outputsYesYes
Code executionYesYes
IDE integrationNoNo
Computer useNoNo
Parallel agentsNoNo

Benchmarks

BenchmarkDeepSeek V3.1Gemini 2.5 Flash
MMLU PRO83.388.4

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Last reviewed: 2026-06-29. Data sourced from public model cards and provider documentation.