Which is cheaper, DeepSeek V3.5 or GPT-5 mini?

DeepSeek V3.5 is cheaper at the input + output rate combined: $0.420 versus $2.25 per million tokens.

Which has higher quality, DeepSeek V3.5 or GPT-5 mini?

GPT-5 mini has the higher AA Intelligence Index score: 84 versus 81.

Can I switch between DeepSeek V3.5 and GPT-5 mini via one API?

Both DeepSeek V3.5 and GPT-5 mini are accessible through OpenRouter's unified gateway, which lets you switch models with one API key. Phase 2 of AIpricly will add scenario-routed automatic primary + fallback chains.

DeepSeek V3.5 vs GPT-5 mini

Side-by-side pricing, capabilities, real-world cost across common scenarios, and our editorial pick.

Add a modelUp to 4 models can be compared

all prices in USD per 1M tokens

DeepSeek V3.5

DeepSeek · released 2025-12-01

Quality (AA Index)81

Input price$0.14

Output price$0.28

Context128K

Throughput95 tok/s

P50 latency1.5s

View full pricing

OVERALL WINNER

GPT-5 mini

OpenAI · released 2026-01-15

Quality (AA Index)84

Input price$0.25

Output price$2.00

Context400K

Throughput280 tok/s

P50 latency0.3s

View full pricing

Try DeepSeek V3.5 on OpenRouter Try GPT-5 mini on OpenRouter

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Head-to-head specs

Green column = winner per metric

Metric	DeepSeek V3.5	GPT-5 mini	Verdict
Input price /1M tokens	$0.14	$0.25	DeepSeek V3.5 −44%
Output price /1M tokens	$0.28	$2.00	DeepSeek V3.5 −86%
Context window max input length	128K	400K	GPT-5 mini +3.1×
AA Quality AA Intelligence Index (0–100)	81	84	GPT-5 mini +3pt
Arena Elo LMArena human-pref Elo (800–2000)	—	—	Tied
Throughput tokens per second	95	280	GPT-5 mini +195%
P50 latency first token	1.5s	0.3s	GPT-5 mini −80%
Vision multimodal	—
Function calling tool use			Tied
Reasoning mode chain-of-thought	—

Monthly cost across common scenarios

Default usage assumptions

Scenario	DeepSeek V3.5	GPT-5 mini
customer support 1000K req · 600/180 tok	$134	$510
chat with docs 300K req · 4000/300 tok	$193	$480
code generation 500K req · 2000/500 tok	$210	$750
voice assistant 600K req · 800/200 tok	$101	$360

Our pick

For most workloads, choose GPT-5 mini.

3.1× the context window — better for long documents and agents
195% faster throughput — matters for streaming UX and voice agents

GPT-5 family inheritance at a fraction of the cost — strong on routine tasks but visibly weaker on multi-step reasoning. Default choice when GPT-5 is overkill.

Choose DeepSeek V3.5 instead if: Roughly GPT-4o-class quality at roughly 90% off. Tradeoff is region availability (Chinese provider) and slower output throughput than Western frontier tiers.

Read our deep analysis

The Cheapest LLM API for Production in 2026

Why pick? Use both with smart routing

Phase 2 · gateway with fallback chain

Set GPT-5 mini as primary, DeepSeek V3.5 as fallback. One key, one bill, automatic failover when GPT-5 mini errors.

PHASE 2 PREVIEW · gateway not live yetThis endpoint does not exist yet. The gateway is in Phase 2 — what you see below is a design preview of the planned interface, not a live API. We will email subscribers when it launches.

Preview the planned API call

$ curl https://api.aipricly.com/v1/chat/completions \
  -H "Authorization: Bearer $AIPC_KEY" \
  -d '{
    "routing": {
      "primary": "openai/gpt-5-mini",
      "fallback": ["deepseek/deepseek-v3-5"]
    },
    "messages": [{"role": "user", "content": "..."}]
  }'