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Home / Compare / AI models / DeepSeek V4.1 Flash vs GPT-6 Luna

DeepSeek V4.1 Flash vs GPT-6 Luna

Official DeepSeek and OpenAI API prices and LMArena scores, checked 2026-10-29. Add up to 2 more models to compare 4.

Verdict

GPT-6 Luna costs less; DeepSeek V4.1 Flash wins more LMArena tasks.

GPT-6 Luna is 3x cheaper on input and 2.4x cheaper on output. DeepSeek V4.1 Flash scores 40 points higher for reasoning and math; GPT-6 Luna scores 1 point higher for agent tasks. Across 7 shared LMArena tasks, DeepSeek V4.1 Flash leads 4 to 1 (2 tied). A medium month (20M input + 5M output tokens) costs $12 on DeepSeek V4.1 Flash and $4.50 on GPT-6 Luna.

  • Pick DeepSeek V4.1 Flash if you care most about reasoning and math (+40), coding (+31) and chat (+17) or you reuse long prompts (cached input $0.006 vs $0.01).
  • Pick GPT-6 Luna if you want the lower bill ($4.50 vs $12 for a medium month).
Sample month

Medium: 20M input + 5M output tokens a month at list price (short-context rate, no caching or batch discounts).

DeepSeek V4.1 FlashvsGPT-6 Luna
Price per 1M tokens
Input$0.30$0.10 (better)
Cached input$0.006 (better)$0.01
Output$1.20$0.50 (better)
Sample month, medium$12$4.50 (better)
Context
Context window1M1.05M (better)
Quality (LMArena relative score, out of 100)
Coding46 (better)15
Chat17 (better)0
Creative writing00
Roleplay and characters00
Reasoning and math40 (better)0
Vision14 (better)0
Long documentsn/an/a
Cheap bulk and agents5051 (better)

Marked side is better: lower for prices, higher for context and scores. Bars are scaled to the larger of the two.

Spec
DeepSeek V4.1 Flash
GPT-6 Luna
Price per 1M tokens
Input$0.30$0.10
Cached input$0.006$0.01
Output$1.20$0.50
Blend 3:1$0.525$0.20
Sample month, medium$12$4.50
Context
Context window1M tokens1.05M tokens
Quality (LMArena, out of 100)
Coding46/100 #12 of 5015/100 #27 of 50
Chat17/100 #18 of 510/100 #40 of 51
Creative writing0/100 #22 of 510/100 #35 of 51
Roleplay and characters0/100 #24 of 510/100 #40 of 51
Reasoning and math40/100 #14 of 510/100 #36 of 51
Vision14/100 #19 of 330/100 #29 of 33
Long documentsNot rankedNot ranked
Cheap bulk and agents50/100 #16 of 3451/100 #15 of 34
Details
ProviderDeepSeekOpenAI
API model iddeepseek-flashgpt-6-luna
NotesPeak rate. Off-peak is half price.Prompts up to 272K.
Sources
Last checked2026-10-292026-10-29
Official pricingDeepSeek pricingOpenAI pricing

API prices in USD per 1M tokens from each provider's official pricing page. Blend 3:1 = (3 x input + output) / 4. Sample month = stated input and output tokens at the list price, no caching. Quality: relative score out of 100 on each LMArena leaderboard (100 = top model we price on that board, n/a = not ranked there), data licensed CC BY 4.0. See how we pick.

Where each one ranks on LMArena

Relative score out of 100 on each leaderboard (100 = the top model we price there), with the rank among the models from our API price table that appear on that board.

  • Coding (Code Arena): DeepSeek V4.1 Flash #12 of 50 (46/100), GPT-6 Luna #27 of 50 (15/100)
  • Chat (Text Arena): DeepSeek V4.1 Flash #18 of 51 (17/100), GPT-6 Luna #40 of 51 (0/100)
  • Creative writing (Text Arena creative writing): DeepSeek V4.1 Flash #22 of 51 (0/100), GPT-6 Luna #35 of 51 (0/100)
  • Roleplay and characters (Text Arena multi-turn): DeepSeek V4.1 Flash #24 of 51 (0/100), GPT-6 Luna #40 of 51 (0/100)
  • Reasoning and math (Text Arena math): DeepSeek V4.1 Flash #14 of 51 (40/100), GPT-6 Luna #36 of 51 (0/100)
  • Vision (Vision Arena): DeepSeek V4.1 Flash #19 of 33 (14/100), GPT-6 Luna #29 of 33 (0/100)
  • Long documents (Document Arena): DeepSeek V4.1 Flash not ranked, GPT-6 Luna not ranked
  • Cheap bulk and agents (Agent Arena): DeepSeek V4.1 Flash #16 of 34 (50/100), GPT-6 Luna #15 of 34 (51/100)

Pricing details from the official pages

DeepSeek V4.1 Flash lists $0.30 input, $1.20 output, $0.006 cached input per 1M tokens on DeepSeek pricing. GPT-6 Luna lists $0.10 input, $0.50 output, $0.01 cached input per 1M tokens on OpenAI pricing. Prices checked 2026-10-29.

  • DeepSeek V4.1 Flash: Peak rate. Off-peak is half price.
  • GPT-6 Luna: Prompts up to 272K.

Sample monthly bill at list price, no caching: Light (2M input + 0.5M output tokens): $1.20 vs $0.45. Medium (20M input + 5M output tokens): $12 vs $4.50. Heavy (200M input + 50M output tokens): $120 vs $45.

FAQ

Is DeepSeek V4.1 Flash cheaper than GPT-6 Luna?

DeepSeek V4.1 Flash costs $0.30 input and $1.20 output per 1M tokens; GPT-6 Luna costs $0.10 and $0.50. For a medium month (20M input + 5M output tokens) GPT-6 Luna is cheaper: $4.50 vs $12.

Which is better for coding, DeepSeek V4.1 Flash or GPT-6 Luna?

On LMArena's Code Arena DeepSeek V4.1 Flash scores 46/100 (#12 of 50) and GPT-6 Luna 15/100 (#27 of 50), so DeepSeek V4.1 Flash is ahead by 31 points.

Which has the bigger context window?

DeepSeek V4.1 Flash: 1M tokens. GPT-6 Luna: 1.05M tokens.

How much do DeepSeek V4.1 Flash and GPT-6 Luna cost per month?

Light (2M input + 0.5M output tokens): $1.20 vs $0.45. Medium (20M input + 5M output tokens): $12 vs $4.50. Heavy (200M input + 50M output tokens): $120 vs $45. Pick your own token counts in the plan vs API calculator.

Where do these numbers come from?

Prices come from each provider's official pricing page, checked daily. Quality is the relative score on the LMArena leaderboard dataset, licensed CC BY 4.0. Where a model is not ranked we show n/a.

Sources

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