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Model comparison

DeepSeek V4.1 Flash vs GPT-5.6 Terra

DeepSeek against OpenAI, compared on context, price, and verified benchmark results.

Catalog record checked September 26, 2026Individual provider fields may changeEvidence confidence: High — see receipts below

DeepSeek

DeepSeek V4.1 Flash

Balanced · Open weights

vs

OpenAI

GPT-5.6 Terra

Balanced

AI model capability comparison
SpecificationDeepSeek V4.1 FlashGPT-5.6 Terra
ProviderDeepSeekOpenAI
TierBalancedBalanced
Context window1MWinner: 1.05M
Max outputWinner: 384K128K
Input / 1M tokensWinner: $0.30$2
Output / 1M tokensWinner: $1.20$12
WeightsOpenClosed
Parameters552B MoE (causal encoder-decoder; 8B active for input, 16B for output)mid-tier reasoning model
Reasoning levelslow, high, maxnone, low, medium, high, xhigh, max
Modalitiestext, imagetext, image
LicenseMITNot disclosedUnverified
API model iddeepseek-flashgpt-5.6-terra
ReleasedSeptember 10, 2026July 9, 2026
Artificial Analysis Intelligence Index [max] (2026-09-26)39.5Winner: 42.1
DeepSWE 1.1 [max] (2026-09-10)74.2Not verifiedUnverified
Terminal-Bench 2.1 [max] (2026-09-10)90.6Not verifiedUnverified
Terminal-Bench 2.1 (2026-07-09)Not verifiedUnverified87.4
GPQA Diamond [max] (2026-09-10)90.9Not verifiedUnverified
SWE-bench Verified (2026-09-01)Not verifiedUnverified95.4
LiveBench (2026-09-05)Not verifiedUnverified77.9

Prices are USD per million tokens at standard rates, excluding batch and caching discounts. Bold indicates the better figure where one is objectively better. Values we could not confirm from the provider are shown as “Not verified” rather than estimated.

Benchmark receipts

Where each score comes from, and how far it can be compared across models.

  • 2026-09-26
    Artificial Analysis

    Composite index blending reasoning, knowledge, and coding evals into one 0–100 score.

    Comparable with caveatOnly same-version scores are comparable. v4.3.2 was rebaselined (the top score fell from 66 on v4.1.1 to ~58), so v4.1.1 figures must not be compared with v4.3.2 figures — check measuredAt.

  • 2026-09-10
    DeepSeek V4.1-Flash release notes (vendor)

    Agentic software engineering: pass@1 on real repo tasks with reported cost per completed task.

    Directly comparable

  • 2026-09-05
    LiveBench official leaderboard (benchmark-owned), max effort

    Contamination-resistant general capability across reasoning, coding, math, data analysis, and language, with monthly question refreshes.

    Comparable with caveatRolling question set: observations months apart measure different question mixes. Record the measurement date and compare within ~1 month windows.

  • 2026-09-01
    vals.ai SWE-bench Verified leaderboard (independent, mini-swe-agent bash-only) (independent; official SWE-bench not published)

    Real GitHub issue resolution: does the model's patch pass the hidden tests.

    Comparable with caveatPost-audit vendor claims and pre-audit scores sit on different task trust levels; scaffolding (agent harness, compute budget) also dominates results. Never aggregate across scaffolds.

  • 2026-07-09
    OpenAI GPT-5.6 announcement (vendor; chart transcribed by Vellum)

    Agentic terminal work: multi-step tasks executed in a sandboxed shell environment.

    Comparable with caveatNot comparable with Terminal-Bench 3.0 or 4.0 (different task sets) or v1; harness configuration (container, time limits) also shifts results.

Pricing tiers

DeepSeek V4.1 Flash: Official peak rates $0.30/$1.20 per MTok; off-peak $0.15/$0.60 (50% of peak). Cache hit $0.006 peak / $0.003 off-peak. Peak hours are weekdays 01:00–04:00 and 06:00–10:00 UTC. Open weights (MIT). The legacy deepseek-v4-flash and deepseek-v4-flash-vision-exp ids temporarily route here.

GPT-5.6 Terra: Launch list was $2.50/$15; cut to $2/$12 on 2026-07-30. Above 272K input the whole request bills 2x input / 1.5x output. Cached input $0.20/MTok; cache writes 1.25x input; batch $1/$6.

BalancedOpen weightsRecord checked September 26, 2026

DeepSeek V4.1 Flash

DeepSeek V4.1 Flash is DeepSeek's new default — an open-weight (MIT) multimodal MoE that DeepSeek says beats V4-Pro on performance, cost and speed.

Best for

  • Open-weight price-performance
  • High-volume hosted agents
  • Self-hosting with MIT weights

Watch out

Vendor benchmark claims are far ahead of its independent Artificial Analysis score (39.5 on v4.3.2); peak/off-peak billing means the hour you run matters.

BalancedRecord checked September 26, 2026

GPT-5.6 Terra

GPT-5.6 Terra delivers roughly GPT-5.5-class quality at about half the cost, with the full 1.05M-token context.

Best for

  • Cost-sensitive production
  • Mixed reasoning workloads
  • High-volume agents

Watch out

GPT-6 Sol ($2/$10) now costs less than Terra ($2/$12) and scores higher — route frontier work to GPT-6 Sol. Terra has no named successor and is still served.

When the cheaper one wins

DeepSeek V4.1 Flash is cheaper on output at $1.20 per million tokens against $12 for GPT-5.6 Terra — about 10×. Use the cheaper tier for classification, extraction, summarisation, and any task where the expensive model’s extra score does not change the accepted output. The expensive one only pays if your hardest task actually fails on the cheap tier. These are standard-tier API rates, excluding batch and cache discounts.

Run the model picker

Evidence confidence: High

How strong and complete the evidence behind this comparison is — not a prediction of which model is better.

  • Pricing verified on both sides — Input and output rates are verified for both models.
  • 5/5 core specs verified on both sides — All core specifications verified for both models.
  • 2 shared named benchmarks with differing scores — Measured on: Artificial Analysis Intelligence Index, Terminal-Bench 2.1.
  • Verified within the last 90 days — Newest catalog check was 2 days ago.
  • Both models carry source citations — Each side has at least two catalog sources on record.

Source receipts

Each catalog figure was checked against the provider or an independent second source on the date shown.

Related comparisons

Diving deeper on one model? DeepSeek V4.1 Flash · GPT-5.6 Terra

Common questions

DeepSeek V4.1 Flash vs GPT-5.6 Terra

Answered from the verified figures on this page rather than general guidance.

Is DeepSeek V4.1 Flash or GPT-5.6 Terra cheaper for input?
DeepSeek V4.1 Flash is cheaper at $0.30 per million input tokens, against $2 for GPT-5.6 Terra — roughly 6.7× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; DeepSeek V4.1 Flash has tiered pricing: Official peak rates $0.30/$1.20 per MTok; off-peak $0.15/$0.60 (50% of peak). Cache hit $0.006 peak / $0.003 off-peak. Peak hours are weekdays 01:00–04:00 and 06:00–10:00 UTC. Open weights (MIT). The legacy deepseek-v4-flash and deepseek-v4-flash-vision-exp ids temporarily route here. GPT-5.6 Terra has tiered pricing: Launch list was $2.50/$15; cut to $2/$12 on 2026-07-30. Above 272K input the whole request bills 2x input / 1.5x output. Cached input $0.20/MTok; cache writes 1.25x input; batch $1/$6.
Is DeepSeek V4.1 Flash or GPT-5.6 Terra cheaper for output?
DeepSeek V4.1 Flash is cheaper at $1.20 per million output tokens, against $12 for GPT-5.6 Terra — roughly 10× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; DeepSeek V4.1 Flash has tiered pricing: Official peak rates $0.30/$1.20 per MTok; off-peak $0.15/$0.60 (50% of peak). Cache hit $0.006 peak / $0.003 off-peak. Peak hours are weekdays 01:00–04:00 and 06:00–10:00 UTC. Open weights (MIT). The legacy deepseek-v4-flash and deepseek-v4-flash-vision-exp ids temporarily route here. GPT-5.6 Terra has tiered pricing: Launch list was $2.50/$15; cut to $2/$12 on 2026-07-30. Above 272K input the whole request bills 2x input / 1.5x output. Cached input $0.20/MTok; cache writes 1.25x input; batch $1/$6.
Which has the larger context window, DeepSeek V4.1 Flash or GPT-5.6 Terra?
GPT-5.6 Terra accepts 1.05M tokens against 1M for DeepSeek V4.1 Flash. This only matters if you routinely send very long documents or large codebases.
Do DeepSeek V4.1 Flash and GPT-5.6 Terra support the same reasoning levels?
DeepSeek V4.1 Flash exposes low, high, max, while GPT-5.6 Terra exposes none, low, medium, high, xhigh, max.
Should I use DeepSeek V4.1 Flash or GPT-5.6 Terra?
Both sit in the balanced tier, so the choice usually comes down to price and context rather than capability. DeepSeek V4.1 Flash suits open-weight price-performance; GPT-5.6 Terra suits cost-sensitive production.
Can I self-host DeepSeek V4.1 Flash or GPT-5.6 Terra?
DeepSeek V4.1 Flash publishes open weights, but self-hosting and third-party provider access depend on the licence, hardware, serving support, and availability. GPT-5.6 Terra is a closed model whose supported access paths are controlled by its provider.

Next step

Choosing between them

The verified figures that separate this pair, computed from the catalog rather than restated boilerplate.

  • Input price: DeepSeek V4.1 Flash costs $0.30 per 1M tokens versus $2 for GPT-5.6 Terra — a 6.7x difference at the headline tier.
  • Context: GPT-5.6 Terra takes 1.05M against 1M for DeepSeek V4.1 Flash — only decisive if your prompts approach the smaller window.
  • Measured capability: GPT-5.6 Terra leads Artificial Analysis Intelligence Index 42.1 to 39.5 (measured 2026-09-26).
  • Deployment: DeepSeek V4.1 Flash publishes weights you can self-host; the other is API-only.
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