Doubao Seed 2.1 Pro vs GPT-5.6 Terra
Doubao Seed 2.1 Pro wins on Overall, Coding, Multimodal. Every numeric field is compared below, with a worked monthly-cost example and a pick rule for each use case.
Verdict at a glance
Choose Doubao Seed 2.1 Pro if you…
- World-leading video understanding
- Excellent Chinese
- Strong agent ability
- Full 256K context
- Best for: Video understanding, Chinese tasks, AI agents
Choose GPT-5.6 Terra if you…
- OpenAI quality
- Halved price
- Rich ecosystem
- Best for: Value, General tasks, OpenAI ecosystem
Head-to-head aggregate scores
Scores are 0–100, aggregated from public benchmark information and independently weighted across three leaderboards. Rank is out of 22 tracked models.
Aggregated from public sources and independently weighted; methodology on the Terms page. Scores within 3 points are treated as statistically tied.
Specs & pricing — every field side by side
List API prices in USD per 1M tokens. The highlighted cell is the stronger value/capability on that row.
| Dimension | Doubao Seed 2.1 Pro | GPT-5.6 Terra | Verdict |
|---|---|---|---|
| Vendor | ByteDance (CN) | OpenAI (US) | Different vendors |
| Released | 2026.06 | 2026.07 | GPT-5.6 Terra is newer |
| Overall (rank) | 78 · #7 | 62 · #21 | Doubao Seed 2.1 Pro +16 |
| Coding | 76 · #7 | 70 · #12 | Doubao Seed 2.1 Pro +6 |
| Multimodal | 92 · #2 | 69 · #19 | Doubao Seed 2.1 Pro +23 |
| Context window | 256K | 1.05M | GPT-5.6 Terra larger |
| Max output | 256K | 128K | Doubao Seed 2.1 Pro longer |
| Effective-context | 93 | 88 | Doubao Seed 2.1 Pro more reliable |
| Input $/1M | $0.83 | $2.5 | Doubao Seed 2.1 Pro cheaper |
| Output $/1M | $4.17 | $15 | Doubao Seed 2.1 Pro cheaper |
| Cache discount | custom | 50% off | GPT-5.6 Terra deeper |
| Speed | ~65 tok/s | ~60 tok/s | Doubao Seed 2.1 Pro faster |
| TTFT | 0.5s | 0.5s | Tie |
| Function calling | 85 | 90 | GPT-5.6 Terra ahead |
| Refusal rate | ~11% | ~13% | Doubao Seed 2.1 Pro less restrictive |
| English | 72 | 88 | GPT-5.6 Terra |
| Chinese | 95 | 72 | Doubao Seed 2.1 Pro |
| Modalities | text, image, video | text, image | different coverage |
| Open weights | No | No | Both closed |
| Fine-tuning | Yes | No | |
| Free tier | Doubao App free; free quota on the Ark platform | No free API | |
| SOC2 / no-train | no / yes | yes / yes | |
| Private deployment | Yes | No | Doubao Seed 2.1 Pro |
Fields drawn from vendor public documentation and the Modelspectra 22-model dataset; speed varies with network, concurrency and prompt length. Verify current pricing before purchase.
Dimension-by-dimension analysis
Reasoning & overall intelligence
Doubao Seed 2.1 Pro leads the overall aggregate by 16 points (78 vs 62). That is a meaningful, not marginal, edge on hard, multi-step reasoning, while GPT-5.6 Terra remains a strong generalist that is not out of its depth on routine work.
Agentic coding
This is a modest gap: Doubao Seed 2.1 Pro scores 76 against 70. On multi-file edits, SWE-style tickets and long-horizon agent loops Doubao Seed 2.1 Pro needs fewer correction turns; GPT-5.6 Terra is still competent for scripts and assisted completion but trails as task complexity rises.
Multimodal
Doubao Seed 2.1 Pro leads multimodal 92 vs 69. A concrete modality difference: Doubao Seed 2.1 Pro additionally handles video.
Speed & latency
Doubao Seed 2.1 Pro is faster in interactive use: ~65 tok/s with 0.5s TTFT versus ~60 tok/s with 0.5s TTFT (about 1.1× the throughput). For conversational UIs where perceived responsiveness drives retention, that edge is a real product factor even when raw reasoning is lower.
Context: window vs usable recall
Nominal windows are 256K for Doubao Seed 2.1 Pro and 1.05M for GPT-5.6 Terra. Crucially, the larger nominal window does not win on usable recall: GPT-5.6 Terra advertises 1.05M but Doubao Seed 2.1 Pro scores higher on effective-context (93 vs 88), i.e. it actually retains more of what it was given.
Price & total cost
Doubao Seed 2.1 Pro is the cheaper API at $0.83/$4.17 versus GPT-5.6 Terra at $2.5/$15 per 1M input/output tokens — list input is about 3.0× lower. Cache discounts (GPT-5.6 Terra 50%) shift the effective bill, worked out below.
Chinese vs English
English: Doubao Seed 2.1 Pro 72 vs GPT-5.6 Terra 88. Chinese: 95 vs 72. For Chinese-language production, Doubao Seed 2.1 Pro is the stronger pick. Note that non-Chinese models generally require overseas network access for their APIs.
Tool use & ecosystem
Function-calling score: Doubao Seed 2.1 Pro 85 vs GPT-5.6 Terra 90, so GPT-5.6 Terra has the edge on structured tool use. Fine-tuning is available from Doubao Seed 2.1 Pro. Factor in existing SDK/plugin familiarity — switching cost often outweighs a few-point tool-use gap.
Cost worked example — same workload, real token math
Assume a production workload of 100M input + 30M output tokens per month, with 90% of input tokens served from cache. Figures use public list prices.
| Scenario · per month | Doubao Seed 2.1 Pro | GPT-5.6 Terra | Gap |
|---|---|---|---|
| List priceno cache applied | $208100M in × $0.83 + 30M out × $4.17 | $700100M in × $2.5 + 30M out × $15 | 3.37×gap |
| With caching90% of inputs cache-hit | $208no published cache discount | $58890M cached in × $1.25 + 10M in × $2.5 + 30M out × $15 | 2.83×gap |
Illustrative model; your input/output mix and cache-hit ratio change the result. Prices are list rates before any enterprise agreement.