Mercury 2 vs Seed 1.8
Seed 1.8 comes out ahead, 63 to 53 on our weighted score.
Seed 1.8 is our pick
Seed 1.8 is the better all-round choice, scoring 63/100 against Mercury 2 (53). It leads on inputs & features and context window. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.
- CapabilityNot enough dataNo independent benchmark covers every model here yet
- Lowest priceMercury 2Mercury 2 $0.375 · Seed 1.8 $0.386 per 1M tokens (3:1 blend)
- Longest contextSeed 1.8Seed 1.8 256,000 · Mercury 2 128,000 tokens
- Widest inputsSeed 1.8Mercury 2: Text · Seed 1.8: Text, Images
- Self-hostingNo open weightsBoth are available only through APIs
| Measure | Weight | Mercury 2 | Seed 1.8 |
|---|---|---|---|
| Price | 50% | 70 | 69 |
| Inputs & features | 30% | 45 | 70 |
| Context window | 20% | 24 | 36 |
| Overall | 100% | 53/100 | 63/100 |
Left out because at least one model lacks the data: capability. The remaining weights were rescaled.
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification |  Mercury 2Inception |  Seed 1.8ByteDance Seed |
|---|---|---|
| Capability | ||
| Capabilities Index (ECI) | — | — |
| ECI rank | — | — |
| Price per million tokens | ||
| Input | $0.25 | $0.119 (best) |
| Output | $0.75 (best) | $1.19 |
| Cached input | $0.025 | $0.024 (best) |
| Blended (3:1) | $0.375 (best) | $0.386 |
| Long-context rate | Same rate | Over 32K: $0.178 / $2.37 |
| Price source | Official Inception API | Official Volcengine Ark API |
| Limits | ||
| Context window | 128,000 tokens | 256,000 tokens (best) |
| Max output | 50,000 tokens | 64,000 tokens (best) |
| Inputs and features | ||
| Text | Yes | Yes |
| Images | No | Yes |
| PDFs | No | No |
| Audio | No | No |
| Video | No | No |
| Reasoning | Yeslow · medium · high | Yesminimal · low · medium · high · xhigh · max |
| Tool calling | Yes | Yes |
| Structured output | Yes | Yes |
| Availability | ||
| Weights | Proprietary | Proprietary |
| API model ID | mercury-2 | doubao-seed-1-8-251228 |
| API providers | 1 | 2 (best) |
| Released | Feb 24, 2026 | Dec 28, 2025 |
| Knowledge cutoff | Jan 1, 2025 | — |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- Mercury 2$4.00
- Seed 1.8$3.56
Which should you choose?
Which is better: Mercury 2 or Seed 1.8?
Seed 1.8 is the better all-round choice, scoring 63/100 against Mercury 2 (53). It leads on inputs & features and context window. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.
Which is cheaper, Mercury 2 or Seed 1.8?
Mercury 2 is cheaper at $0.25 input / $0.75 output per million tokens (official Inception API price). Seed 1.8 costs $0.119 input / $1.19 output per million tokens (official Volcengine Ark API price). At a typical mix of three input tokens to one output token, that is $0.375 per million tokens for Mercury 2 versus $0.386 for Seed 1.8 (1× as much).
Which scores higher on benchmarks?
There is no independent benchmark that covers both models yet. Mercury 2 has not been scored yet and Seed 1.8 has not been scored yet.
Which is better for coding?
There are no published SWE-bench Verified results for Mercury 2 and Seed 1.8 yet, so there is no like-for-like coding score. Test both on a sample of your own tasks. Both support tool calling for agent workflows.
Which has the bigger context window?
Seed 1.8 has the largest context window at 256,000 tokens, against 128,000 for Mercury 2. Maximum output per response: Mercury 2 up to 50,000, Seed 1.8 up to 64,000 tokens.
Which can read images, PDFs, audio or video?
Mercury 2 accepts text; Seed 1.8 accepts text and images. Seed 1.8 handles the widest range of inputs.
Are any of these open source?
No. Mercury 2 and Seed 1.8 are proprietary and only available through APIs and apps.
Which is newer?
Mercury 2 is the newest, released Feb 24, 2026. Seed 1.8 came out Dec 28, 2025. Knowledge cutoff: Mercury 2 Jan 1, 2025.
How do you decide the winner?
Each model gets a 0–100 score on capability (50%, independent benchmark results); price (25%, blended price per million tokens (3 input : 1 output), log scale); inputs & features (15%, image, PDF, audio and video input, tool calling, structured output and reasoning); context window (10%, maximum tokens per request, log scale). Dimensions missing for any model are dropped and the remaining weights rescaled, so every model is judged on the same evidence. Specs and prices come from public model listings and the labs’ own API pages; capability scores come from independent benchmark runs. Data updated Oct 4, 2026.
