Mercury 2.5 vs Laguna S 2.1 vs Laguna XS 2.1
Too close to call on our weighted score (Mercury 2.5 71, Laguna S 2.1 69, Laguna XS 2.1 68). The right pick depends on what you value most.
InceptionMercury 2.5
71/100- ECI—
- Price$0.04 / $0.15
- Context260K
PoolsideLaguna S 2.1
69/100- ECI—
- Price$0.10 / $0.20
- Context1.05M
- Poolside
Laguna XS 2.1
68/100- ECI—
- Price$0.06 / $0.12
- Context262K
Too close to call
It is close. Our weighted score puts them within 2 points (Mercury 2.5 71/100, Laguna S 2.1 69/100, Laguna XS 2.1 68/100), so choose by what matters most for your work: Mercury 2.5 on price and Laguna S 2.1 for long inputs. 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 2.5Mercury 2.5 $0.068 · Laguna XS 2.1 $0.075 · Laguna S 2.1 $0.125 per 1M tokens (3:1 blend)
- Longest contextLaguna S 2.1Laguna S 2.1 1,048,576 · Laguna XS 2.1 262,144 · Mercury 2.5 260,000 tokens
- Widest inputsSame inputsMercury 2.5: Text · Laguna S 2.1: Text · Laguna XS 2.1: Text
- Self-hostingLaguna S 2.1 and Laguna XS 2.1Publishes downloadable weights
| Measure | Weight | Mercury 2.5 | Laguna S 2.1 | Laguna XS 2.1 |
|---|---|---|---|---|
| Price | 50% | 100 | 93 | 100 |
| Inputs & features | 30% | 45 | 35 | 35 |
| Context window | 20% | 36 | 61 | 37 |
| Overall | 100% | 71/100 | 69/100 | 68/100 |
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 2.5Inception | Laguna S 2.1Poolside | Laguna XS 2.1Poolside |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | — | — | — |
| ECI rank | — | — | — |
| Price per million tokens | |||
| Input | $0.04 (best) | $0.10 | $0.06 |
| Output | $0.15 | $0.20 | $0.12 (best) |
| Cached input | $0.004 | — | — |
| Blended (3:1) | $0.068 (best) | $0.125 | $0.075 |
| Long-context rate | Same rate | Same rate | Same rate |
| Price source | Official Inception API | Median of 4 providers | Median of 1 providers |
| Limits | |||
| Context window | 260,000 tokens | 1,048,576 tokens (best) | 262,144 tokens |
| Max output | 65,536 tokens (best) | 32,768 tokens | 32,768 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | No | No | No |
| PDFs | No | No | No |
| Audio | No | No | No |
| Video | No | No | No |
| Reasoning | Yeslow · medium · high | Yes | Yes |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | No | No |
| Availability | |||
| Weights | Proprietary | Open | Open |
| API model ID | mercury-2.5 | poolside/laguna-s-2.1 | poolside/laguna-xs-2.1 |
| API providers | 1 | 6 (best) | 4 |
| Released | Sep 8, 2026 | Jul 21, 2026 | Jul 2, 2026 |
| Knowledge cutoff | Nov 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 2.5$0.70
- Laguna S 2.1$1.40
- Laguna XS 2.1$0.84
Which should you choose?
Which is better: Mercury 2.5, Laguna S 2.1 or Laguna XS 2.1?
It is close. Our weighted score puts them within 2 points (Mercury 2.5 71/100, Laguna S 2.1 69/100, Laguna XS 2.1 68/100), so choose by what matters most for your work: Mercury 2.5 on price and Laguna S 2.1 for long inputs. 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 2.5, Laguna S 2.1 or Laguna XS 2.1?
Mercury 2.5 is cheaper at $0.04 input / $0.15 output per million tokens (official Inception API price). Laguna XS 2.1 costs $0.06 input / $0.12 output per million tokens (median across 1 API provider; free on Poolside); Laguna S 2.1 costs $0.10 input / $0.20 output per million tokens (median across 4 API providers; free on Poolside). At a typical mix of three input tokens to one output token, that is $0.068 per million tokens for Mercury 2.5 versus $0.075 for Laguna XS 2.1 (1.1× as much) and $0.125 for Laguna S 2.1 (1.9× as much).
Which scores higher on benchmarks?
There is no independent benchmark that covers all three models yet. Mercury 2.5 has not been scored yet, Laguna S 2.1 has not been scored yet and Laguna XS 2.1 has not been scored yet.
Which is better for coding?
There are no published SWE-bench Verified results for Mercury 2.5, Laguna S 2.1 and Laguna XS 2.1 yet, so there is no like-for-like coding score. Test both on a sample of your own tasks. All three support tool calling for agent workflows.
Which has the bigger context window?
Laguna S 2.1 has the largest context window at 1,048,576 tokens, against 262,144 for Laguna XS 2.1 and 260,000 for Mercury 2.5. Maximum output per response: Mercury 2.5 up to 65,536, Laguna S 2.1 up to 32,768, Laguna XS 2.1 up to 32,768 tokens.
Which can read images, PDFs, audio or video?
Mercury 2.5 accepts text; Laguna S 2.1 accepts text; Laguna XS 2.1 accepts text. They handle the same number of input types.
Are any of these open source?
Laguna S 2.1 and Laguna XS 2.1 publishes its weights and can be self-hosted; Mercury 2.5 is proprietary.
Which is newer?
Mercury 2.5 is the newest, released Sep 8, 2026. Laguna S 2.1 came out Jul 21, 2026; Laguna XS 2.1 came out Jul 2, 2026. Knowledge cutoff: Mercury 2.5 Nov 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.
