Step 5 Preview vs Laguna S 2.1 vs LongCat-2.5-Preview
Laguna S 2.1 comes out ahead, 69 to 57 and 52 on our weighted score, and it is the cheaper option too.
StepFunStep 5 Preview
57/100- ECI—
- Price$1.00 / $2.70
- Context1M
- Our pick
PoolsideLaguna S 2.1
69/100- ECI—
- Price$0.10 / $0.20
- Context1.05M
Meituan (LongCat)LongCat-2.5-Preview
52/100- ECI—
- Price$0.75 / $2.95
- Context1M
Laguna S 2.1 is our pick
Laguna S 2.1 is the better all-round choice, scoring 69/100 against Step 5 Preview (57) and LongCat-2.5-Preview (52). It leads on price. Step 5 Preview wins on inputs & features. 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 priceLaguna S 2.1Laguna S 2.1 $0.125 · LongCat-2.5-Preview $1.30 · Step 5 Preview $1.43 per 1M tokens (3:1 blend)
- Longest contextLaguna S 2.1Laguna S 2.1 1,048,576 · Step 5 Preview 1,000,000 · LongCat-2.5-Preview 1,000,000 tokens
- Widest inputsStep 5 PreviewStep 5 Preview: Text, Images, Video · Laguna S 2.1: Text · LongCat-2.5-Preview: Text, Images
- Self-hostingLaguna S 2.1Publishes downloadable weights
| Measure | Weight | Step 5 Preview | Laguna S 2.1 | LongCat-2.5-Preview |
|---|---|---|---|---|
| Price | 50% | 43 | 93 | 44 |
| Inputs & features | 30% | 80 | 35 | 60 |
| Context window | 20% | 60 | 61 | 60 |
| Overall | 100% | 57/100 | 69/100 | 52/100 |
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 | Step 5 PreviewStepFun | Laguna S 2.1Poolside | LongCat-2.5-PreviewMeituan (LongCat) |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | — | — | — |
| ECI rank | — | — | — |
| Price per million tokens | |||
| Input | $1.00 | $0.10 (best) | $0.75 |
| Output | $2.70 | $0.20 (best) | $2.95 |
| Cached input | $0.05 | — | — |
| Blended (3:1) | $1.43 | $0.125 (best) | $1.30 |
| Long-context rate | Same rate | Same rate | Same rate |
| Price source | Official StepFun (Global) API | Median of 4 providers | Median of 1 providers |
| Limits | |||
| Context window | 1,000,000 tokens | 1,048,576 tokens (best) | 1,000,000 tokens |
| Max output | 1,000,000 tokens (best) | 32,768 tokens | 131,072 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | No | Yes |
| PDFs | No | No | No |
| Audio | No | No | No |
| Video | Yes | No | No |
| Reasoning | Yeslow · medium · high | Yes | Yes |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | No | No |
| Availability | |||
| Weights | Proprietary | Open | Proprietary |
| API model ID | step-5-preview | poolside/laguna-s-2.1 | — |
| API providers | 7 (best) | 6 | 2 |
| Released | Sep 16, 2026 | Jul 21, 2026 | Sep 25, 2026 |
| Knowledge cutoff | — | — | — |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- Step 5 Preview$15.40
- Laguna S 2.1$1.40
- LongCat-2.5-Preview$13.40
Which should you choose?
Which is better: Step 5 Preview, Laguna S 2.1 or LongCat-2.5-Preview?
Laguna S 2.1 is the better all-round choice, scoring 69/100 against Step 5 Preview (57) and LongCat-2.5-Preview (52). It leads on price. Step 5 Preview wins on inputs & features. 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, Step 5 Preview, Laguna S 2.1 or LongCat-2.5-Preview?
Laguna S 2.1 is cheaper at $0.10 input / $0.20 output per million tokens (median across 4 API providers; free on Poolside). LongCat-2.5-Preview costs $0.75 input / $2.95 output per million tokens (median across 1 API provider); Step 5 Preview costs $1.00 input / $2.70 output per million tokens (official StepFun (Global) API price). At a typical mix of three input tokens to one output token, that is $0.125 per million tokens for Laguna S 2.1 versus $1.30 for LongCat-2.5-Preview (10× as much) and $1.43 for Step 5 Preview (11× as much).
Which scores higher on benchmarks?
There is no independent benchmark that covers all three models yet. Step 5 Preview has not been scored yet, Laguna S 2.1 has not been scored yet and LongCat-2.5-Preview has not been scored yet.
Which is better for coding?
There are no published SWE-bench Verified results for Step 5 Preview, Laguna S 2.1 and LongCat-2.5-Preview 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 1,000,000 for Step 5 Preview and 1,000,000 for LongCat-2.5-Preview. Maximum output per response: Step 5 Preview up to 1,000,000, Laguna S 2.1 up to 32,768, LongCat-2.5-Preview up to 131,072 tokens.
Which can read images, PDFs, audio or video?
Step 5 Preview accepts text, images and video; Laguna S 2.1 accepts text; LongCat-2.5-Preview accepts text and images. Step 5 Preview handles the widest range of inputs.
Are any of these open source?
Laguna S 2.1 publishes its weights and can be self-hosted; Step 5 Preview and LongCat-2.5-Preview is proprietary.
Which is newer?
LongCat-2.5-Preview is the newest, released Sep 25, 2026. Step 5 Preview came out Sep 16, 2026; Laguna S 2.1 came out Jul 21, 2026.
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.
