Step 2 (16K) vs Sonar Reasoning Pro
Sonar Reasoning Pro comes out ahead, 27 to 11 on our weighted score, and it is the cheaper option too.
StepFunStep 2 (16K)
11/100- ECI—
- Price$5.21 / $16.44
- Context16K
- Our pick
PerplexitySonar Reasoning Pro
27/100- ECI—
- Price$2.00 / $8.00
- Context128K
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Make it a three-way comparison.
Sonar Reasoning Pro is our pick
Sonar Reasoning Pro is the better all-round choice, scoring 27/100 against Step 2 (16K) (11). It leads on price, 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 priceSonar Reasoning ProSonar Reasoning Pro $3.50 · Step 2 (16K) $8.02 per 1M tokens (3:1 blend)
- Longest contextSonar Reasoning ProSonar Reasoning Pro 128,000 · Step 2 (16K) 16,384 tokens
- Widest inputsSonar Reasoning ProStep 2 (16K): Text · Sonar Reasoning Pro: Text, Images
- Self-hostingNo open weightsBoth are available only through APIs
| Measure | Weight | Step 2 (16K) | Sonar Reasoning Pro |
|---|---|---|---|
| Price | 50% | 7 | 24 |
| Inputs & features | 30% | 25 | 35 |
| Context window | 20% | 0 | 24 |
| Overall | 100% | 11/100 | 27/100 |
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 2 (16K)StepFun | Sonar Reasoning ProPerplexity |
|---|---|---|
| Capability | ||
| Capabilities Index (ECI) | — | — |
| ECI rank | — | — |
| Price per million tokens | ||
| Input | $5.21 | $2.00 (best) |
| Output | $16.44 | $8.00 (best) |
| Cached input | $1.04 | — |
| Blended (3:1) | $8.02 | $3.50 (best) |
| Long-context rate | Same rate | Same rate |
| Price source | Official StepFun (Global) API | Official Perplexity API |
| Limits | ||
| Context window | 16,384 tokens | 128,000 tokens (best) |
| Max output | 8,192 tokens (best) | 4,096 tokens |
| Inputs and features | ||
| Text | Yes | Yes |
| Images | No | Yes |
| PDFs | No | No |
| Audio | No | No |
| Video | No | No |
| Reasoning | No | Yesminimal · low · medium · high |
| Tool calling | Yes | No |
| Structured output | No | No |
| Availability | ||
| Weights | Proprietary | Proprietary |
| API model ID | step-2-16k | sonar-reasoning-pro |
| API providers | 1 | 4 (best) |
| Released | Jan 1, 2025 | Jan 1, 2024 |
| Knowledge cutoff | Jun 2024 | Sep 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.
- Step 2 (16K)$84.98
- Sonar Reasoning Pro$36.00
Which should you choose?
Which is better: Step 2 (16K) or Sonar Reasoning Pro?
Sonar Reasoning Pro is the better all-round choice, scoring 27/100 against Step 2 (16K) (11). It leads on price, 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, Step 2 (16K) or Sonar Reasoning Pro?
Sonar Reasoning Pro is cheaper at $2.00 input / $8.00 output per million tokens (official Perplexity API price). Step 2 (16K) costs $5.21 input / $16.44 output per million tokens (official StepFun (Global) API price). At a typical mix of three input tokens to one output token, that is $3.50 per million tokens for Sonar Reasoning Pro versus $8.02 for Step 2 (16K) (2.3× as much).
Which scores higher on benchmarks?
There is no independent benchmark that covers both models yet. Step 2 (16K) has not been scored yet and Sonar Reasoning Pro has not been scored yet.
Which is better for coding?
There are no published SWE-bench Verified results for Step 2 (16K) and Sonar Reasoning Pro yet, so there is no like-for-like coding score. Test both on a sample of your own tasks. Note that Sonar Reasoning Pro does not support tool calling, which most coding agents need.
Which has the bigger context window?
Sonar Reasoning Pro has the largest context window at 128,000 tokens, against 16,384 for Step 2 (16K). Maximum output per response: Step 2 (16K) up to 8,192, Sonar Reasoning Pro up to 4,096 tokens.
Which can read images, PDFs, audio or video?
Step 2 (16K) accepts text; Sonar Reasoning Pro accepts text and images. Sonar Reasoning Pro handles the widest range of inputs.
Are any of these open source?
No. Step 2 (16K) and Sonar Reasoning Pro are proprietary and only available through APIs and apps.
Which is newer?
Step 2 (16K) is the newest, released Jan 1, 2025. Sonar Reasoning Pro came out Jan 1, 2024. Knowledge cutoff: Step 2 (16K) Jun 2024, Sonar Reasoning Pro Sep 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.
