GPT-5.3 Chat vs Mercury 2
Mercury 2 comes out ahead, 52 to 28 on our weighted score, and it is the cheaper option too.
OpenAIGPT-5.3 Chat
28/100- ECI—
- Price$1.75 / $14.00
- Context128K
- Our pick
InceptionMercury 2
52/100- ECI—
- Price$0.25 / $0.75
- Context128K
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Make it a three-way comparison.
Mercury 2 is our pick
Mercury 2 is the better all-round choice, scoring 52/100 against GPT-5.3 Chat (28). It leads on price. GPT-5.3 Chat 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 priceMercury 2Mercury 2 $0.375 · GPT-5.3 Chat $4.81 per 1M tokens (3:1 blend)
- Longest contextAbout the sameGPT-5.3 Chat 128,000 · Mercury 2 128,000 tokens
- Widest inputsGPT-5.3 ChatGPT-5.3 Chat: Text, Images · Mercury 2: Text
- Self-hostingNo open weightsBoth are available only through APIs
| Measure | Weight | GPT-5.3 Chat | Mercury 2 |
|---|---|---|---|
| Price | 50% | 17 | 67 |
| Inputs & features | 30% | 50 | 45 |
| Context window | 20% | 24 | 24 |
| Overall | 100% | 28/100 | 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 | GPT-5.3 ChatOpenAI | Mercury 2Inception |
|---|---|---|
| Capability | ||
| Capabilities Index (ECI) | — | — |
| ECI rank | — | — |
| Price per million tokens | ||
| Input | $1.75 | $0.25 (best) |
| Output | $14.00 | $0.75 (best) |
| Cached input | — | $0.025 |
| Blended (3:1) | $4.81 | $0.375 (best) |
| Long-context rate | Same rate | Same rate |
| Price source | Median of 4 providers | Official Inception API |
| Limits | ||
| Context window | 128,000 tokens | 128,000 tokens |
| Max output | 16,384 tokens | 50,000 tokens (best) |
| Inputs and features | ||
| Text | Yes | Yes |
| Images | Yes | No |
| PDFs | No | No |
| Audio | No | No |
| Video | No | No |
| Reasoning | No | Yeslow · medium · high |
| Tool calling | Yes | Yes |
| Structured output | No | Yes |
| Availability | ||
| Weights | Proprietary | Proprietary |
| API model ID | — | mercury-2 |
| API providers | 4 | 7 (best) |
| Released | Mar 3, 2026 | Feb 24, 2026 |
| Knowledge cutoff | Aug 31, 2025 | — |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- GPT-5.3 Chat$45.50
- Mercury 2$4.00
Which should you choose?
Which is better: GPT-5.3 Chat or Mercury 2?
Mercury 2 is the better all-round choice, scoring 52/100 against GPT-5.3 Chat (28). It leads on price. GPT-5.3 Chat 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, GPT-5.3 Chat or Mercury 2?
Mercury 2 is cheaper at $0.25 input / $0.75 output per million tokens (official Inception API price). GPT-5.3 Chat costs $1.75 input / $14.00 output per million tokens (median across 4 API providers). At a typical mix of three input tokens to one output token, that is $0.375 per million tokens for Mercury 2 versus $4.81 for GPT-5.3 Chat (13× as much).
Which scores higher on benchmarks?
There is no independent benchmark that covers both models yet. GPT-5.3 Chat has not been scored yet and Mercury 2 has not been scored yet.
Which is better for coding?
There are no published SWE-bench Verified results for GPT-5.3 Chat and Mercury 2 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?
GPT-5.3 Chat and Mercury 2 share the same 128,000-token context window. Maximum output per response: GPT-5.3 Chat up to 16,384, Mercury 2 up to 50,000 tokens.
Which can read images, PDFs, audio or video?
GPT-5.3 Chat accepts text and images; Mercury 2 accepts text. GPT-5.3 Chat handles the widest range of inputs.
Are any of these open source?
No. GPT-5.3 Chat and Mercury 2 are proprietary and only available through APIs and apps.
Which is newer?
GPT-5.3 Chat is the newest, released Mar 3, 2026. Mercury 2 came out Feb 24, 2026. Knowledge cutoff: GPT-5.3 Chat Aug 31, 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 Nov 2, 2026.
