AI Models · Open-Source vs Paid

Phi 4 Open vs INMercury 2.5 Paid

Phi 4 vs Mercury 2.5 compared — price per token, context window, multimodality, openness and which to choose. Can the open-source model replace the paid one? Full 2026 breakdown.

Prices & specs refreshed from live data · olud.ai

Open-model prices = cheapest provider via OpenRouter; official maker rates may be higher.

Phi 4OpenMicrosoft
$0.07 /M input
$0.14 /M outputNo per-token fees if you self-host
TypeOpen-weight
Context window16K tokens
MultimodalNo
Self-hostYes
INMercury 2.5PaidInception
$0.04 /M input
$0.15 /M outputManaged API (no infra to run)
TypeProprietary
Context window260K tokens
MultimodalNo
Self-hostNo
Choose Phi 4 if you want to self-host, keep your data private and skip per-token fees — it's open-weight and runs on your own hardware. Choose Mercury 2.5 if you want frontier capability through a managed API with zero infrastructure to run.

Phi 4 vs Mercury 2.5 specs

SpecPhi 4Mercury 2.5Winner
MakerMicrosoftInception
TypeOpen-weightProprietaryPhi 4
Context window16K tokens260K tokensINMercury 2.5
Input price$0.07/M · free self-host$0.04/MINMercury 2.5
Output price$0.14/M · free self-host$0.15/MPhi 4
Vision / multimodalNoNo
Tool / function callingNoYesINMercury 2.5
Self-hostableYesNo (API only)Phi 4
LicenseMITProprietaryPhi 4

Price gap & when to choose each

Choose Phi 4 if…
  • You want to self-host or run on your cloud
  • You prioritize data privacy & control
  • You want the lowest operating costs
  • You are building open or reproducible AI
INChoose Mercury 2.5 if…
  • You want frontier performance through a managed API
  • You need the longer 260K context window
  • You value reliability & ecosystem
  • You don't want to manage infrastructure

Feature comparison

CapabilityPhi 4Mercury 2.5
Open weights (downloadable)
Self-hostable
Runs fully offline
Vision / multimodal
Tool / function calling
1M+ context window

Benchmarks: Phi 4 vs Mercury 2.5

Independent benchmark scores measured by Artificial Analysis. Higher is better (except latency).

Phi 4
Mercury 2.5
Intelligence index
5.9
Math index
18
GPQA
57.5%
MMLU-Pro
71.4%
Humanity's Last Exam
3.8%
Long Context Reasoning
0%
LiveCodeBench
23.1%
MATH-500
81%
AIME
14.3%
AIME 2025
18%
IFBench
23.5%
τ²-Bench
0%
Terminal-Bench Hard
3.8%
Speed
43.7 tok/s
Latency
0.95s
Intelligence per $
26.9

Benchmark data by Artificial Analysis.

How Phi 4 and Mercury 2.5 score

🏆 Best value & openness: Phi 4 (3.8 vs 3.0 / 5)
CriterionPhi 4Mercury 2.5
Cost-efficiency5.05.0
Context window2.04.0
Openness5.01.5
Self-hosting5.01.0
Multimodality2.03.5

Scores come from live data — output price (cost), context length, open vs closed weights (openness & self-hosting) and vision/tool support (multimodality). Raw task quality isn't scored here; it depends on your benchmark — see the verdict.

What each model is

Phi 4 Open

Microsoft · Open-weight

[Microsoft Research](/microsoft) Phi-4 is designed to perform well in complex reasoning tasks and can operate efficiently in situations with limited memory or where quick responses are needed. At 14 billion...

Mercury 2.5 Paid

Inception · Proprietary

Mercury 2.5 is the fastest reasoning LLM, and the latest diffusion LLM (dLLM) from Inception. Instead of generating tokens sequentially, Mercury 2.5 produces and refines multiple tokens in parallel, achieving...

Frequently asked questions

Is Phi 4 as good as Mercury 2.5?

Phi 4 is open-weight and competitive on many tasks, but Mercury 2.5 may still lead on the hardest reasoning and agentic work. The gap keeps narrowing — benchmark both on your actual use case before deciding.

Can I run Phi 4 locally?

Yes. Phi 4 has open weights, so you can self-host it on your own GPUs or run it via a low-cost API. Mercury 2.5 is API-only and cannot be self-hosted.

Phi 4 vs Mercury 2.5 — which should I pick in 2026?

Choose Phi 4 if you want to self-host, keep your data private and skip per-token fees — it's open-weight and runs on your own hardware. Choose Mercury 2.5 if you want frontier capability through a managed API with zero infrastructure to run.

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