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Head-to-head comparison

Llama 3.1 8B Instruct vs Phi 4 reasoning vision 15B

Llama 3.1 8B Instruct (Meta) and Phi 4 reasoning vision 15B (Microsoft) compared on the ModelCap Index, API price, context window, provider availability, weight access and every public benchmark board they share. Figures are the same ones shown on the live rankings; nothing here is a hidden score.

Snapshot as of 15 September 2026

As of 15 September 2026, Phi 4 reasoning vision 15B holds the stronger ModelCap Index position (#191 vs #193); and Phi 4 reasoning vision 15B ships open weights.

Which should you choose?

Choose Llama 3.1 8B Instruct if…

  • you want provider choice — 5 listed API providers against 0.

Choose Phi 4 reasoning vision 15B if…

  • you want the stronger overall ModelCap Index position — #191 against #193 (10.0 vs 7.5 points).
  • you want to self-host: Phi 4 reasoning vision 15B ships open weights while Llama 3.1 8B Instruct is gated access.
  • you want the more recently listed model — Phi 4 reasoning vision 15B was listed 23 January 2026, Llama 3.1 8B Instruct 23 July 2024.

Llama 3.1 8B Instruct vs Phi 4 reasoning vision 15B: specs, pricing and context

Specification comparison of Llama 3.1 8B Instruct and Phi 4 reasoning vision 15B
FieldLlama 3.1 8B InstructMetaPhi 4 reasoning vision 15BMicrosoft
ModelCap Index position#193#191
Index score7.510.0
EvidenceMeasuredInherited
Input price / 1M tokens$0.05Unlisted
Output price / 1M tokens$0.08Unlisted
Context window131K tokens— tokens
Max output tokens118K—
API providers listed50
Weight accessGated accessOpen weights
Input modalitiesTextText, Image
First listed23 July 202423 January 2026
PublisherMetaMicrosoft

Evidence: 2 public benchmark observations across 2 boards · finetune of microsoft/Phi-4-reasoning · finetune (100%). Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.

Benchmark scores: Llama 3.1 8B Instruct vs Phi 4 reasoning vision 15B

Public benchmark boards where Llama 3.1 8B Instruct or Phi 4 reasoning vision 15B has a published result
BoardLlama 3.1 8B InstructPhi 4 reasoning vision 15BLeads
Arena codingArena (LMArena)12601252–1267—Only one result
BFCL V4UC Berkeley (Gorilla)25.8Prompt—Only one result

Scores are the sources' own published figures for each model's best evaluated configuration; ModelCap never re-runs a benchmark.

Want a different pairing? Open the interactive comparison tool to swap either model for any current ranked language model.

Llama 3.1 8B Instruct vs Phi 4 reasoning vision 15B: common questions

Is Llama 3.1 8B Instruct better than Phi 4 reasoning vision 15B?

Phi 4 reasoning vision 15B ranks higher on the ModelCap Index as of 15 September 2026: #191 against #193. That is a capability ranking built from public benchmark evidence with published uncertainty; whether it is "better" for you also depends on price, context and where you can run it. Their published uncertainty intervals overlap, so the rank difference alone does not establish a reliable capability advantage for your workload.

Is Llama 3.1 8B Instruct cheaper than Phi 4 reasoning vision 15B?

At least one of the two has no listed API price on ModelCap right now, so no price comparison is made.

Which has the bigger context window, Llama 3.1 8B Instruct or Phi 4 reasoning vision 15B?

Both publish a 131K-token context window.

Which is better for coding, Llama 3.1 8B Instruct or Phi 4 reasoning vision 15B?

The two models do not share a coding benchmark board on ModelCap yet, so no head-to-head coding score is published; the ModelCap Index position is the closest overall signal.

Are Llama 3.1 8B Instruct and Phi 4 reasoning vision 15B open-weight models?

Llama 3.1 8B Instruct: Gated access. Phi 4 reasoning vision 15B: Open weights. Open weights mean the checkpoint can be downloaded and self-hosted under its licence; API-only models are available solely through hosted endpoints.

Where can I run Llama 3.1 8B Instruct and Phi 4 reasoning vision 15B?

ModelCap currently lists 5 API providers for Llama 3.1 8B Instruct and 0 for Phi 4 reasoning vision 15B, from the OpenRouter catalogue snapshot the site serves; each model page lists the providers and their prices.

How current is this Llama 3.1 8B Instruct vs Phi 4 reasoning vision 15B comparison?

Every figure comes from the sealed ModelCap dataset published 15 September 2026; the page re-renders within a minute of each data refresh, and the ModelCap Index positions are the same ones shown on the live rankings.

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