Llama 3.1 8B Instruct vs Phi 4
Updated October 21, 2026. 44 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.
Decision reading
Neither model has a coding score yet, so the two cannot be ranked on coding.
Llama 3.1 8B Instruct has the edge where output tokens cost 1.8x less, and where the context window is larger, 131K against 16K tokens.
- Shared results
- 44
- Llama 3.1 8B Instruct only
- 6
- Phi 4 only
- 1
- Like-for-like categories
- 7 of 9
Shared results can support a head-to-head reading. Results only one model has describe coverage, not superiority.
Which one for your work
Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.
Coding
Vibe Coding Index, six public coding benchmarks
No call
Neither has a coding score yet.
One side not measured
Intelligence
AA Intelligence Index
Llama 3.1 8B Instruct
Llama 3.1 8B Instruct leads, 6.9 against 5.9.
Same board, both measured
Long documents
Listed context window
Llama 3.1 8B Instruct
Llama 3.1 8B Instruct takes 131K tokens against 16K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Llama 3.1 8B Instruct
Llama 3.1 8B Instruct $0.0001, Phi 4 $0.0001 per turn.
List prices
At a glance
- Coding index
- Llama 3.1 8B Instruct not benchmarked, Phi 4 not benchmarked.
- Widest category
- Math, 17.5 points apart on average over 6 shared benchmarks.
- Widest single gap
- MATH level 5: Llama 3.1 8B Instruct 22.9% against Phi 4 64.9%, 42.1 points apart on a 0 to 100 scale.
- Output price
- Llama 3.1 8B Instruct $0.08 against Phi 4 $0.14 per million output tokens, 1.8x apart.
- Context window
- Llama 3.1 8B Instruct takes 131K tokens, Phi 4 16K.
Benchmark by benchmark
First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.
| Category | Llama 3.1 8B Instruct | Bars | Phi 4 | Ties |
|---|---|---|---|---|
| Coding | 0 | 4 | ||
| Intelligence | 1 | 1 | ||
| Agentic work | 2 | 0 | ||
| Reasoning | 1 | 5 | ||
| Math | 0 | 6 | ||
| Knowledge | 0 | 6 | ||
| General | 2 | 16 | ||
| All shared boards | 6 | 38 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index04
| Benchmark | Llama 3.1 8B Instruct | Phi 4 | Leader |
|---|---|---|---|
| AA Coding Index | 5.4 | Not measured | Only Llama 3.1 8B Instruct measured |
| LiveCodeBench (Artificial Analysis run) | 11.6% | 23.1% | Phi 4 |
| Terminal-Bench Hard (Artificial Analysis run) | 0.8% | 3.8% | Phi 4 |
| WeirdML | 1.7% | Not measured | Only Llama 3.1 8B Instruct measured |
| LMArena Text: coding | 1195 | 1231 | Phi 4 |
| LMArena Text: software and IT | 1195 | 1228 | Phi 4 |
| Neither model has a result on the other 32 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index11
| Benchmark | Llama 3.1 8B Instruct | Phi 4 | Leader |
|---|---|---|---|
| AA Intelligence Index | 6.9 | 5.9 | Llama 3.1 8B Instruct |
| Epoch Capabilities Index | 116.5 | 130.5 | Phi 4 |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Llama 3.1 8B Instruct | Phi 4 | Leader |
|---|---|---|---|
| τ²-Bench Telecom | 16.4% | 0.0% | Llama 3.1 8B Instruct |
| BALROG | 15.1% | 11.6% | Llama 3.1 8B Instruct |
| Neither model has a result on the other 37 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index15
| Benchmark | Llama 3.1 8B Instruct | Phi 4 | Leader |
|---|---|---|---|
| GPQA Diamond (Artificial Analysis run) | 25.9% | 57.5% | Phi 4 |
| Humanity's Last Exam (Artificial Analysis run) | 5.3% | 3.8% | Llama 3.1 8B Instruct |
| GPQA Diamond (Epoch AI run) | 27.0% | 56.1% | Phi 4 |
| LMArena Text: hard prompts | 1175 | 1220 | Phi 4 |
| LMArena Text: expert | 1144 | 1203 | Phi 4 |
| LMArena Text: hard prompts in English | 1196 | 1230 | Phi 4 |
| Neither model has a result on the other 15 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index06
| Benchmark | Llama 3.1 8B Instruct | Phi 4 | Leader |
|---|---|---|---|
| AA Math Index | 4.3 | 18.0 | Phi 4 |
| AIME 2025 (Artificial Analysis run) | 4.3% | 18.0% | Phi 4 |
| OTIS Mock AIME | 1.7% | 13.8% | Phi 4 |
| MATH level 5 | 22.9% | 64.9% | Phi 4 |
| GSM8K | 82.4% | Not measured | Only Llama 3.1 8B Instruct measured |
| LMArena Text: math | 1179 | 1246 | Phi 4 |
| LMArena Text: mathematical work | 1180 | 1254 | Phi 4 |
| Neither model has a result on the other 6 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index06
| Benchmark | Llama 3.1 8B Instruct | Phi 4 | Leader |
|---|---|---|---|
| MMLU Pro (Artificial Analysis run) | 47.6% | 71.4% | Phi 4 |
| MMLU | 56.1% | 84.8% | Phi 4 |
| LMArena Text: science | 1193 | 1206 | Phi 4 |
| LMArena Text: medicine and healthcare | 1182 | 1202 | Phi 4 |
| LMArena Text: legal and government | 1206 | 1241 | Phi 4 |
| LMArena Text: business and finance | 1166 | 1199 | Phi 4 |
| Neither model has a result on the other 11 boards here | |||
Web designNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Llama 3.1 8B Instruct | Phi 4 | Leader |
|---|---|---|---|
| Neither model has a result on 9 boards here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index216
| Benchmark | Llama 3.1 8B Instruct | Phi 4 | Leader |
|---|---|---|---|
| IFBench | 28.6% | 23.5% | Llama 3.1 8B Instruct |
| Long context reasoning (AA-LCR) | 18.0% | 0.0% | Llama 3.1 8B Instruct |
| DTBench | 50.9% | Not measured | Only Llama 3.1 8B Instruct measured |
| LMCA | 5.4% | Not measured | Only Llama 3.1 8B Instruct measured |
| Creative writing (Lech Mazur) | Not measured | 62.6% | Only Phi 4 measured |
| PIQA | 81.2% | Not measured | Only Llama 3.1 8B Instruct measured |
| LMArena Text | 1187 | 1217 | Phi 4 |
| LMArena Text: instruction following | 1159 | 1201 | Phi 4 |
| LMArena Text: creative writing | 1154 | 1181 | Phi 4 |
| LMArena Text: English | 1218 | 1231 | Phi 4 |
| LMArena Text: non-English | 1148 | 1197 | Phi 4 |
| LMArena Text: Chinese | 1151 | 1212 | Phi 4 |
| LMArena Text: German | 1144 | 1222 | Phi 4 |
| LMArena Text: Japanese | 1061 | 1158 | Phi 4 |
| LMArena Text: Korean | 1053 | 1151 | Phi 4 |
| LMArena Text: French | 1178 | 1224 | Phi 4 |
| LMArena Text: Spanish | 1169 | 1234 | Phi 4 |
| LMArena Text: Russian | 1158 | 1209 | Phi 4 |
| LMArena Text: multi-turn | 1172 | 1206 | Phi 4 |
| LMArena Text: longer queries | 1181 | 1217 | Phi 4 |
| LMArena Text: writing and language | 1162 | 1198 | Phi 4 |
| LMArena Text: entertainment and media | 1145 | 1162 | Phi 4 |
| Neither model has a result on the other 24 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Llama 3.1 8B Instruct | Phi 4 | Leader |
|---|---|---|---|
| Neither model has a result on 5 boards here | |||
What each workload costs
Three fixed token mixes at each model's listed price, so per-token rates become a bill.
Chat turn
1K input + 500 output tokens
Llama 3.1 8B Instruct costs less
Repository review
50K input + 3K output tokens
Llama 3.1 8B Instruct costs less
Agent loop
200K input + 10K output tokens
Llama 3.1 8B Instruct costs less
Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.
Specification differences
The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.
| Specification | Meta Llama 3.1 8B Instruct | Microsoft Phi 4 |
|---|---|---|
| Maker | Meta Llama | Microsoft |
| Weights | Open weights | Open weights |
| Released | July 23, 2024 | January 10, 2025 |
| Context window | 131K | 16K |
| Input $/Mtok | $0.05 | $0.07 |
| Output $/Mtok | $0.08 | $0.14 |
| Coding index | Not benchmarked | Not benchmarked |
| Independent measurements behind it | 0 | 0 |
| Cost per solved task | Not computable | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Llama 3.1 8B Instruct better than Phi 4 for coding?
Neither model has a coding score yet, so the two cannot be ranked on coding. Llama 3.1 8B Instruct has the edge where output tokens cost 1.8x less, and where the context window is larger, 131K against 16K tokens.
Which is cheaper, Llama 3.1 8B Instruct or Phi 4?
Llama 3.1 8B Instruct costs $0.05 per million input tokens and $0.08 per million output tokens; Phi 4 costs $0.07 and $0.14. Cost per solved task is known for neither of them.
Which has the bigger context window, Llama 3.1 8B Instruct or Phi 4?
Llama 3.1 8B Instruct, with 131K tokens against 16K.
How many benchmarks is the Llama 3.1 8B Instruct vs Phi 4 comparison based on?
44 benchmarks have a result for both models as of October 21, 2026. Llama 3.1 8B Instruct's coding index rests on 0 independent benchmarks and Phi 4's on 0. Where only one model has a result, the page says so instead of naming a winner.