Gemma 3 27B IT vs GPT OSS 20B

GPT OSS 20B leads llmrun Score 96.4 to 79.4; both fit 24 GB at Q4_K_M; GPT OSS 20B is 5.3× faster on RTX 4090 (~190 vs ~36 tok/s).

Model A · Google

Gemma 3 27B IT

79.4llmrun Score

27.4B · 128K context · Gemma Terms · Mar 2025

Vision

Model B · OpenAI

GPT OSS 20B

96.4llmrun Score

20.9B · 4.2B active · 128K context · Apache 2.0 · Aug 2025

ChatFunctions

Which should you choose?

Choose Gemma 3 27B IT if you want…

Also does vision
GPT OSS 20B doesn't list it

Choose GPT OSS 20B if you want…

Higher llmrun Score
96.4 vs 79.4
Stronger at coding
101.9 vs 69.9
Stronger at reasoning
91.3 vs 73.8
Ahead on the benchmarks
7 of 7 shared boards
Fits a 12 GB GPU
IQ4_XS · 11.8 GB; Gemma 3 27B IT needs 11.9 GB at its smallest quant
5.3× faster on RTX 4090
~190 vs ~36 tok/s

On your hardware

Each model at its default quant (Q4_K_M), a smaller one when it must. Estimates, ±20%.

MemoryGemma 3 27B ITGPT OSS 20B

8 GB

RTX 4060 · 8 GB tier

Gemma 3 27B IT

Doesn't fit

smallest quant needs 11.9 GB

GPT OSS 20B

IQ2_M · ~103 tok/s

7.6 GB · up to 32Kfits

12 GB

RTX 3060 12GB · 12 GB tier

Gemma 3 27B IT

IQ2_XXS · ~28 tok/s

11.9 GB · up to 16K

GPT OSS 20B

IQ4_XS · ~89 tok/s

11.8 GB · up to 16Kbetter quant

16 GB

RTX 5060 Ti 16GB · 16 GB tier

Gemma 3 27B IT

Q2_K_S · ~24 tok/s

15.7 GB · up to 16K

GPT OSS 20B

Q4_K_M · ~98 tok/s

13.1 GB · up to 128Kmore headroom

24 GBreference

RTX 4090 · 24 GB tier

Gemma 3 27B IT

Q4_K_M · ~36 tok/s

21.7 GB · up to 16K

GPT OSS 20B

Q4_K_M · ~190 tok/s

13.1 GB · up to 128Kfaster

32 GB

RTX 5090 · 32 GB tier

Gemma 3 27B IT

Q4_K_M · ~64 tok/s

21.7 GB · up to 32K

GPT OSS 20B

Q4_K_M · ~282 tok/s

13.1 GB · up to 128Kfaster

48 GB

RTX A6000 · 48 GB tier

Gemma 3 27B IT

Q4_K_M · ~28 tok/s

21.7 GB · up to 64K

GPT OSS 20B

Q4_K_M · ~154 tok/s

13.1 GB · up to 128Kfaster

Mac 32 GB

Mac Mini M4 · Macs

Gemma 3 27B IT

Q4_K_M · ~5 tok/s

21.7 GB · up to 32K

GPT OSS 20B

Q4_K_M · ~28 tok/s

13.1 GB · up to 128Kfaster

Mac 64 GB

Mac Studio M4 Max · Macs

Gemma 3 27B IT

Q4_K_M · ~21 tok/s

21.7 GB · up to 128K

GPT OSS 20B

Q4_K_M · ~86 tok/s

13.1 GB · up to 128Kfaster

Mac 128 GB

Mac Studio M4 Max · Macs

Gemma 3 27B IT

Q4_K_M · ~21 tok/s

21.7 GB · up to 128K

GPT OSS 20B

Q4_K_M · ~86 tok/s

13.1 GB · up to 128Kfaster

Reference GPU: RTX 4090. Tinted cell = the better pick on that machine (fits, more headroom, or at least 10% faster).

llmrun Score

with its 90% range · bars share one scale

Gemma 3 27B IT GPT OSS 20B

Overall

Gemma 3 27B IT

79.475–83

GPT OSS 20B

96.493–100

Coding

Gemma 3 27B IT

69.954–86

GPT OSS 20B

101.993–111

Science

Gemma 3 27B IT

80.872–90

GPT OSS 20B

93.186–101

Reasoning

Gemma 3 27B IT

73.862–86

GPT OSS 20B

91.383–100

Gemma 3 27B IT · #91 of 106 open models · #26 of 36 that fit 24 GB

GPT OSS 20B · #69 of 106 open models · #16 of 36 that fit 24 GB

Benchmarks

7 shared boards: Gemma 3 27B IT leads 0, GPT OSS 20B leads 7 · Benchmarks imported Nov 2026

BoardGemma 3 27B ITGPT OSS 20B

GPQA Diamond

Gemma 3 27B IT

47.7%#59/100 open

IndependentEpoch AI · Mar 2025

GPT OSS 20B

60.8%#44/100 open

IndependentEpoch AI · Aug 2025

AIME 2024/2025

Gemma 3 27B IT

22.5%#54/88 open

IndependentEpoch AI · Mar 2025

GPT OSS 20B

65.3%#36/88 open

IndependentEpoch AI · Aug 2025

MMLU-Pro

Gemma 3 27B IT

67.5%#43/146 open

IndependentTIGER-Lab

GPT OSS 20B

73.6%#33/146 open

IndependentTIGER-Lab

SciCode

Gemma 3 27B IT

23.3%#67/72 open

Lab-reportedEpoch AI · Mar 2025

GPT OSS 20B

38.9%#41/72 open

Lab-reportedEpoch AI · Aug 2025

CritPt

Gemma 3 27B IT

0.0%#58/84 open

Lab-reportedEpoch AI · Mar 2025

GPT OSS 20B

1.4%#36/84 open

Lab-reportedEpoch AI · Aug 2025

DTBench

Gemma 3 27B IT

52.5%#59/70 open

Lab-reportedEpoch AI · Mar 2025

GPT OSS 20B

68.0%#36/70 open

Lab-reportedEpoch AI · Aug 2025

LMCA

Gemma 3 27B IT

12.3%#47/56 open

Lab-reportedEpoch AI · Mar 2025

GPT OSS 20B

14.5%#45/56 open

Lab-reportedEpoch AI · Aug 2025

7 more boards (other shared and single-model boards)

LMArena Text

Gemma 3 27B IT

1365.3#67/188 open

ArenaLMArena · Oct 2026

GPT OSS 20B

1317.3#98/188 open

ArenaLMArena · Oct 2026

Only Gemma 3 27B IT (3)

Only GPT OSS 20B (3)

VRAM by quantization

Memory to load the model and 2K context; below it, the total at 32K and 128K context. Lighter side in bold.

QuantGemma 3 27B ITGPT OSS 20B

Q2_K

Gemma 3 27B IT

12.8 GB10.5 GB file

32K 20.6 GB · 128K 45.4 GB

GPT OSS 20B

9.3 GB11.5 GB file

32K 9.8 GB · 128K 11.5 GB

Q3_K_S

Gemma 3 27B IT

13.2 GB12.2 GB file

32K 21.0 GB · 128K 45.8 GB

GPT OSS 20B

9.5 GB11.5 GB file

32K 10.0 GB · 128K 11.7 GB

Q3_K_M

Gemma 3 27B IT

14.7 GB13.4 GB file

32K 22.5 GB · 128K 47.3 GB

GPT OSS 20B

10.6 GB11.5 GB file

32K 11.1 GB · 128K 12.8 GB

Q4_0

Gemma 3 27B IT

15.1 GB15.6 GB file

32K 22.9 GB · 128K 47.7 GB

GPT OSS 20B

10.8 GB11.5 GB file

32K 11.3 GB · 128K 13.0 GB

Q4_K_M

Gemma 3 27B IT

18.1 GB16.5 GB file

32K 25.9 GB · 128K 50.7 GB

GPT OSS 20B

12.9 GB11.6 GB file

32K 13.4 GB · 128K 15.1 GB

Q5_K_M

Gemma 3 27B IT

21.5 GB19.3 GB file

32K 29.3 GB · 128K 54.1 GB

GPT OSS 20B

15.3 GB11.7 GB file

32K 15.8 GB · 128K 17.5 GB

Q6_K

Gemma 3 27B IT

24.9 GB22.2 GB file

32K 32.7 GB · 128K 57.5 GB

GPT OSS 20B

17.6 GB12.0 GB file

32K 18.1 GB · 128K 19.8 GB

Q8_0

Gemma 3 27B IT

30.2 GB28.7 GB file

32K 37.9 GB · 128K 62.8 GB

GPT OSS 20B

21.3 GB~20.9 GB file

32K 21.8 GB · 128K 23.5 GB

20 more quants

IQ2_XXS

Gemma 3 27B IT

8.3 GB7.9 GB file

32K 16.1 GB · 128K 40.9 GB

GPT OSS 20B

6.1 GB~5.8 GB file

32K 6.6 GB · 128K 8.3 GB

IQ2_XS

Gemma 3 27B IT

9.1 GB8.4 GB file

32K 16.8 GB · 128K 41.7 GB

GPT OSS 20B

6.7 GB~6.3 GB file

32K 7.2 GB · 128K 8.9 GB

IQ2_S

Gemma 3 27B IT

9.4 GB8.8 GB file

32K 17.2 GB · 128K 42.0 GB

GPT OSS 20B

6.9 GB~6.5 GB file

32K 7.4 GB · 128K 9.1 GB

IQ2_M

Gemma 3 27B IT

10.2 GB9.6 GB file

32K 17.9 GB · 128K 42.8 GB

GPT OSS 20B

7.4 GB~7.1 GB file

32K 7.9 GB · 128K 9.6 GB

IQ3_XXS

Gemma 3 27B IT

11.7 GB10.8 GB file

32K 19.5 GB · 128K 44.3 GB

GPT OSS 20B

8.5 GB11.6 GB file

32K 9.0 GB · 128K 10.7 GB

Q2_K_S

Gemma 3 27B IT

12.1 GB9.8 GB file

32K 19.8 GB · 128K 44.7 GB

GPT OSS 20B

8.7 GB12.1 GB file

32K 9.2 GB · 128K 10.9 GB

IQ3_XS

Gemma 3 27B IT

12.5 GB11.6 GB file

32K 20.2 GB · 128K 45.1 GB

GPT OSS 20B

9.0 GB11.6 GB file

32K 9.5 GB · 128K 11.2 GB

IQ3_S

Gemma 3 27B IT

12.8 GB12.2 GB file

32K 20.6 GB · 128K 45.4 GB

GPT OSS 20B

9.3 GB12.1 GB file

32K 9.8 GB · 128K 11.5 GB

IQ3_M

Gemma 3 27B IT

13.6 GB12.5 GB file

32K 21.3 GB · 128K 46.2 GB

GPT OSS 20B

9.8 GB11.6 GB file

32K 10.3 GB · 128K 12.0 GB

Q3_K_L

Gemma 3 27B IT

15.5 GB14.5 GB file

32K 23.2 GB · 128K 48.1 GB

GPT OSS 20B

11.1 GB11.5 GB file

32K 11.6 GB · 128K 13.3 GB

IQ4_XS

Gemma 3 27B IT

16.2 GB14.8 GB file

32K 24.0 GB · 128K 48.8 GB

GPT OSS 20B

11.6 GB11.6 GB file

32K 12.1 GB · 128K 13.8 GB

IQ4_NL

Gemma 3 27B IT

17.0 GB15.6 GB file

32K 24.7 GB · 128K 49.6 GB

GPT OSS 20B

12.1 GB11.6 GB file

32K 12.6 GB · 128K 14.3 GB

Q4_1

Gemma 3 27B IT

17.0 GB17.2 GB file

32K 24.7 GB · 128K 49.6 GB

GPT OSS 20B

12.1 GB11.6 GB file

32K 12.6 GB · 128K 14.3 GB

Q4_K_S

Gemma 3 27B IT

17.0 GB15.7 GB file

32K 24.7 GB · 128K 49.6 GB

GPT OSS 20B

12.1 GB11.6 GB file

32K 12.6 GB · 128K 14.3 GB

Q4_K_L

Gemma 3 27B IT

18.5 GB16.9 GB file

32K 26.2 GB · 128K 51.1 GB

GPT OSS 20B

13.2 GB11.9 GB file

32K 13.7 GB · 128K 15.4 GB

Q5_0

Gemma 3 27B IT

18.9 GB18.8 GB file

32K 26.6 GB · 128K 51.5 GB

GPT OSS 20B

not listed

Q5_1

Gemma 3 27B IT

20.8 GB20.4 GB file

32K 28.5 GB · 128K 53.4 GB

GPT OSS 20B

not listed

Q5_K_S

Gemma 3 27B IT

20.8 GB18.8 GB file

32K 28.5 GB · 128K 53.4 GB

GPT OSS 20B

14.8 GB11.7 GB file

32K 15.3 GB · 128K 17.0 GB

Q5_K_L

Gemma 3 27B IT

21.9 GB19.6 GB file

32K 29.6 GB · 128K 54.5 GB

GPT OSS 20B

15.5 GB11.9 GB file

32K 16.0 GB · 128K 17.7 GB

BF16

Gemma 3 27B IT

60.4 GB54.0 GB file

32K 68.1 GB · 128K 93.0 GB

GPT OSS 20B

42.2 GB~41.8 GB file

32K 42.7 GB · 128K 44.4 GB

How to run each

Gemma 3 27B IT

Ollama · Q4_K_M

$ollama run hf.co/unsloth/gemma-3-27b-it-GGUF:Q4_K_M

All ways to run Gemma 3 27B IT →

GPT OSS 20B

Ollama · Q4_K_M

$ollama run hf.co/unsloth/gpt-oss-20b-GGUF:Q4_K_M

All ways to run GPT OSS 20B →

Specifications

Specifications of Gemma 3 27B IT and GPT OSS 20B
Spec	Gemma 3 27B IT	GPT OSS 20B
Publisher	Google	OpenAI
Parameters	27.4B	20.9B
Active parameters	—	4.2B per token
Architecture	—	GptOssForCausalLM
Context	128K tokens	128K tokens
Modalities	Vision	Chat, Function-calling
License	Gemma Terms	Apache 2.0
Released	Mar 2025	Aug 2025

Frequently Asked Questions

Which is better, Gemma 3 27B IT or GPT OSS 20B?

GPT OSS 20B leads llmrun Score 96.4 to 79.4; both fit 24 GB at Q4_K_M; GPT OSS 20B is 5.3× faster on RTX 4090 (~190 vs ~36 tok/s). Choose Gemma 3 27B IT for also does vision; choose GPT OSS 20B for higher llmrun Score and stronger at coding.

Which needs less VRAM, Gemma 3 27B IT or GPT OSS 20B?

At Q4_K_M, Gemma 3 27B IT requires 18.1 GB while GPT OSS 20B needs 12.9 GB, making GPT OSS 20B the easier model to run on your local setup.

Which is faster on RTX 4090?

Estimated decode speed on RTX 4090 is about 36 tok/s for Gemma 3 27B IT (Q4_K_M) and 190 tok/s for GPT OSS 20B (Q4_K_M), so GPT OSS 20B is faster. Estimates, ±20%.

Can I run Gemma 3 27B IT or GPT OSS 20B on a 16 GB GPU?

Gemma 3 27B IT fits at Q2_K_S; GPT OSS 20B fits at Q4_K_M.

Which has a longer context window, Gemma 3 27B IT or GPT OSS 20B?

Gemma 3 27B IT supports 131,072 tokens and GPT OSS 20B supports 131,072 tokens.