Pairwise benchmark snapshot · Aug 17, 2026noindex (thin pair)

Claude Opus 4.8 vs OpenAI: gpt-oss-20b benchmark

Name: Claude Opus 4.8 vs OpenAI: gpt-oss-20b AI benchmark comparison
Creator: CompareLLM
License: https://creativecommons.org/licenses/by/4.0/

This page compares Claude Opus 4.8 (Anthropic) and OpenAI: gpt-oss-20b (OpenAI) using the latest snapshots we have as of Aug 17, 2026. OpenAI: gpt-oss-20b wins on output price at $0.13/1M. Claude Opus 4.8 has the larger context window (1M tokens). Every cell below is a dated snapshot from a named public source — we do not invent missing scores, and we do not run SWE-bench ourselves.

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Anthropic

Claude Opus 4.8

Prior Opus generation still billed at $5/$25. Kept as a compare baseline against Opus 5.

Elo 1,598$25/1M out

OpenAI

OpenAI: gpt-oss-20b

Auto-discovered from OpenRouter (openai/gpt-oss-20b). Preview until a second source matches.

$0.13/1M out

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Model A

Model B

Quick vs:vs Claude Opus 4.5 vs Claude Opus 4.6 vs Claude Sonnet 4.5 vs Claude 3.7 Sonnet

Interactive Comparison Diagram

Matchup Breakdown

Tug-of-War Matchup Matrix

Category wins across intelligence, speed, and pricing efficiency.

Claude Opus 4.8 (8)vsOpenAI: gpt-oss-20b (2)

Claude Opus 4.8: 8W (80%)Overall: Claude Opus 4.8OpenAI: gpt-oss-20b: 2W (20%)

← Claude Opus 4.8OpenAI: gpt-oss-20b →

Claude Opus 4.8 (5/5)

Intelligence & Reasoning

Preference Elo, Coding proficiency, SWE-bench & LiveBench accuracy

Preference Elo

1,598vs—

Coding Elo

1,604vs—

SWE-bench

78.4%vs—

LiveBench

73.6%vs—

GPQA Diamond

86.2%vs—

Claude Opus 4.8: 5WOpenAI: gpt-oss-20b: 0W

Claude Opus 4.8 (2/2)

Speed & Latency

Generation throughput and time to first token responsiveness

Output speed

66 tok/svs—

Time to first token

330 msvs—

Claude Opus 4.8: 2WOpenAI: gpt-oss-20b: 0W

OpenAI: gpt-oss-20b (2/3)

Pricing & Capacity

Cost per million tokens and max context window length

Output price

$25/1Mvs$0.13/1M

Input price

$5/1Mvs$0.03/1M

Context window

1Mvs131k

Claude Opus 4.8: 1WOpenAI: gpt-oss-20b: 2W

Capability Matchup Radar

Multi-Dimensional Capability Radar

Each spoke is a skill. Farther from the center is better (0–100th percentile). Tap any dot to inspect details.

Tap any node to inspect

Percentile 0–100

Dimensional AdvantageClaude Opus 4.8 5/6

Preference Elo

No shared data

Throughput Speed

No shared data

Price Efficiency

OpenAI: gpt-oss-20b

$24.87/1M cheaper

Full Benchmark Score Matrix

—

Elo

High is better

1,598

EloHigh is better

—

Code Elo

High is better

1,604

Code EloHigh is better

—

LiveBench

High is better

73.6%

LiveBenchHigh is better

—

SWE-bench

High is better

78.4%

SWE-benchHigh is better

—

GPQA

High is better

86.2%

GPQAHigh is better

—

TTFT

Low is better

330 ms

TTFTLow is better

—

Speed

High is better

66 tok/s

SpeedHigh is better

—

In $

Low is better

$5/1M

In $Low is better

$0.03/1M+16567%

Out $

Low is better

$25/1M

Out $Low is better

$0.13/1M+19131%

Context

High is better

+663%1M

ContextHigh is better

131k

Interactive Simulator

Workload Cost & Savings Calculator

Simulate monthly production API costs based on published $/1M tokens.

Save up to 99% with OpenAI: gpt-oss-20b

Monthly Volume50M tokens/mo

Quick Presets:

Token Ratio (In vs Out)70% In / 30% Out

RAG / Search (10% out)Coding / Chat (50% out)

Claude Opus 4.8$550.00 / mo

In: $175.00Out: $375.00

OpenAI: gpt-oss-20b$3.00 / mo

In: $1.05Out: $1.95

Estimated Cost Delta

OpenAI: gpt-oss-20b is estimated to save $547.00/month ($6,564/year).

Based on 50M tokens (30% gen)

Key Selection Recommendations

1
OpenAI: gpt-oss-20b:Pick OpenAI: gpt-oss-20b when you are optimizing output cost.
2
Claude Opus 4.8:Pick Claude Opus 4.8 for million-token RAG or long-document jobs.

Recommended Workload Routing

Repo / coding agentsinsufficient data

Need SWE-bench on both sides.

High-volume chatOpenAI: gpt-oss-20b

Lower output list price ($0.13/1M).

Voice / low-latency UIinsufficient data

Need TTFT on both sides.

Long-document RAGClaude Opus 4.8

Larger window (1M).

Screenshots / visionClaude Opus 4.8

Claude Opus 4.8 is the side marked multimodal in the catalog.

Target Workload	Recommended Pick	Evaluation Rationale
Repo / coding agents	insufficient data	Need SWE-bench on both sides.
High-volume chat	OpenAI: gpt-oss-20b	Lower output list price ($0.13/1M).
Voice / low-latency UI	insufficient data	Need TTFT on both sides.
Long-document RAG	Claude Opus 4.8	Larger window (1M).
Screenshots / vision	Claude Opus 4.8	Claude Opus 4.8 is the side marked multimodal in the catalog.

Related Editorial Dispatches & Benchmark Notes

View all news

launchJun 20, 2026

Keep Opus 4.8 on the board: a baseline, not a flagship

Opus 4.8 still bills $5/$25. We keep it so Opus 5 vs 4.8 is a real generation delta, not marketing.

Community Sentiment

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LIVE

Anthropic

Claude Opus 4.8

Elo 1,598

LiveBench73.6%

SWE-bench78.4%

Speed66 tok/s

Output cost$25/1M

OpenAI

OpenAI: gpt-oss-20b

Elo n/a

LiveBench—

SWE-bench—

Speed—

Output cost$0.13/1M

Frequently Asked Questions

Which is better overall, Claude Opus 4.8 or OpenAI: gpt-oss-20b?: We do not have preference Elo for both models, so we do not declare an overall winner. Compare the metrics that exist.
Which is better at coding, Claude Opus 4.8 or OpenAI: gpt-oss-20b?: SWE-bench is missing for at least one model, so we do not rank coding from a single number.
Which is cheaper to run in production?: OpenAI: gpt-oss-20b output tokens are $0.13/1M versus $25/1M. Input prices and retry rates still move the real bill.
Which is faster, Claude Opus 4.8 or OpenAI: gpt-oss-20b?: We do not have TTFT for both models.
Which has the larger context window?: Claude Opus 4.8 accepts 1M tokens versus 131k.
Can I self-host either model?: Neither model is marked open-weights here. You are comparing hosted APIs.
Are these scores from CompareLLM’s own evals?: No. V1 aggregates public leaderboards (and optional first-party latency pings). Each cell names its source and date. Read /methodology.
What does preference Elo mean on this page?: Preference Elo is a crowd vote from LMArena / Arena. People see two hidden answers and pick the one they like more. The model that wins more often gets a higher Elo. That means people preferred it — not that it passed a school test. It is not SWE-bench, not accuracy, and not a number we invent. Claude Opus 4.8 and OpenAI: gpt-oss-20b Elo cells are dated snapshots from the named source — we do not compute Arena ourselves.

Similar Head-to-Head Comparisons

All Claude Opus 4.8 matchups →|All OpenAI: gpt-oss-20b matchups →

Claude Opus 4.8 vs Claude Opus 4.6 (previous opus)Claude Opus 4.8 vs Claude Opus 5 (next opus)GPT-5.6 Sol vs Claude Opus 4.8 Claude Fable 5 vs Claude Opus 4.8 Claude Opus 4.5 vs Claude Opus 4.8 GPT-5 vs Claude Opus 4.8

Claude Opus 4.8 vs OpenAI: gpt-oss-20b benchmark

Interactive Comparison Diagram

Matchup Breakdown

Tug-of-War Matchup Matrix

Category wins across intelligence, speed, and pricing efficiency.

Claude Opus 4.8 (8)vsOpenAI: gpt-oss-20b (2)

Claude Opus 4.8: 8W (80%)Overall: Claude Opus 4.8OpenAI: gpt-oss-20b: 2W (20%)

← Claude Opus 4.8OpenAI: gpt-oss-20b →

Claude Opus 4.8 (5/5)

Intelligence & Reasoning

Preference Elo, Coding proficiency, SWE-bench & LiveBench accuracy

Preference Elo

1,598vs—

Coding Elo

1,604vs—

SWE-bench

78.4%vs—

LiveBench

73.6%vs—

GPQA Diamond

86.2%vs—

Claude Opus 4.8: 5WOpenAI: gpt-oss-20b: 0W

Claude Opus 4.8 (2/2)

Speed & Latency

Generation throughput and time to first token responsiveness

Output speed

66 tok/svs—

Time to first token

330 msvs—

Claude Opus 4.8: 2WOpenAI: gpt-oss-20b: 0W

OpenAI: gpt-oss-20b (2/3)

Pricing & Capacity

Cost per million tokens and max context window length

Output price

$25/1Mvs$0.13/1M

Input price

$5/1Mvs$0.03/1M

Context window

1Mvs131k

Claude Opus 4.8: 1WOpenAI: gpt-oss-20b: 2W

Recommended Workload Routing

Repo / coding agentsinsufficient data

Need SWE-bench on both sides.

High-volume chatOpenAI: gpt-oss-20b

Lower output list price ($0.13/1M).

Voice / low-latency UIinsufficient data

Need TTFT on both sides.

Long-document RAGClaude Opus 4.8

Larger window (1M).

Screenshots / visionClaude Opus 4.8

Claude Opus 4.8 is the side marked multimodal in the catalog.

Target Workload	Recommended Pick	Evaluation Rationale
Repo / coding agents	insufficient data	Need SWE-bench on both sides.
High-volume chat	OpenAI: gpt-oss-20b	Lower output list price ($0.13/1M).
Voice / low-latency UI	insufficient data	Need TTFT on both sides.
Long-document RAG	Claude Opus 4.8	Larger window (1M).
Screenshots / vision	Claude Opus 4.8	Claude Opus 4.8 is the side marked multimodal in the catalog.

Frequently Asked Questions

Which is better overall, Claude Opus 4.8 or OpenAI: gpt-oss-20b?

We do not have preference Elo for both models, so we do not declare an overall winner. Compare the metrics that exist.

Which is better at coding, Claude Opus 4.8 or OpenAI: gpt-oss-20b?

SWE-bench is missing for at least one model, so we do not rank coding from a single number.

Which is cheaper to run in production?

OpenAI: gpt-oss-20b output tokens are $0.13/1M versus $25/1M. Input prices and retry rates still move the real bill.

Which is faster, Claude Opus 4.8 or OpenAI: gpt-oss-20b?

We do not have TTFT for both models.

Which has the larger context window?

Claude Opus 4.8 accepts 1M tokens versus 131k.

Can I self-host either model?

Neither model is marked open-weights here. You are comparing hosted APIs.

Are these scores from CompareLLM’s own evals?

No. V1 aggregates public leaderboards (and optional first-party latency pings). Each cell names its source and date. Read /methodology.

What does preference Elo mean on this page?

Preference Elo is a crowd vote from LMArena / Arena. People see two hidden answers and pick the one they like more. The model that wins more often gets a higher Elo. That means people preferred it — not that it passed a school test. It is not SWE-bench, not accuracy, and not a number we invent. Claude Opus 4.8 and OpenAI: gpt-oss-20b Elo cells are dated snapshots from the named source — we do not compute Arena ourselves.

Swap or Add Any Model to this Matchup

Interactive Comparison Diagram

Tug-of-War Matchup Matrix

Intelligence & Reasoning

Speed & Latency

Pricing & Capacity

Multi-Dimensional Capability Radar

No shared data

No shared data

OpenAI: gpt-oss-20b

Full Benchmark Score Matrix

Workload Cost & Savings Calculator

Key Selection Recommendations

Recommended Workload Routing

Related Editorial Dispatches & Benchmark Notes

Keep Opus 4.8 on the board: a baseline, not a flagship

Cast Your Matchup Vote

Community Discussions (0)

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CompareLLM Matrix

Claude Opus 4.8

OpenAI: gpt-oss-20b

Frequently Asked Questions

Related news

Similar Head-to-Head Comparisons

Swap or Add Any Model to this Matchup

Interactive Comparison Diagram

Tug-of-War Matchup Matrix

Intelligence & Reasoning

Speed & Latency

Pricing & Capacity

Multi-Dimensional Capability Radar

No shared data

No shared data

OpenAI: gpt-oss-20b

Full Benchmark Score Matrix

Workload Cost & Savings Calculator

Key Selection Recommendations

Recommended Workload Routing

Related Editorial Dispatches & Benchmark Notes

Keep Opus 4.8 on the board: a baseline, not a flagship

Cast Your Matchup Vote

Community Discussions (0)

Share card

CompareLLM Matrix

Claude Opus 4.8

OpenAI: gpt-oss-20b

Frequently Asked Questions

Related news

Similar Head-to-Head Comparisons