What is the best alternative to Claude Opus 4.5?

GPT-5 Pro is the closest model that scores higher on the BenchLeader Index (59.8 against 59.7). For less money, Claude Opus 5.5 scores 69.2 at $8.00 per 1M tokens.

Is there a cheaper alternative to Claude Opus 4.5?

Yes: Claude Opus 5.5 (69.2, $8.00), Gemini 4 Carbon (68.9, $8.00) and GPT-6.1 Sol (67.2, $4.00), each within 4 Index points and cheaper than Claude Opus 4.5's $10.00.

Is there an open-source alternative to Claude Opus 4.5?

The best open-weights models on the BenchLeader Index are Kimi K3 (62.1), GLM-5 (60.2) and GLM 5.2 (60.1). You can download and run them yourself; check each licence on its model page.

How are these alternatives chosen?

From the models ranked on the BenchLeader Index today: the ones just above Claude Opus 4.5, cheaper ones within 4 points, ones at least 1.5× as fast within 4 points, and the best open-weights models. Prices are list prices blended three input tokens to one output.

Anthropic

Claude Opus 4.5 alternatives

Data as of 2 Nov 2026 · ranked on the BenchLeader Index

As of 2 Nov 2026, Claude Opus 4.5 by Anthropic scores 59.7 on the BenchLeader Index at $10.00 per 1M tokens blended. GPT-5 Pro scores higher (59.8); Claude Opus 5.5 is the best cheaper model within 4 points (69.2 at $8.00); Claude Opus 5.5 is at least 1.5× as fast at a similar score; Kimi K3 is the best open-weights option (62.1).

Scores higher

The closest models above Claude Opus 4.5 on the Index.

GPT-5 Pro OpenAI59.8 · $41.25
Grok 4.5 SpaceXAI59.8 · $3.00
GLM 5.2 Zhipu AI60.1 · $2.15

Cheaper, nearly as good

Within 4 Index points, for less per token.

Claude Opus 5.5 Anthropic compare69.2 · $8.00
Gemini 4 Carbon Google compare68.9 · $8.00
GPT-6.1 Sol OpenAI compare67.2 · $4.00
Gemini 4 Argon Google compare65.9 · $4.00
GPT-5.6 Sol OpenAI65.4 · $8.00

Faster

At least 1.5× the output speed, within 4 points.

Claude Opus 5.5 Anthropic compare69.2 · $8.00
Gemini 4 Carbon Google compare68.9 · $8.00
GPT-6.1 Sol OpenAI compare67.2 · $4.00

Open weights

The best models whose weights you can run yourself.

Kimi K3 Moonshot AI62.1 · $6.00
GLM-5 Zhipu AI60.2 · $1.55
GLM 5.2 Zhipu AI60.1 · $2.15

Every alternative side by side

Model	Index	$ / 1M blended	Tokens / s	Why
Claude Opus 4.5 (this model)	59.7	$10.00	57	–
Claude Opus 5.5	69.2	$8.00	96	cheaper, faster
Gemini 4 Carbon	68.9	$8.00	95	cheaper, faster
GPT-6.1 Sol	67.2	$4.00	87	cheaper, faster
Gemini 4 Argon	65.9	$4.00	83	cheaper
GPT-5.6 Sol	65.4	$8.00	127	cheaper
Kimi K3	62.1	$6.00	66	open weights
GLM-5	60.2	$1.55	62	open weights
GLM 5.2	60.1	$2.15	89	scores higher, open weights
GPT-5 Pro	59.8	$41.25	18	scores higher
Grok 4.5	59.8	$3.00	54	scores higher

Prices are list prices blended three input tokens to one output; speeds are measured medians, credited on each model page. The Index is BenchLeader's own, from independent benchmarks.

Questions people ask

What is the best alternative to Claude Opus 4.5?: GPT-5 Pro is the closest model that scores higher on the BenchLeader Index (59.8 against 59.7). For less money, Claude Opus 5.5 scores 69.2 at $8.00 per 1M tokens.
Is there a cheaper alternative to Claude Opus 4.5?: Yes: Claude Opus 5.5 (69.2, $8.00), Gemini 4 Carbon (68.9, $8.00) and GPT-6.1 Sol (67.2, $4.00), each within 4 Index points and cheaper than Claude Opus 4.5's $10.00.
Is there an open-source alternative to Claude Opus 4.5?: The best open-weights models on the BenchLeader Index are Kimi K3 (62.1), GLM-5 (60.2) and GLM 5.2 (60.1). You can download and run them yourself; check each licence on its model page.
How are these alternatives chosen?: From the models ranked on the BenchLeader Index today: the ones just above Claude Opus 4.5, cheaper ones within 4 points, ones at least 1.5× as fast within 4 points, and the best open-weights models. Prices are list prices blended three input tokens to one output.