Claude 4.5 Sonnet and Opus: Everything We Know About Anthropic's New Models

The Evolution of Claude Models: From 1.0 to 4.5

Anthropic has been surprising the market with each new generation of Claude. From Claude 1.0, launched in 2023, to the current Claude 4.5, the evolution has been dramatic:30x fasterin coding,10x larger context window(from 9k to 1M tokens), and capabilities that no model had 2 years ago -- likecomputer use, extended thinking e tool use native.

Claude 4.5 represents the highest point on this route. With two main models --Sonnet 4.5(fast and cheap) andOpus 4.5(maximum performance) -- Anthropic serves both those who need speed and those who need depth.

model	Context	Speed	Input Price/1M	Output Price/1M	Best for
Claude 3.5 Sonnet	200K	Fast	$3	$15	General use
Claude 4 Opus	200K	Medium	$15	$75	Complex reasoning
Claude 4.5 Sonnet	1M	Very fast	$3	$15	Coding + speed
Claude 4.5 Opus	1M	Fast	$15	$75	Critical tasks

Claude 4.5 Sonnet: The Best Value for Money in Coding

The Sonnet 4.5 is, without exaggeration, the best cost-benefit model forsoftware developmentin 2026. In Anthropic's internal benchmarks, it outperforms GPT-4o by:

• SWE-bench:72.3% vs 64.1% (GPT-4o) -- solving real bugs in open-source repositories
• HumanEval:94.7% vs 90.2% -- generating correct functions from docstrings
• MMLU:90.1% vs 88.7% -- general academic knowledge
• Extended thinking:Ability to "think" for up to 128K tokens before responding, improving complex responses by 40%

No Claude Code, Sonnet 4.5 is the standard model. He writes, debugs, refactors and tests code with a fluency that feels like having a senior pair programmer at your side. And with context windowwindow from the beginning. 1 million tokens, it can read entire repositories without losing context.

Claude 4.5 Opus: For When You Need the Best

The Opus 4.5 is Anthropic's most powerful model -- and one of the most powerful in the world. It excels at tasks that require:

• Multi-step reasoning:Solve problems that require 10+ logical chained steps
• Analysis of long documents:Read contracts, academic papers, and entire codebases accurately
• Structured creativity:Write long texts maintaining coherence and quality from start to finish
• Critical coding:Complex refactorings, framework migration, systems architecture

The price is 5x higher than Sonnet, but for critical tasks -- such as security audits, legal analysis or software architecture -- the difference in quality justifies the investment. NodeClaude Code, you can switch between Sonnet and Opus using/modeldepending on the complexity of the task.

Extended Thinking: The Resource That Changes Everything

Extended thinkingIt is perhaps the most important innovation in Claude 4.5. Instead of responding immediately, the model internally “thinks” for up to 128,000 tokens before giving the final response. This results in:

• +40% de accuracyin mathematics and logic problems
• +35% betterin complex coding tasks (refactoring, debugging)
• More complete answersthat consider edge cases and alternatives

In Claude Code, extended thinking is automatically enabled for complex tasks. You can see it "thinking" in real time before generating the code. This is especially powerful withCLAUDE.mdwell configured -- the model uses thinking time to align the answer with the design rules.

Practical tip:If a task is simple (rename variable, add import), use Sonnet without extended thinking. If it is complex (architect new feature, migrate framework), activate Opus with extended thinking. The right combination saves70% of costswithout sacrificing quality.

How to Migrate to Claude 4.5 in Claude Code

If you already use Claude Code, migrating to the new models is simple:

1. Update Claude Code: claude update(version 2.1+ already includes Claude 4.5)
2. Select the model: Use /modelin the terminal to switch between Sonnet and Opus
3. Set up in CLAUDE.md:Addprefer-model: claude-sonnet-4-5to define the project standard
4. Use optimized skills:SkillsMega Bundleare already compatible with Claude 4.5

Important:The 1M token context window changes how you work. Previously, you had to be surgical about which files to include in context. Now, you can give the entire repository and the model understands the relationships between the files. This is transformative for refactoring and debugging.

FAQ

What is the difference between Claude 4.5 Sonnet and Opus?

Sonnet is faster and cheaper (ideal for everyday coding). Opus is more powerful (ideal for complex tasks such as architecture, legal analysis or critical debugging). Both have 1M context tokens.

Claude 4.5 is better than GPT-4o?

In coding yes -- Claude 4.5 Sonnet outperforms GPT-4o in SWE-bench (72.3% vs 64.1%) and HumanEval (94.7% vs 90.2%). In general tasks, the models are comtoble, with each having strengths in specific areas.

Do I need to pay more to use Claude 4.5?

At Claude Code, you already have access to Sonnet 4.5 with the standard subscription. Opus 4.5 requires Pro plan or use via API. API prices are the same as previous models in the same tier.

Read also

AI Timeline: From 2020 to 2026

Ano	Marco	Impacto
2020	GPT-3 lancado	Primeira IA de linguagem "impressionante" to o publico
2021	DALL-E, Codex	IA comeca a gerar imagens e codigo
2022	ChatGPT, Stable Diffusion	Explosao mainstream. 100M usuarios em 2 meses
2023	GPT-4, Claude 2, Midjourney v5	IA atinge nivel professional em texto e imagem
2024	Claude 3.5, Gemini 1.5, Sora	Context windows de 1M+, video gerado por IA
2025	Claude Code, Cursor AI, AI Agents	IA vai do chat to a execucao autonoma
2026	Claude 4.6, GPT-5, Gemini 2.5	Agents autonomos, IA em 72% das empresas, regulamentacao global

A velocidade de evolucao e exponencial. O que levou 2 anos (2020-2022) agora acontece em 2 meses. Profissionais que se atualizam continuamente tem vantagem competitiva massiva sobre quem "espera a poeira baixar".

Generative AI vs Predictive AI vs Autonomous AI: Understanding the Differences

Tipo	O que faz	Exemplo	Aplicacao
IA Generativa	Cria conteudo novo (texto, imagem, codigo, video)	Claude, ChatGPT, Midjourney	Criacao de conteudo, coding, design
IA Preditiva	Analisa dados e preve resultados futuros	Modelos de ML, forecasting	Previsao de vendas, churn, demanda
IA Autonoma (Agentic)	Toma decisoes e executa acoes sem intervencao humana	AI Agents, Claude Code agents	Automacao end-to-end, operacoes
IA Conversacional	Dialoga naturalmente com humans	Chatbots, assistentes virtuais	Atendimento, suporte, vendas
IA Multimodal	Processa multiplos tipos de input (texto+imagem+audio)	GPT-4o, Gemini 2.5, Claude 4.6	Analise de documentos, acessibilidade

Em 2026, a fronteira mais quente e a IA Autonoma (Agentic AI). A transicao de "IA que responde" to "IA que faz" esta redefinindo o que e possivel automatizar. Gartner preve que 15% das decisoes empresariais serao tomadas por AI Agents ate 2028.

Advanced Prompt Engineering: 7 Techniques Professionals Use

1. Chain-of-Thought (CoT): Peca a IA to "pensar passo a passo". Melhora accuracy em problemas logicos em 40-60%. Exemplo: "Analise este problema passo a passo antes de dar a resposta final."
2. Few-Shot com exemplos: Forneca 2-3 exemplos do output desejado. A IA detecta o padrao e replica. Essencial to formatacao consistente.
3. Role prompting: "Voce e um senior developer com 15 anos de experiencia em React." Define o nivel de expertise da resposta.
4. Constraint prompting: Defina limites claros: "Responda em no maximo 3 tografos, use bullet points, inclua 1 tabela."
5. Meta-prompting: Peca a IA to melhorar seu proprio prompt: "Como voce reescreveria este prompt to obter uma resposta melhor?"
6. Reverse prompting: De um output bom e peca a IA to gerar o prompt que o produziria. Otimo to criar templates reutilizaveis.
7. Tree-of-Thought: Peca a IA to explorar 3 abordagens diferentes antes de escolher a melhor. Reduz vieses e encontra solucoes criativas.

Com skills do Mega Bundle minhaskills.io, essas tecnicas ja vem embutidas nos templates — voce nao precisa lembrar de cada uma.