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Claude Sonnet 4.6 vs GPT-5.5: Same Context, Half the Price

For the first time, two flagship-class models from Anthropic and OpenAI offer the same 1M token context window — but at radically different prices. Claude Sonnet 4.6 costs $3/$15 per million tokens. GPT-5.5 costs $5/$30. That's a 40-50% price gap for the same context capacity.

This comparison breaks down exactly what you get at each price point, when the premium is worth paying, and where Sonnet 4.6 is the clear winner.

Head-to-Head: Pricing Comparison

Feature	Claude Sonnet 4.6 (Anthropic)	GPT-5.5 (OpenAI)
Input ($/1M tokens)	$3.00	$5.00
Output ($/1M tokens)	$15.00	$30.00
Context Window	1M tokens	1M tokens
Max Output	64K tokens	64K tokens
Tier	Mid	Premium
Batch API	50% off ($1.50/$7.50)	50% off ($2.50/$15.00)
Input cost vs competitor	40% cheaper	67% more expensive
Output cost vs competitor	50% cheaper	100% more expensive

Claude Sonnet 4.6 is 40% cheaper on input and 50% cheaper on output — with the same 1M context window. This is unusual. Typically, cheaper models sacrifice context length. Here, you get identical context at half the price.

Monthly Cost Scenarios

Small App: 1K requests/day, 2K tokens avg (500 in / 1.5K out)

Medium App: 10K requests/day, 3K tokens avg (1K in / 2K out)

Scale App: 50K requests/day, 2K tokens avg (500 in / 1.5K out)

Batch Processing: 100K requests/day, 1K tokens avg (non-urgent)

At every scale, Sonnet 4.6 saves 60-70% compared to GPT-5.5. At the scale tier, that's $94,500/year. Even with Batch API discounts on both sides, the gap remains massive.

When GPT-5.5 Wins: Premium Quality

GPT-5.5 is OpenAI's most capable non-reasoning model. The premium price buys:

• Superior instruction following: GPT-5.5 is more precise at following complex, multi-step instructions without drift
• Better multi-modal reasoning: Stronger at tasks combining text, images, and structured data
• More consistent output quality: Less variance across runs, important for production reliability
• GPT-5.5 Pro option: If you need even more capability, GPT-5.5 Pro ($30/$180) is available — Sonnet has no equivalent tier
• Ecosystem integration: Native integration with ChatGPT, Assistants API, and OpenAI's tool ecosystem

If your application demands the absolute highest quality output and you're willing to pay 2x for it, GPT-5.5 justifies the premium.

When Sonnet 4.6 Wins: Value and Coding

Claude Sonnet 4.6 is Anthropic's best value proposition in 2026:

• Coding excellence: Widely regarded as the best coding model at its price point. Excels at code generation, refactoring, and debugging
• Extended thinking: Supports extended thinking for complex reasoning tasks — GPT-5.5 uses a different approach
• Same context, lower price: 1M tokens at $3/$15 vs $5/$30. No context sacrifice
• Batch API savings: At $1.50/$7.50 per million tokens via Batch API, it's the cheapest 1M-context model available
• Instruction following: Strong at following complex prompts with many constraints

Cost per Request by Type

Request Type	Avg Tokens (in/out)	Sonnet 4.6	GPT-5.5	Savings
Chat message	500 / 500	$0.009	$0.018	50%
Code generation	1K / 2K	$0.033	$0.065	49%
Document analysis	5K / 1K	$0.030	$0.055	45%
RAG query	3K / 500	$0.017	$0.030	45%
Content generation	500 / 3K	$0.047	$0.093	50%

Across every request type, Sonnet 4.6 is 45-50% cheaper. The savings compound at scale.

The Batch API Angle

Both models offer Batch API at 50% off. But the absolute savings are larger with Sonnet:

Pricing	Sonnet 4.6 Standard	Sonnet 4.6 Batch	GPT-5.5 Standard	GPT-5.5 Batch
Input ($/1M)	$3.00	$1.50	$5.00	$2.50
Output ($/1M)	$15.00	$7.50	$30.00	$15.00

Sonnet 4.6 Batch API output ($7.50) is half the price of GPT-5.5 Batch API output ($15.00). For non-urgent workloads like data processing, content generation, or batch analysis, the savings are even more dramatic.

Budget Alternatives

Neither model is the cheapest option. If cost is your primary concern:

Model	Input ($/1M)	Output ($/1M)	Context	vs Sonnet 4.6
Gemini 2.0 Flash Lite	$0.075	$0.30	1M	97% cheaper
GPT-5 mini	$0.25	$2.00	272K	92% cheaper
DeepSeek V4 Pro	$0.44	$0.87	1M	85% cheaper
Claude Haiku 4.5	$1.00	$5.00	200K	67% cheaper
Gemini 3.1 Pro	$2.00	$12.00	1M	33% cheaper

Gemini 2.0 Flash Lite at $0.075/$0.30 with 1M context is 97% cheaper than Sonnet 4.6. For most workloads, it's worth testing a budget model first before paying for premium-tier capability.