Claude Haiku 4.5 vs Claude Sonnet 5
Claude Haiku 4.5 and Claude Sonnet 5 are both from Anthropic but built for different jobs. Haiku 4.5 (released Oct 2025) targets speed and cost efficiency; Sonnet 5 (June 2026) targets raw capability with a 1M token context window and selectable reasoning effort up to 'max'. The gap between them shows up in every number: price, context, and every artificial_analysis benchmark. Picking the wrong one either wastes budget or leaves capability on the table.
Spec vs spec
| Spec | Claude Haiku 4.5 | Claude Sonnet 5 |
|---|---|---|
| Context window | 200K | 1M |
| Max output | 64K | 128K |
| Input modalities | text, image, file | text, image, file |
| Output modalities | text | text |
| Released | Oct 15, 2025 | Jun 30, 2026 |
| Reasoning | optional | optional |
Pricing
Per 1M tokens. Provider price plus the flat 3% fee — the sum is what you pay.
anthropic/claude-haiku-4.5
Input · 1M tokens
$1.00 + 3%$1.03
Output · 1M tokens
$5.00 + 3%$5.15
Cache read · 1M tokens
$0.100 + 3%$0.103
Cache write · 1M tokens
$1.25 + 3%$1.29
FEE — FLAT, EVERY MODEL3%
anthropic/claude-sonnet-5
Input · 1M tokens
$2.00 + 3%$2.06
Output · 1M tokens
$10.00 + 3%$10.30
Cache read · 1M tokens
$0.200 + 3%$0.206
Cache write · 1M tokens
$2.50 + 3%$2.58
FEE — FLAT, EVERY MODEL3%
One workload, priced on both
10M input + 2M output tokens at each model's price, flat 3% fee included.
anthropic/claude-haiku-4.5Cheaper
$20.60
$20.00 provider + 3%
anthropic/claude-sonnet-5
$41.20
$40.00 provider + 3%
Pricing math
Provider list price: Haiku 4.5 runs $1.00/M input, $5.00/M output. Sonnet 5 runs $2.00/M input, $10.00/M output — exactly double on both counts (input price ratio: 0.5). On OpenKey, add the flat 3% fee: Haiku 4.5 becomes $1.03/M input and $5.15/M output; Sonnet 5 becomes $2.06/M input and $10.30/M output.
For a concrete workload — 10M input tokens + 2M output tokens — Haiku 4.5 costs $20.00 at provider rates, Sonnet 5 costs $40.00. That's a $20 difference for the exact same workload, before the 3% OpenKey fee is applied on top of either number. If you're batching high volume, low complexity calls, that gap compounds fast.
Coding and agentic performance
This is where the two models diverge most. On artificial_analysis benchmarks, Sonnet 5 scores 71.5 on the coding index versus Haiku 4.5's 43.9, and 46.7 on the agentic index versus Haiku 4.5's 16.4. Overall intelligence index: 53.4 for Sonnet 5, 29.6 for Haiku 4.5. These aren't close margins — Sonnet 5 is roughly 1.6x on coding and nearly 3x on agentic tasks.
Haiku 4.5 does have Design Arena results across categories like codecategories (elo 1164, rank 63), asciiart (elo 1187, rank 30), and website (elo 1164, rank 64) — useful if you're evaluating narrow front-end generation tasks, though no Design Arena data is available yet for Sonnet 5 to compare directly.
Context and long-document work
Sonnet 5 supports a 1,000,000 token context window with 128,000 max output tokens. Haiku 4.5 supports 200,000 tokens context with 64,000 max output — a 5x context gap (context ratio: 0.2 when comparing Haiku to Sonnet). If your workload involves ingesting large codebases, long transcripts, or multi-document retrieval in a single call, Sonnet 5's window is the difference between one request and a chunking pipeline. For chat-length or single-file tasks, Haiku 4.5's 200K is plenty and cheaper per call.
When to pick each
Pick Haiku 4.5 for high-throughput, cost-sensitive workloads: customer support bots, data extraction, simple tool-calling agents, anything where near-frontier is good enough and you're running millions of calls. Pick Sonnet 5 when the task itself is hard: multi-step agentic workflows, large codebase reasoning, or anything where the coding index gap (71.5 vs 43.9) actually changes the output quality. Sonnet 5 also supports selectable reasoning effort (low through max), giving you a dial Haiku 4.5 doesn't expose. Both models run on OpenKey through one API key with the same flat 3% fee on provider pricing, so switching between them is a model-string change, not an integration project.
Which model for which job
| Use case | Pick | Why |
|---|---|---|
| High-volume customer support automation | Claude Haiku 4.5 | Half the input/output price ($1.03/$5.15 vs $2.06/$10.30 on OpenKey) at near-frontier quality |
| Large codebase refactoring or review | Claude Sonnet 5 | 1M token context vs 200K, plus coding index 71.5 vs 43.9 |
| Multi-step autonomous agents | Claude Sonnet 5 | Agentic index 46.7 vs Haiku 4.5's 16.4 — nearly 3x |
| Simple UI/component generation | Claude Haiku 4.5 | Design Arena uicomponent elo 1155 at a fraction of Sonnet 5's cost |
| Ingesting long documents or transcripts in one call | Claude Sonnet 5 | 1,000,000 token context window vs Haiku's 200,000 |
| Cost-capped batch classification jobs | Claude Haiku 4.5 | $20.00 for a 10M-in/2M-out workload vs Sonnet 5's $40.00 |
Questions
- How much more does Claude Sonnet 5 cost than Claude Haiku 4.5?
- Exactly double on both input and output at provider rates: Sonnet 5 is $2.00/M input and $10.00/M output versus Haiku 4.5's $1.00/M and $5.00/M. On a 10M input + 2M output workload, that's $40.00 for Sonnet 5 versus $20.00 for Haiku 4.5.
- Which model has a bigger context window?
- Claude Sonnet 5 supports 1,000,000 tokens of context, five times Haiku 4.5's 200,000 token window. Sonnet 5 also allows up to 128,000 output tokens versus Haiku 4.5's 64,000.
- Is Claude Sonnet 5 actually better at coding?
- Yes, by a wide margin on artificial_analysis benchmarks: Sonnet 5 scores 71.5 on the coding index versus Haiku 4.5's 43.9, and 46.7 on the agentic index versus 16.4. If coding correctness matters more than cost, Sonnet 5 is the clear choice.
- Can I use both models with the same API setup?
- Yes. Both Claude Haiku 4.5 and Claude Sonnet 5 run on OpenKey under one API key, with pricing set at provider list price plus a flat 3% fee — $1.03/$5.15 per M tokens for Haiku 4.5 and $2.06/$10.30 for Sonnet 5.