Claude Sonnet 5 vs DeepSeek V4 Flash
Pricing, benchmarks, and use case comparison
Quick take
- •Claude Sonnet 5 is meaningfully stronger at multimodal (85 vs 10 on our capability index).
- •DeepSeek V4 Flash is meaningfully stronger at cost efficiency (95 vs 85).
- •DeepSeek V4 Flash is open-weights (free to self-host); Claude Sonnet 5 is paid API only.
Specs comparison
| Claude Sonnet 5 | DeepSeek V4 Flash | |
|---|---|---|
| Provider | Anthropic | DeepSeek |
| Type | Closed source | Open source |
| Context window | 1M | 1M tokens |
| Input / 1M tokens | $3.00 | ✓Free (self-host) |
| Output / 1M tokens | $15.00 | Free (self-host) |
| Release date | 2026-06 | 2026-04 |
Benchmarks
| Benchmark | Claude Sonnet 5 | DeepSeek V4 Flash |
|---|---|---|
| SWE-bench Verified | ~85.2% | - |
| Terminal-Bench 2.1 | 80.4% | - |
| SWE-bench Pro | 63.2% | - |
| OSWorld-Verified | 81.2% | - |
| Reasoning (vs V4 Pro) | - | Closely approaches V4 Pro |
Scores sourced from official provider release posts and independent benchmark aggregators.
Which should you choose?
Choose Claude Sonnet 5 if...
- →You want frontier-adjacent agentic coding but need better cost-efficiency than Opus
- →You are running high-volume agent loops and want strong reasoning per dollar
- →You are already on Sonnet 4.6 and want a same-price capability upgrade
- →You need a 1M context window with fast latency
Choose DeepSeek V4 Flash if...
- →You want most of V4 Pro's capability at a lower price and higher throughput
- →You need long context but on a tighter compute or cost budget
- →You are serving high request volumes where per-token cost dominates
- →You want an open model small enough to self-host on modest multi-GPU setups