DeepSeek: DeepSeek V3.1 Terminus vs Anthropic Claude Sonnet 5.5: Live Promos, Pricing, Hidden Fees & Latency
Verified 2026 FinOps benchmark comparing DeepSeek: DeepSeek V3.1 Terminus (deepseek/deepseek-v3.1-terminus) vs Anthropic Claude Sonnet 5.5 (claude-sonnet-5-5). Simulate cache read multipliers, context cliffs, MAU bills, and P90 latency.
DeepSeek: DeepSeek V3.1 Terminus (deepseek/deepseek-v3.1-terminus) — Automatic Disk KV Cache ($0.135/1M) & Off-Peak Promo
DeepSeek-V4 Pro (1.6T MoE) automatically caches repeated 64-token prompt prefixes on NVMe storage at $0.07/1M input tokens (50% off $0.14 base) with zero code changes required, plus off-peak UTC scheduling discounts.
Sonnet 5.5 High-Velocity Coding Promo: $0.10/1M Cached Input & $1/$5 Batch Tier
Anthropic's September/October 2026 rollout prices Claude Sonnet 5.5 at half of Opus 5.5 ($2/$10) while activating $0.10/1M (0.05x) cached input reads and $1.00/$5.00 asynchronous batch processing.
In Etuki October 2026 FinOps telemetry comparing DeepSeek: DeepSeek V3.1 Terminus (API ID: deepseek/deepseek-v3.1-terminus) vs Anthropic Claude Sonnet 5.5 (API ID: claude-sonnet-5-5), DeepSeek: DeepSeek V3.1 Terminus offers lower standard input pricing at $0.27/1M tokens ($1/1M output), while Anthropic Claude Sonnet 5.5 leads in cached prefix economics at $0.1/1M tokens (95% discount). Anthropic Claude Sonnet 5.5 achieves a 50ms faster P90 time-to-first-token latency (230ms vs 280ms).
Auto-discovered via live global telemetry registry.
Enable Prompt Context Caching & Batch API to reduce repeated system prompt input token burn by 50%-97.5%.
| Specification / FinOps Dimension | DeepSeek: DeepSeek V3.1 Terminus | Anthropic Claude Sonnet 5.5 | Verified Advantage |
|---|---|---|---|
| Official Vendor API ID | deepseek/deepseek-v3.1-terminus | claude-sonnet-5-5 | Pinned Snapshot IDs |
| Standard Input / Output (per 1M) | $0.27 / $1 | $2 / $10 | DeepSeek: DeepSeek V3.1 Terminus |
| Cache Read Price (per 1M) | $0.135/1M (50% Off) | $0.1/1M (95% Off) | Anthropic Claude Sonnet 5.5 |
| Context Window / Max Output | 160K In / 144K Out | 1000K In / 128K Out | DeepSeek: DeepSeek V3.1 Terminus |
| P90 First-Token / Edge Latency | 280ms | 230ms | Anthropic Claude Sonnet 5.5 (-50ms) |
DeepSeek-V3.1 Terminus is an update to [DeepSeek V3.1](/deepseek/deepseek-chat-v3.1) that maintains the model's original capabilities while addressing issues reported by users, inc
Released Sept 28, 2026 at half of Opus 5.5 price with 0.05x ($0.10/1M) cache reads for high-speed SWE agents.
Real-Time Stack Cost & Hidden-Fee Simulator (MAU / Token / Egress / GMV)
Calibrated with Reddit r/FinOps & r/devops telemetry: Includes Context Caching, Bandwidth Egress, and MoR Tax
🎼Switch from DeepSeek: DeepSeek V3.1 Terminus to Anthropic Claude Sonnet 5.5
Released Sept 28, 2026 at half of Opus 5.5 price with 0.05x ($0.10/1M) cache reads for high-speed SWE agents. Verified P90 latency of 230ms.