# Claude Sonnet 5.5 release · 2026-09-28 · snapshot 2026-10-26

Creator: Anthropic · 5 effort levels

| Effort level | Input modalities | Intelligence | Total cost | E2E | On the frontier today | ID |
|---|---|---|---|---|---|---|
| Claude Sonnet 5.5 (Low, Default Fallback) | Text, Image | 35.90 | $482 | 5.93s | no | `claude-sonnet-5-5-low` |
| Claude Sonnet 5.5 (Medium, Default Fallback) | Text, Image | 40.80 | $622 | 6.13s | no | `claude-sonnet-5-5-medium` |
| Claude Sonnet 5.5 (High, Default Fallback) | Text, Image | 46.80 | $1027 | 16.5s | no | `claude-sonnet-5-5-high` |
| Claude Sonnet 5.5 (Xhigh, Default Fallback) | Text, Image | 51.90 | $2177 | 33.3s | no | `claude-sonnet-5-5-xhigh` |
| Claude Sonnet 5.5 (Max, Default Fallback) | Text, Image | 56.00 | $7260 | 419.6s | no | `claude-sonnet-5-5` |

## Launch day (2026-09-28)

- Reached the frontier: 1 of 5
- Impact (intelligence × log-cost hypervolume gained): 0.09
- Rank: #40 of 46 releases this past year
- Claude Sonnet 5.5 (Low, Default Fallback) missed: 2.0 points below MiMo-V2.6-Flash at 4.40× its cost
- Claude Sonnet 5.5 (Medium, Default Fallback) missed: 5.5 points below MiMo-V2.6-Pro at 3.01× its cost
- Claude Sonnet 5.5 (Xhigh, Default Fallback) missed: 1.7 points below Claude Opus 5.5 (High, Default Fallback) at 1.00× its cost
- Claude Sonnet 5.5 (Max, Default Fallback) missed: 0.0 points below Claude Opus 5.5 (Xhigh, Default Fallback) at 1.79× its cost


> Metrics snapshot: 2026-10-26T09:34:16Z. Intelligence index version: unknown. Release timeline, frontier age, release impact and shakeup cards are reconstructions using one selected snapshot's metrics, not a record of what was known at release. Scores, benchmark cost and derived value may change when the index methodology changes. Source documentation advertises v4.3.2; API correspondence is unverified.