Kimi K3.1 Pro vs Claude Opus 5.5
Official Kimi and Anthropic API prices and LMArena scores, checked 2026-10-29. Add up to 2 more models to compare 4.
Kimi K3.1 Pro costs less; Claude Opus 5.5 wins more LMArena tasks.
Kimi K3.1 Pro is 2x cheaper on input and output. Claude Opus 5.5 scores 43 points higher for coding. Across 1 shared LMArena task, Claude Opus 5.5 leads 1 to 0. A medium month (20M input + 5M output tokens) costs $90 on Kimi K3.1 Pro and $180 on Claude Opus 5.5.
- Pick Kimi K3.1 Pro if you want the lower bill ($90 vs $180 for a medium month).
- Pick Claude Opus 5.5 if you care most about coding (+43).
Medium: 20M input + 5M output tokens a month at list price (short-context rate, no caching or batch discounts).
Marked side is better: lower for prices, higher for context and scores. Bars are scaled to the larger of the two.
| Spec | Kimi K3.1 Pro | Claude Opus 5.5 |
|---|---|---|
| Price per 1M tokens | ||
| Input | $2 | $4 |
| Cached input | $0.20 | $0.20 |
| Output | $10 | $20 |
| Blend 3:1 | $4 | $8 |
| Sample month, medium | $90 | $180 |
| Context | ||
| Context window | 1.04858M tokens | 1M tokens |
| Quality (LMArena, out of 100) | ||
| Coding | 57/100 #6 of 50 | 100/100 #1 of 50 |
| Chat | Not ranked | 78/100 #2 of 51 |
| Creative writing | Not ranked | 100/100 #1 of 51 |
| Roleplay and characters | Not ranked | 37/100 #5 of 51 |
| Reasoning and math | Not ranked | 64/100 #5 of 51 |
| Vision | Not ranked | 84/100 #3 of 33 |
| Long documents | Not ranked | Not ranked |
| Cheap bulk and agents | Not ranked | 100/100 #1 of 34 |
| Details | ||
| Provider | Kimi | Anthropic |
| API model id | kimi-k3.1-pro | claude-opus-5.5 |
| Notes | Flat price across the 1M window. Cache writes cost $2 (5-minute) or $4 (1-hour). | 5-minute cache writes $5. |
| Sources | ||
| Last checked | 2026-10-29 | 2026-10-29 |
| Official pricing | Kimi pricing | Anthropic pricing |
Plans from data checked hourly against each vendor's official pricing page. Vendors state limits in different units, so we quote them as published. Team and enterprise plans are per seat.
API prices in USD per 1M tokens from each provider's official pricing page. Blend 3:1 = (3 x input + output) / 4. Sample month = stated input and output tokens at the list price, no caching. Quality: relative score out of 100 on each LMArena leaderboard (100 = top model we price on that board, n/a = not ranked there), data licensed CC BY 4.0. See how we pick.
Where each one ranks on LMArena
Relative score out of 100 on each leaderboard (100 = the top model we price there), with the rank among the models from our API price table that appear on that board.
- Coding (Code Arena): Kimi K3.1 Pro #6 of 50 (57/100), Claude Opus 5.5 #1 of 50 (100/100)
- Chat (Text Arena): Kimi K3.1 Pro not ranked, Claude Opus 5.5 #2 of 51 (78/100)
- Creative writing (Text Arena creative writing): Kimi K3.1 Pro not ranked, Claude Opus 5.5 #1 of 51 (100/100)
- Roleplay and characters (Text Arena multi-turn): Kimi K3.1 Pro not ranked, Claude Opus 5.5 #5 of 51 (37/100)
- Reasoning and math (Text Arena math): Kimi K3.1 Pro not ranked, Claude Opus 5.5 #5 of 51 (64/100)
- Vision (Vision Arena): Kimi K3.1 Pro not ranked, Claude Opus 5.5 #3 of 33 (84/100)
- Long documents (Document Arena): Kimi K3.1 Pro not ranked, Claude Opus 5.5 not ranked
- Cheap bulk and agents (Agent Arena): Kimi K3.1 Pro not ranked, Claude Opus 5.5 #1 of 34 (100/100)
Pricing details from the official pages
Kimi K3.1 Pro lists $2 input, $10 output, $0.20 cached input per 1M tokens on Kimi pricing. Claude Opus 5.5 lists $4 input, $20 output, $0.20 cached input per 1M tokens on Anthropic pricing. Prices checked 2026-10-29.
- Kimi K3.1 Pro: Flat price across the 1M window. Cache writes cost $2 (5-minute) or $4 (1-hour).
- Claude Opus 5.5: 5-minute cache writes $5.
Sample monthly bill at list price, no caching: Light (2M input + 0.5M output tokens): $9 vs $18. Medium (20M input + 5M output tokens): $90 vs $180. Heavy (200M input + 50M output tokens): $900 vs $1,800.
FAQ
Is Kimi K3.1 Pro cheaper than Claude Opus 5.5?
Kimi K3.1 Pro costs $2 input and $10 output per 1M tokens; Claude Opus 5.5 costs $4 and $20. For a medium month (20M input + 5M output tokens) Kimi K3.1 Pro is cheaper: $90 vs $180.
Which is better for coding, Kimi K3.1 Pro or Claude Opus 5.5?
On LMArena's Code Arena Kimi K3.1 Pro scores 57/100 (#6 of 50) and Claude Opus 5.5 100/100 (#1 of 50), so Claude Opus 5.5 is ahead by 43 points.
Which has the bigger context window?
Kimi K3.1 Pro: 1.04858M tokens. Claude Opus 5.5: 1M tokens.
How much do Kimi K3.1 Pro and Claude Opus 5.5 cost per month?
Light (2M input + 0.5M output tokens): $9 vs $18. Medium (20M input + 5M output tokens): $90 vs $180. Heavy (200M input + 50M output tokens): $900 vs $1,800. Pick your own token counts in the plan vs API calculator.
Where do these numbers come from?
Prices come from each provider's official pricing page, checked daily. Quality is the relative score on the LMArena leaderboard dataset, licensed CC BY 4.0. Where a model is not ranked we show n/a.
Sources
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