Claude Sonnet 5.5 Max vs Kimi K3.1 Pro compared

Claude Sonnet 5.5 Max leads the intelligence index 54.5 to 46.5. Claude Sonnet 5.5 Max writes 5 times as fast. Benchmarks, sample bills, speed and a verdict.

Metric	Claude Sonnet 5.5 (Max, Default Fallback)	Kimi K3.1 Pro
Intelligence Index	54.5	46.5
Input price (per 1M tokens)	$2.00	$2.00
Output price (per 1M tokens)	$10.00	$10.00
Output speed (tokens/s)	136	27
Time to first token	6.5 min	3.0s
Release date	2026-09-28	2026-10-23

Metric

Claude Sonnet 5.5 (Max, Default Fallback)

Kimi K3.1 Pro

Intelligence Index

54.5

46.5

Input price (per 1M tokens)

$2.00

Output price (per 1M tokens)

$10.00

Output speed (tokens/s)

136

Time to first token

6.5 min

3.0s

Release date

2026-09-28

2026-10-23

Claude Sonnet 5.5 (Max, Default Fallback) from Anthropic and Kimi K3.1 Pro from Kimi are both tracked in Franklin AI's benchmark catalogue. All numbers are the catalogue's recorded values; nobody ran either model by hand for this page. Claude Sonnet 5.5 Max streams output at about 136 tokens per second, 5 times the rate of Kimi K3.1 Pro.

Claude Sonnet 5.5 Max is the faster writer

Claude Sonnet 5.5 Max generates about 136 tokens per second and Kimi K3.1 Pro about 27 tokens per second. That makes Claude Sonnet 5.5 Max roughly 5 times as fast at writing. Time to first token is 6.5 minutes for Claude Sonnet 5.5 Max and 3.0 seconds for Kimi K3.1 Pro. Claude Sonnet 5.5 Max writes faster once it starts, but Kimi K3.1 Pro's head start is large enough that Kimi K3.1 Pro still finishes first at any typical reply length; Claude Sonnet 5.5 Max only catches up beyond about 13,000 tokens. A first-token wait of that length suits background work better than live conversation.

Add the two numbers up for a 600-token reply and Kimi K3.1 Pro finishes first: 6.6 minutes for Claude Sonnet 5.5 Max, 25 seconds for Kimi K3.1 Pro.

Pricing: no difference

The list prices are $2.00 in and $10.00 out for Claude Sonnet 5.5 Max, and $2.00 in and $10.00 out for Kimi K3.1 Pro, per million tokens. Neither is cheaper; the price sheets match exactly.

When they came out

Claude Sonnet 5.5 Max came first, on September 28, 2026; Kimi K3.1 Pro followed on October 23, 2026. They are effectively contemporaries.

How the intelligence index compares

Claude Sonnet 5.5 Max comes out ahead on the intelligence index, 54.5 to 46.5. A difference this size usually separates one tier of model from the next.

Across the 109 active models with an intelligence score in the catalogue, Claude Sonnet 5.5 Max ranks 9th and Kimi K3.1 Pro ranks 23rd.

Specialist coding and math indexes are missing for both, so treat the overall score as the only capability signal here.

Cost per point of intelligence

A blunt value measure, blended price over intelligence score, puts Claude Sonnet 5.5 Max at $0.073 and Kimi K3.1 Pro at $0.086 per point. Claude Sonnet 5.5 Max scores higher and costs less per point, so on price per point there is nothing to trade off.

Frequently asked questions

Is Kimi K3.1 Pro better than Claude Sonnet 5.5 Max?

Neither wins everywhere: Claude Sonnet 5.5 Max scores higher on the intelligence index, 54.5 to 46.5; their blended prices are about the same; Claude Sonnet 5.5 Max streams output 5 times as fast; and Kimi K3.1 Pro reaches its first token sooner.

Which is cheaper, Claude Sonnet 5.5 Max or Kimi K3.1 Pro?

They cost about the same. Claude Sonnet 5.5 Max lists $2.00 in and $10.00 out per million tokens, and Kimi K3.1 Pro lists $2.00 and $10.00.

Which is faster, Claude Sonnet 5.5 Max or Kimi K3.1 Pro?

Claude Sonnet 5.5 Max generates output faster, at 136 tokens per second against 27 tokens per second. Kimi K3.1 Pro reaches its first token sooner (3.0 seconds against 6.5 minutes). Counting the first-token wait, Kimi K3.1 Pro finishes first for any reply shorter than about 13,000 tokens.

When were Claude Sonnet 5.5 Max and Kimi K3.1 Pro released?

Kimi K3.1 Pro is newer. It was released on October 23, 2026, 25 days after Claude Sonnet 5.5 Max (September 28, 2026).

Where do these numbers come from?

The figures are the recorded benchmark, price and speed data in Franklin AI's model catalogue. This page is written from that data automatically; neither model was tested by hand for it.

Final whistle

In one line: Kimi K3.1 Pro is the stronger all-round pick on this data, while Claude Sonnet 5.5 Max makes sense in narrower cases. Pick Kimi K3.1 Pro if users are waiting on the first word and replies need to finish sooner at typical lengths. Pick Claude Sonnet 5.5 Max if you need the higher overall score (54.5 against 46.5) and you generate very long outputs, beyond about 13,000 tokens.

Where the numbers come from

The scores, speed and prices in this comparison come from independent third-party model evaluations that Franklin AI syncs each day, and the article was written from a snapshot of them. For the latest results, open the Claude Sonnet 5.5 (Max, Default Fallback) and Kimi K3.1 Pro pages. The AI Benchmark methodology explains how that data is collected and shown.