Claude Sonnet 4.5 vs Kimi K3

Claude Sonnet 4.5 at $3.45 in and $17.25 out and Kimi K3 at $3.45 in and $17.25 out — per million tokens, from the same wallet.

Claude Sonnet 4.5

Anthropic

3.1¢

for a client proposal

$3.45 in · $17.25 out / 1M

1M context · released September 2025

Full page →

Kimi K3

Moonshot AI

3.1¢

for a client proposal

$3.45 in · $17.25 out / 1M

1.05M context · released 3 weeks ago

Full page →

Asking all both at once — identical prompt, identical context — costs about $0.06 for a typical client proposal.

At a glance

All 2 cost the same on input.
Largest context: Kimi K3 at 1.05M tokens — about 1,500 pages.

Cost per task

Estimated totals at the rates above. Solid bar is input, lighter bar is output.

Quick code fix

2K in · 500 out

Claude Sonnet 4.5

1.6¢

Kimi K3

1.6¢

Draft a client proposal from notes

5K in · 800 out

Claude Sonnet 4.5

3.1¢

Kimi K3

3.1¢

Context-heavy session (Alyph workspace)

155K in · 4K out

Claude Sonnet 4.5

$0.60

Kimi K3

$0.60

Analyze a 50-page legal contract

35K in · 1K out

Claude Sonnet 4.5

$0.14

Kimi K3

$0.14

Large architecture refactor

250K in · 3K out

Claude Sonnet 4.5

$1.80

Kimi K3

$0.91

Long-context rate applied at this input size.

Solid part of each bar is input tokens, the lighter part is output. Models that don’t fit a task are marked instead of priced.

Cost vs Token Amount

Drag the slider to adjust the split between input and output workload.

80% Input20% Output

Claude Sonnet 4.5

Kimi K3

Adjust the ratio slider to change how output tokens influence the final price for equivalent workloads.

Pricing

Claude Sonnet 4.5

Kimi K3

Input / 1M tokens

$3.45

Output / 1M tokens

$17.25

Cached input / 1M

$0.345

Web search

1.1¢ / search

—

Specs

Claude Sonnet 4.5

Kimi K3

Provider

Anthropic

Moonshot AI

Released

September 2025

3 weeks ago

Context window

1.05M

Max output

64K

—

Input

Text, Images, and Files

Text and Images

Output

Text

Reasoning

Shows its thinking

Knowledge cutoff

2025-01-31

—

Try it with real numbers

2K tokens in · 500 tokens out.

Claude Sonnet 4.5

Anthropic

1.6¢

for this task

44% input · 56% output

Full pricing →

Kimi K3

Moonshot AI

1.6¢

for this task

44% input · 56% output

Full pricing →

All 2, same prompt and context: 3.1¢. That is the entire cost of the comparison.

Your $5 welcome credit covers about 161 of these.

Which should you pick?

For long documents, Kimi K3 has the largest context window here — 1.05M tokens.

On price they are identical: about 3.1¢ for a typical task each.

Or don’t pick. Send the identical prompt to all both, read the answers side by side, and keep the winner. How to run a fair bake-off →

Claude Sonnet 4.5 pricing →Kimi K3 pricing →Add Lyria 3 Clip Preview Add Grok 4.20

Questions, answered

Which is cheaper, Claude Sonnet 4.5 or Kimi K3?

On a typical client proposal (5K tokens in, 800 out) they cost the same — about 3.1¢ each. Compare them on context and capabilities instead.

Which has the largest context window?

Kimi K3 — 1.05M tokens, about 1,500 pages.

Can I run Claude Sonnet 4.5 and Kimi K3 side by side on Alyph?

Yes — that is what Alyph is built for: the identical prompt with identical context to all 2, answers rendered side by side, billed from one wallet. This exact combination costs about $0.06 for a typical task.

Ask both at once

Identical prompt, identical context, answers side by side — about $0.06 for a typical client proposal. Free to start, with $5 of credit.