Kimi K2.5 vs Kimi K3
Kimi K2.5 (Azure AI Foundry, 262,144-token context) versus Kimi K3 (Moonshot AI, 1,048,576-token context). Kimi K2.5 is cheaper by 80% on a blended token mix. Kimi K2.5 uniquely supports vision input. Kimi K3 uniquely supports prompt caching and native reasoning mode. Across 1 public benchmark we tracked, Kimi K2.5 wins 0 and Kimi K3 wins 1. Use the live calculator below to plug your real usage shape into both, then route the winner via Agent Command Center for shadow A/B without code changes.
Bottom line — Kimi K2.5 vs Kimi K3
Kimi K2.5 and Kimi K3 target overlapping workloads but differ sharply on economics. Kimi K2.5 runs roughly 80% cheaper on a blended input-plus-output token mix, which translates to approximately $14,400 per month at mid-market volume (100K requests/day). The gap compounds at enterprise scale, making the cost axis the first filter most teams apply when deciding between these two models.
Kimi K3 ships a 1,048,576-token context window, 4.0x larger than Kimi K2.5's 262,144 tokens. That headroom matters for long-document RAG pipelines, multi-turn agent sessions that accumulate tool-call history, and codebases where the entire repository needs to fit in a single prompt. If your average prompt stays under 262,144 tokens, the extra context on Kimi K3 is insurance you may never use — and Kimi K2.5 may win on other axes.
On capability surface area, the models diverge: Kimi K2.5 supports vision input where the other does not; Kimi K3 supports prompt caching where the other does not; Kimi K3 supports native reasoning mode where the other does not. These differences are binary — either your workload needs the capability or it does not. Check whether any critical path in your agent pipeline depends on a capability only one model provides before committing to a migration.
For teams evaluating both models, the recommended path is a shadow A/B test: route production traffic through an OpenAI-compatible gateway, mirror a percentage to the candidate model, score both responses with an automated evaluator (faithfulness, tool-call correctness, latency), and compare cohort-level metrics over two weeks. Future AGI Agent Command Center supports this pattern with a single `base_url` change and built-in evaluators from the ai-evaluation SDK.
Live workload comparison
Same workload run through both models. The cheaper one is highlighted.
strategy: cost-optimized
primary:
model: kimi-k2-5
provider: azure-ai-foundry
fallback:
model: kimi-k3
provider: moonshot
shadow: { sample_rate: 0.05 } # mirror 5% of traffic to compare quality live| Kimi K2.5 | Kimi K3 | |
|---|---|---|
| Input price | $0.600/M | $3.00/M |
| Output price | $3.00/M | $15.00/M |
| Context window | 262,144 | 1,048,576 |
| Max output | 262,144 | 1,048,576 |
| Function calling | ✓ | ✓ |
| Vision | ✓ | — |
| Audio input | — | — |
| Reasoning | — | ✓ |
| Prompt caching | — | ✓ |
| Structured output | — | — |
| Pricing verified | Aug 6, 2026 | Aug 6, 2026 |
Benchmark comparison
Side-by-side public benchmark scores. Greener bar = winner.
Cost at scale: monthly spend at three usage volumes
Estimated monthly cost assuming 1,000 input + 200 output tokens per request — a realistic chat-agent shape. Adjust your own usage in the calculator at the top of this page for an exact number.
| Scale | Kimi K2.5 | Kimi K3 | Delta |
|---|---|---|---|
| Startup 10K requests/day | $360 /mo | $1,800 /mo | $1,440/mo |
| Mid-market 100K requests/day | $3,600 /mo | $18,000 /mo | $14,400/mo |
| Enterprise 1M requests/day | $36,000 /mo | $180,000 /mo | $144,000/mo |
At enterprise scale (1M requests/day), a difference of even ~10% in unit price compounds into thousands of dollars per month. Cached input pricing and batch tiers can shift this further — both are surfaced on each model's own page.
When to choose which
Picked from the data above — not vendor marketing. Match the rules to your workload, not the other way around.
You're cost-sensitive at scale — Kimi K2.5 runs ~80% cheaper on a blended in+out token mix, compounding into thousands of dollars per month at production volume.
Your workload needs long context — Kimi K3 fits 1,048,576 tokens versus the other model's 262,144, enough headroom for full books, large codebases, or 100+ page documents in one shot.
Your inputs include screenshots, diagrams, or product photos — Kimi K2.5 accepts image input natively, the other doesn't.
Your tasks involve multi-step planning or math-heavy reasoning — Kimi K3 ships a native reasoning mode that explicitly thinks before responding, the other doesn't.
You re-send the same large system prompt across requests — Kimi K3 supports prompt caching, cutting input cost on repeat hits.
On arena-elo, Kimi K3 scores 36.0 points higher — if your workload pattern matches that benchmark's task shape, the gap is meaningful.
Capability diff — what you gain and lose on the swap
A specific list of what each model has that the other doesn't. If your workload depends on a row in Only Kimi K2.5, switching to Kimi K3 means re-architecting that path (and vice versa).
- • Vision input
- • Prompt caching
- • Native reasoning mode
Capabilities both share (2)
- ✓ Function calling
- ✓ Streaming
Benchmark winners — by the numbers
For each public benchmark that has scores for both models, the higher score and the size of the gap. Benchmarks are noisy — treat anything under a 2-point delta as effectively tied.
| Benchmark | Kimi K2.5 | Kimi K3 | Winner | Δ |
|---|---|---|---|---|
| arena-elo | 1449.0 | 1485.0 | Kimi K3 | +36.0 |
Migration considerations
Concrete differences to wire through your stack before you flip traffic from one to the other.
- Context window changes up 300% when moving from Kimi K2.5 (262,144) to Kimi K3 (1,048,576). Re-check any prompt that relies on cramming long history or documents.
- Max output tokens differ: 262,144 on Kimi K2.5 vs 1,048,576 on Kimi K3. Long-form generation tasks may truncate differently — adjust streaming UI and chunking accordingly.
- Kimi K2.5 has capabilities Kimi K3 lacks: Vision input. Switching to Kimi K3 means re-architecting any flow that depends on these.
- Kimi K3 has capabilities Kimi K2.5 lacks: Prompt caching, Native reasoning mode. Worth wiring through the agent design before commit.
- Provider changes from Azure AI Foundry to Moonshot AI. API authentication, rate-limit policy, regional availability, and billing all shift. Most teams route through an OpenAI-compatible gateway (e.g., Future AGI Agent Command Center) so the swap is a single `base_url` change instead of an SDK rewrite.
How to A/B test Kimi K2.5 vs Kimi K3 in production
If you're stuck between the two, run them side-by-side on real traffic. Four steps the Future AGI team uses internally:
- 1. Point your existing OpenAI SDK at
https://gateway.futureagi.com/v1. No code change beyondbase_urland a virtual key. - 2. Mark Kimi K2.5 primary, mirror 20% of traffic to Kimi K3 in shadow mode. Both responses are logged; only the primary is served to users.
- 3. Score every shadow response with an evaluator — faithfulness, tool-call correctness, response latency, cost. Built-in evaluators in ai-evaluation cover the common axes.
- 4. Compare cohort-level metrics after two weeks. Switch primary when the candidate wins on what matters to your workload — and stays within your latency budget.
Full walkthrough on the Agent Command Center page.
FAQ — Kimi K2.5 vs Kimi K3
Which is cheaper, Kimi K2.5 or Kimi K3? ▾
Kimi K2.5 is cheaper by roughly 80% on a blended input + output token mix. Input prices are $0.600/M for Kimi K2.5 versus $3.00/M for Kimi K3; output prices are $3.00/M versus $15.00/M. The exact savings depend on your input:output ratio — use the live calculator above to plug in your own request shape.
What is the context window of Kimi K2.5 versus Kimi K3? ▾
Kimi K2.5 supports up to 262,144 tokens of context. Kimi K3 supports up to 1,048,576 tokens. Kimi K3 has the larger window by a factor of 4.0x, which matters for long-document RAG, multi-turn agent sessions, and tasks that need to keep an entire codebase in working memory.
Do Kimi K2.5 and Kimi K3 both support tool calling? ▾
Yes — both Kimi K2.5 and Kimi K3 support native function calling. Both also support structured output via JSON schema, so an agent can be ported between them with the same tool definitions.
Can Kimi K2.5 and Kimi K3 process images? ▾
Kimi K2.5 accepts native image input. Kimi K3 does not — you would need to route image-heavy workloads through Kimi K2.5 or add a separate vision model in front of Kimi K3.
Which model supports prompt caching for cost reduction? ▾
Kimi K3 supports prompt caching; the other does not. If your agent has a stable system prompt + retrieval context block that repeats across requests, Kimi K3 gives you a 50–90% discount on those repeated input tokens at the provider level.
When should I choose Kimi K2.5 over Kimi K3? ▾
You're cost-sensitive at scale — Kimi K2.5 runs ~80% cheaper on a blended in+out token mix, compounding into thousands of dollars per month at production volume. Your inputs include screenshots, diagrams, or product photos — Kimi K2.5 accepts image input natively, the other doesn't.
When should I choose Kimi K3 over Kimi K2.5? ▾
Your workload needs long context — Kimi K3 fits 1,048,576 tokens versus the other model's 262,144, enough headroom for full books, large codebases, or 100+ page documents in one shot. Your tasks involve multi-step planning or math-heavy reasoning — Kimi K3 ships a native reasoning mode that explicitly thinks before responding, the other doesn't. You re-send the same large system prompt across requests — Kimi K3 supports prompt caching, cutting input cost on repeat hits. On arena-elo, Kimi K3 scores 36.0 points higher — if your workload pattern matches that benchmark's task shape, the gap is meaningful.
How do I A/B test Kimi K2.5 against Kimi K3 in production? ▾
Route both through an OpenAI-compatible gateway like Future AGI Agent Command Center with shadow mode enabled. Send 100% of traffic to your primary model, mirror 10–20% to the candidate, score every response with an evaluator (faithfulness, tool-call correctness, response time), and compare cohort-level metrics for two weeks. Switch when the candidate wins on the metrics that matter to your workload and stays within your latency budget.