---
title: "Kimi K3 vs GPT-5.6 Sol on DeepSWE: Cost, Coding, and Routing"
description: "GPT-5.6 Sol and Kimi K3 were compared on the DeepSWE software engineering benchmark using 904 graded rollouts across 113 tasks. Sol wins single-shot pass@1 (72.7% vs 68.5%) and reliability (84.5% tasks solved four-for-four versus 76.6%), while Kimi K3 leads pass@4 (89.4% vs 85.8%) with wider coverage at a substantially lower cost—$4.65 per rollout versus Sol’s $8.37, delivering 14.7 solves per $100 against Sol’s 5.3. The two models have a low task correlation of 0.46 and disagree on 18 tasks, enabling a cascade routing strategy that runs Kimi first and escalates to Sol when the test suite rejects the result, achieving 85.6% accuracy, beating both models individually and a perfect one-shot oracle router. Kimi K3 is open-weight and available on Together AI."
---

# Kimi K3 vs GPT-5.6 Sol on DeepSWE: Cost, Coding, and Routing

[Together AI](https://yomu.fyi/company/together-ai) · Jul 26, 2026

**Type:** Benchmark

## Summary

GPT-5.6 Sol and Kimi K3 were compared on the DeepSWE software engineering benchmark using 904 graded rollouts across 113 tasks. Sol wins single-shot pass@1 (72.7% vs 68.5%) and reliability (84.5% tasks solved four-for-four versus 76.6%), while Kimi K3 leads pass@4 (89.4% vs 85.8%) with wider coverage at a substantially lower cost—$4.65 per rollout versus Sol’s $8.37, delivering 14.7 solves per $100 against Sol’s 5.3. The two models have a low task correlation of 0.46 and disagree on 18 tasks, enabling a cascade routing strategy that runs Kimi first and escalates to Sol when the test suite rejects the result, achieving 85.6% accuracy, beating both models individually and a perfect one-shot oracle router. Kimi K3 is open-weight and available on Together AI.

## Context

The post evaluates two large language models on the DeepSWE software engineering benchmark, comparing single-shot and multi-shot accuracy, cost, and the benefits of routing between them.

## Approach / What changed

A cascade routing strategy where Kimi K3 is attempted first; if its output fails the test suite, the task is escalated to GPT-5.6 Sol. This approach yields 85.6% accuracy at a cost lower than using Sol alone.

## Takeaways

- On DeepSWE, GPT-5.6 Sol achieves a higher single-shot pass@1 (72.7%) than Kimi K3 (68.5%), but Kimi K3 wins on pass@4 (89.4% vs 85.8%) due to wider coverage across multiple attempts.
- Kimi K3 costs $4.65 per rollout versus Sol’s $8.37, delivering 2.8 times more solved tasks per dollar, making it the stronger value for high-volume or retry-tolerant agent work.
- The two models have low task-level correlation (0.46), so routing a Kimi-first cascade that escalates to Sol on test failure achieves 85.6% accuracy, outperforming either model alone and cheaper per solve than Sol.

## FAQ

### Is Kimi K3 better than GPT-5.6 Sol?

It depends on the metric. GPT-5.6 Sol wins single-attempt quality with pass@1 72.7% vs 68.5% and solves more tasks four-for-four. Kimi K3 wins pass@2 and pass@4 and costs far less, so it is the stronger value for high-volume or retry-tolerant work. For most teams, routing between them is best.

### How much cheaper is Kimi K3 than GPT-5.6 Sol?

Kimi K3 costs $4.65 per rollout versus Sol's $8.37, a little over half the price. Per solved task, Kimi K3 returns 14.7 solves per $100 against Sol's 5.3, about 2.8 times the work per dollar.

### How high can routing between them get you?

With a Kimi-first cascade that uses a test suite as verifier, routing achieves about 85.6% accuracy on DeepSWE. This beats either model alone (Sol's 72.7% or Kimi's 68.5% pass@1) and even a perfect one-shot oracle router (83.4%), because the cascade gives hard tasks two independent attempts.

**Tags:** [Cost Optimization](https://yomu.fyi/topic/cost-optimization), [DeepSWE](https://yomu.fyi/topic/deepswe), [GPT-5.6 Sol](https://yomu.fyi/topic/gpt-5-6-sol), [Kimi K3](https://yomu.fyi/topic/kimi-k3), [Model Routing](https://yomu.fyi/topic/model-routing)

- Source: [Together AI](https://www.together.ai/blog/kimi-k3-vs-gpt-5-6-sol-on-deepswe-cost-coding-and-routing)
- Source URL: https://www.together.ai/blog/kimi-k3-vs-gpt-5-6-sol-on-deepswe-cost-coding-and-routing
- Ingested by Yomu: 2026-09-19T10:13:42.792Z

[Read original post](https://www.together.ai/blog/kimi-k3-vs-gpt-5-6-sol-on-deepswe-cost-coding-and-routing)