Code editing benchmarks for OpenAI’s “1106” models

benchmark results

benchmark results

OpenAI just released new versions of GPT-3.5 and GPT-4, and there’s a lot of interest about their ability to code compared to the previous versions. With that in mind, I’ve been benchmarking the new models.

Aider is an open source command line chat tool that lets you work with GPT to edit code in your local git repo. To do this, aider needs to be able to reliably recognize when GPT wants to edit your source code, determine which files it wants to modify and accurately apply the changes it’s trying to make. Doing a good job on this “code editing” task requires a good LLM, good prompting and a good tool driving the interactions with the LLM.

Aider relies on a code editing benchmark to quantitatively evaluate performance whenever one of these things changes. For example, whenever I change aider’s prompting or the backend which drives LLM conversations, I run the benchmark to make sure these changes produce improvements (not regressions).

The benchmark uses aider to try and complete 133 Exercism Python coding exercises. For each exercise, Exercism provides a starting python file with stubs for the needed functions, a natural language description of the problem to solve and a test suite to evaluate whether the coder has correctly solved the problem.

The benchmark gives aider two tries to complete the task:

  1. On the first try, aider gives GPT the stub code file to edit and the natural language instructions that describe the problem. This reflects how you code with aider. You add your source code files to the chat and ask for changes, which are automatically applied.
  2. If the test suite fails after the first try, aider gives GPT the test error output and asks it to fix the code. Aider supports this sort of interaction using a command like /run pytest to run and share pytest results in the chat with GPT. You can /run whatever tests/linters/etc make sense for your language/framework/situation.

Benchmark results


For now, I have only benchmarked the GPT-4 models using the diff edit method. This is the edit format that aider uses by default with gpt-4.

  • The new gpt-4-1106-preview model seems 2-2.5X faster than the June GPT-4 model.
  • It seems better at producing correct code on the first try. It gets 53% of the coding exercises correct, without needing to see errors from the test suite. Previous models only get 46-47% of the exercises correct on the first try.
  • The new model seems to perform similar (~65%) to the old models (63-64%) after their second chance to correct bugs by reviewing test suite error output.


I benchmarked the GPT-3.5 models with both the whole and diff edit format. None of the gpt-3.5 models seem able to effectively use the diff edit format, including the newest November (1106) model.

The comments below only focus on comparing the whole edit format results:

  • The new gpt-3.5-turbo-1106 model is completing the benchmark 3-4X faster than the earlier GPT-3.5 models.
  • The success rate after the first try of 42% is comparable to the previous June (0613) model. The new November and previous June models are both worse than the original March (0301) model’s 50% result on the first try.
  • The new model’s 56% success rate after the second try seems comparable to the original March model, and somewhat better than the June model’s 50% score.

This is one in a series of reports that use the aider benchmarking suite to assess and compare the code editing capabilities of OpenAI’s GPT models. You can review the other reports for additional information:


Last updated 11/14/23. OpenAI has relaxed rate limits so these results are no longer considered preliminary.