---
title: "OpenAI: GPT-6 far better at COBOL, Fortran and other legacy languages"
url: https://www.parallelquant.com/posts/openai-gpt-6-far-better-at-cobol-fortran-and-other-legacy-languages-76e236
source_name: "The Decoder"
source_url: https://the-decoder.com/openai-says-gpt-6-is-much-better-with-legacy-programming-languages-such-as-cobol-and-fortran/
published: 2026-10-20T16:40:29.000Z
topics: ["llms", "products"]
publisher: "Parallel Quant"
---

# OpenAI: GPT-6 far better at COBOL, Fortran and other legacy languages

*2026-10-20 · Source: [The Decoder](https://the-decoder.com/openai-says-gpt-6-is-much-better-with-legacy-programming-languages-such-as-cobol-and-fortran/)*

On OpenAI's new MultiLangBench, GPT-6 Astra passes 87.4% of tests across 20 languages, up from about 38% for GPT-5.6 Terra. For COBOL migration, GPT-6.1 Sol reaches up to 97.9% accuracy.

**Why it matters:** Legacy code in COBOL and similar languages underpins banks and governments, and migration has been held back by scarce expertise. These are vendor-reported numbers on a new benchmark, but if they hold, modernization becomes a realistic AI workload.

**Topics:** llms, products

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Read the original: https://the-decoder.com/openai-says-gpt-6-is-much-better-with-legacy-programming-languages-such-as-cobol-and-fortran/
Canonical: https://www.parallelquant.com/posts/openai-gpt-6-far-better-at-cobol-fortran-and-other-legacy-languages-76e236
Published by Parallel Quant — https://www.parallelquant.com