The Linux kernel reached 40 million lines of code in January 2025 with kernel 6.14 rc1, doubling its size since 2015. The 2025 development cycle saw 2,134 developers contribute to kernel 6.18, marking the highest participation in the project’s history. This analysis examines verified statistics on codebase growth, contributor engagement, and corporate investment in the world’s largest open-source project.
Linux Kernel Key Statistics
- The Linux kernel contains 40,063,856 lines of code as of January 2025
- Kernel 6.18 attracted 2,134 developers in 2025, the highest contributor count ever recorded
- Intel leads corporate contributions with nearly double the changesets of second-place Google
- The kernel adds approximately 400,000 lines of code every two months
- Over 1,780 organizations contributed to the Linux kernel in 2025
Linux Kernel Lines of Code Growth
The Linux kernel crossed the 40 million line threshold with version 6.14 rc1 in January 2025, containing precisely 40,063,856 lines. This represents exponential growth from the original 10,239 lines in version 0.01 released in 1991.
The codebase has doubled over the past decade. In 2015, kernel 4.1 contained approximately 19 million lines. By December 2024, kernel 6.12 reached 39,819,522 lines before surpassing 40 million the following month.
Development activity in 2024 added 3,694,098 lines while removing 1,490,601 lines, producing net growth of 2.2 million lines. The kernel grows at an average rate of 400,000 lines every two months, driven by hardware support expansion, security enhancements, and driver additions.
| Year | Kernel Version | Total Lines of Code |
|---|---|---|
| 1991 | 0.01 | 10,239 |
| 1994 | 1.0.0 | 170,000+ |
| 2015 | 4.1 | 19,000,000+ |
| 2024 | 6.12 | 39,819,522 |
| 2025 | 6.14 rc1 | 40,063,856 |
Linux Kernel Developer Contributions in 2025
Kernel 6.18, released on November 30, 2025, established a new record with 2,134 developers contributing to a single release. This surpassed the previous record of 2,090 developers set during kernel 6.2 in 2023.
The complete 2025 LTS cycle spanning kernels 6.12 through 6.18 included six releases with 80,035 total changesets from 5,275 unique developers. This compares to the previous LTS cycle (6.6 to 6.12) which incorporated 86,715 changesets from 5,111 developers.
First-time contributors remained strong throughout 2025. Kernel 6.12 attracted 335 first-time contributors, while kernel 6.18 brought in 333 new developers. Kernel 6.14 saw the lowest number with 228 first-time participants.
Top Individual Contributors
Kent Overstreet led individual contributions with nearly 4,000 commits in 2024, primarily focused on the Bcachefs filesystem. Uwe Kleine-König from Pengutronix contributed over 1,000 commits for platform driver API refactoring.
Linus Torvalds contributed 2,877 commits in 2024, mainly merge operations. Greg Kroah-Hartman continues as the most active maintainer, handling stable releases and multiple driver subsystems across the development cycle.
| Developer | Affiliation | Focus Area |
|---|---|---|
| Kent Overstreet | Independent | Bcachefs filesystem |
| Uwe Kleine-König | Pengutronix | Platform driver API |
| Krzysztof Kozlowski | Linaro | Devicetree changes |
| Takashi Iwai | SUSE | Sound subsystem |
| Thomas Weißschuh | Independent | Kernel hardening |
Linux Kernel Corporate Contributors
Corporate developers authored 84.3% of kernel commits in 2025, with contributions distributed across more than 1,780 organizations. Intel maintained its position as the top contributor by changesets, delivering nearly double the volume of second-place Google.
Google demonstrated extensive sign-off activity, accounting for approximately 12.5% of patches. Meta functions as a significant maintainer hub, with 12.5% of patches passing through Meta-affiliated reviewers.
AMD concentrated efforts on GPU drivers, particularly amdgpu register definitions. Red Hat focused on core kernel and enterprise features, while Linaro specialized in ARM architecture support. Huawei maintained consistent top-5 contributor status throughout the development cycle.
Oracle achieved top-5 placement for core kernel contributions (fs/, mm/, kernel/ paths) across kernels 6.2 through 6.15, claiming first place in versions 6.4, 6.10, and 6.13 with contribution shares between 12.3% and 17.3%.
Linux Kernel Release Statistics
The 2024-2025 development period showed variance in release intensity. Kernel 6.14 marked the slowest cycle since Linux 4.0 in 2015 with only 11,003 changesets, while kernel 6.15 rebounded to become the busiest release since 6.7 with 14,612 changesets.
Total commits across all 2024 releases reached 75,314, down from 87,993 in 2023. Despite the reduced commit count representing the lowest annual engagement in a decade, this reflected larger and more substantive commits rather than declining activity.
| Kernel Version | Release Date | Changesets | Developers |
|---|---|---|---|
| 6.12 (LTS) | Nov 2024 | 13,344 | 2,074 |
| 6.13 | Jan 2025 | 12,928 | 2,001 |
| 6.14 | Mar 2025 | 11,003 | 1,897 |
| 6.15 | May 2025 | 14,612 | 2,068 |
| 6.18 (LTS) | Nov 2025 | 13,710 | 2,134 |
Code review participation increased in 6.18, with 49.2% of commits including Reviewed-by tags and 9.3% including Tested-by tags. Daniel Wheeler from AMD has maintained the top tester position since kernel 6.3.
Linux Kernel Code Distribution by Subsystem
Device drivers comprise approximately 60% of the kernel’s 40 million lines, making them the largest component by far. Network drivers, GPU drivers, and multimedia drivers constitute the three largest driver categories within this subsystem.
Architecture-specific code accounts for roughly 15% of the codebase with over 4.5 million lines supporting x86, ARM, RISC-V, PowerPC, and other platforms. File systems occupy 8% of the code, while networking components represent 7%.
The core kernel components including memory management and process scheduling comprise only 5% of the total codebase. Documentation and other miscellaneous elements make up the remaining 5% of the 40 million line total.
FAQs
How many lines of code does the Linux kernel have?
The Linux kernel contains 40,063,856 lines of code as of January 2025 with kernel 6.14 rc1. This represents a doubling from approximately 20 million lines in 2015.
How many developers contribute to the Linux kernel?
Kernel 6.18 attracted 2,134 developers in 2025, the highest participation ever recorded. The complete 2025 LTS cycle included 5,275 unique developers across six releases.
Which company contributes most to Linux kernel development?
Intel leads corporate contributions with nearly double the changesets of second-place Google during the 2025 LTS cycle. Over 1,780 organizations contributed to the kernel in 2025.
What percentage of Linux kernel is device drivers?
Device drivers comprise approximately 60% of the Linux kernel codebase. Network drivers, GPU drivers, and multimedia drivers represent the three largest driver categories.
How fast is the Linux kernel growing?
The kernel adds approximately 400,000 lines of code every two months. In 2024, developers added 3,694,098 lines and removed 1,490,601 lines for net growth of 2.2 million lines.
