uv vs pip: Which Should You Use in 2026?

uv vs pip compared: speed, lockfiles, Python version management and the uv pip interface. When to switch, when to stay on pip, and how to migrate.

Use uv for new projects, and pip when you only need to install something into an environment that already exists. uv does what pip does and adds the pieces pip leaves to other tools: virtual environments, Python version management and a lockfile. Astral, the company behind it, says it is 10 to 100 times faster than pip.

At a glance

What pip does

pip installs packages from PyPI into whichever environment its Python belongs to. Around it you use other tools: python -m venv to create environments, a version manager such as pyenv to choose a Python, and something like pip-tools to pin dependencies. pip’s own pinning story is newer: the pip documentation describes pip lock, which writes a pylock.toml file, and the command’s help text marks it as experimental. For the wider picture, see Python package managers compared.

What uv adds

uv is a single tool, written in Rust, that covers several of those jobs. Its documentation describes it as a replacement for pip, pip-tools, pipx, poetry, pyenv, twine, virtualenv and more. A project workflow looks like this:

uv init my-app          # create a project
cd my-app
uv add requests         # add a dependency; updates pyproject.toml and uv.lock
uv run my-app           # run the project's command inside its environment
uv python install 3.14  # download a Python version

uv init creates a packaged project with a build system and a src/my_app/ directory, not a loose main.py: the files are pyproject.toml, README.md, .python-version and src/my_app/__init__.py. uv run my-app prints Hello from my-app!. (Before uv 0.12, applications had no build system by default. uv init --no-package still gives that simpler layout, with a main.py in the project root.) requires-python is set from the Python uv finds, and uv add requests records a lower bound, for example requests>=2.34.2, in pyproject.toml and creates .venv and uv.lock.

The lockfile records exact resolved versions for every dependency, so a teammate or a CI job installs the same set. Where the classic pip workflow uses a flat requirements.txt, uv’s project workflow keeps declared dependencies in pyproject.toml and resolved versions in uv.lock.

The drop-in route

uv’s pip interface mirrors the commands you know:

uv venv
uv pip install -r requirements.txt
uv pip freeze

That is the lowest-risk migration: same files, same commands. uv’s documentation says that swapping pip install for uv pip install should “just work” in most cases, but that uv is not intended to be an exact clone of pip. The differences it documents include:

• A virtual environment is required by default. Without one, uv pip install stops with an error saying no virtual environment was found and suggesting uv venv or --system. uv also finds a .venv in the current or a parent directory even if it is not activated.
• Multiple indexes are searched in order. uv takes a package from the first index that has it, instead of picking the best version across all of them, which matters if you use --extra-index-url.
• No bytecode compilation by default. pip writes .pyc files at install time; uv does not unless you pass --compile-bytecode.
• No --user installs.

When pip is still fine

• A quick install into an existing virtual environment.
• A server or container where adding another tool is not worth it.
• Documentation and scripts written for pip that you do not maintain.

When to switch

Switch when you spend time on environment setup, when installs in CI are slow, or when “works on my machine” bugs come from drifting dependency versions. For Docker specifically, see Docker for Python with uv. To compare uv with Poetry and Hatch, see Poetry vs uv vs Hatch.

Migrating an existing project

Checked with uv 0.13.7, starting from a requirements.txt containing requests==2.31.0 and click:

1. Install uv.
2. Create a pyproject.toml with uv init --bare if the project does not have one.
3. Import the requirements with uv add -r requirements.txt. Exact pins are kept, and an unpinned requirement gets a lower bound, so the result is click>=8.5.0 and requests==2.31.0 (the click version will be whatever is current when you run it). uv creates .venv and uv.lock.
4. Commit uv.lock. In CI, replace pip install -r requirements.txt with uv sync --locked, which fails if the lockfile is out of date with pyproject.toml instead of silently updating it.
5. If another tool still needs a requirements.txt, generate one from the lock with uv export --format requirements-txt.