Project Status: WIP – Initial development is in progress, but there has not yet been a stable, usable release suitable for the public. pyOpenSci Read the Docs PyPI - Version PyPI - Python Version Codecov GitHub Workflow Status Zenodo


We would greatly appreciate you taking the time to fill out the User Experience Survey to help improve sciform.


sciform is used to convert python numbers into strings according to a variety of user-selected scientific formatting options including decimal, binary, fixed-point, scientific and engineering formats. Where possible, formatting follows documented standards such as those published by BIPM or IEC. sciform provides certain options, such as engineering notation, well-controlled significant figure rounding, and separator customization which are not provided by the python built-in format specification mini-language (FSML).


Install the latest stable version from PyPi with:

python -m pip install sciform

or install the latest development version from GitHub with:

python -m pip install git+

sciform is compatible with Python versions >=3.8.


Here we provide a few key usage examples. For many more details see Usage.

sciform provides a wide variety of formatting options which can be controlled when constructing Formatter objects which are then used to format numbers into strings according to the selected options.

>>> from sciform import Formatter
>>> formatter = Formatter(
...     round_mode="dec_place", ndigits=6, upper_separator=" ", lower_separator=" "
... )
>>> print(formatter(51413.14159265359))
51 413.141 593
>>> formatter = Formatter(round_mode="sig_fig", ndigits=4, exp_mode="engineering")
>>> print(formatter(123456.78))

Users can also format numbers by constructing SciNum objects and using string formatting to format the SciNum instances according to a custom FSML.

>>> from sciform import SciNum
>>> num = SciNum(12345)
>>> print(f"{num:!2f}")
>>> print(f"{num:!2r}")

In addition to formatting individual numbers, sciform can be used to format pairs of numbers as value/uncertainty pairs. This can be done by passing two numbers into a Formatter call or by using the SciNum object.

>>> formatter = Formatter(ndigits=2, upper_separator=" ", lower_separator=" ")
>>> print(formatter(123456.654321, 0.00345))
123 456.654 3 ± 0.003 4
>>> formatter = Formatter(ndigits=4, exp_mode="engineering")
>>> print(formatter(123456.654321, 0.00345))
(123.456654321 ± 0.000003450)e+03
>>> num = SciNum(123456.654321, 0.00345)
>>> print(f"{num:!2f}")
123456.6543 ± 0.0034
>>> print(f"{num:!2f()}")

Note that the above examples demonstrate that sciform uses “round-to-even” rounding.

>>> print(f"{SciNum(865):!2}")
>>> print(f"{SciNum(875):!2}")

See Formatting Options, Format Specification Mini-Language for more details and Examples for more examples.

Project Status

sciform adheres to semantic versioning. The major version for sciform is still 0 indicating that sciform is still in the development stage which means there may be backwards-incompatible changes to the interface (e.g. function or object behaviors and names) without a corresponding major version bump. All changes are announced after new releases in the changelog. Backwards incompatible changes are indicated with the [BREAKING] flag.

We are very excited to get your feedback to help stabilize the interface and make sciform a more useful tool. You can provide your feedback on your experience with sciform by filling out the user experience survey. Now is a great time to share your sciform ideas or issues by opening a discussion or issue. If you would like to contribute to sciform then please see How to Contribute.

sciform has undergone peer review by the PyOpenSci community and been accepted into the PyOpenSci ecosystem. You can view the review here.


sciform was heavily motivated by the prefix formatting provided in the prefixed package and the value ± uncertainty formatting in the uncertainties package.

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