xl-borders 0.1.1

A Python library to build Excel cell borders with simple range syntax, like VBA

xl-borders

A Python library that simplifies applying cell borders to openpyxl worksheets using Excel-style range strings (e.g. "A1:D5"), inspired by VBA's Range.Borders API.

Installation

# pip
pip install xl_borders

# uv
uv add xl_borders

Requires Python 3.13+ and openpyxl.

Quick Start

from openpyxl import Workbook
from xl_borders import set_border

wb = Workbook()
ws = wb.active

# Thin borders on all sides (default)
set_border(ws, "A1:D5")

# Thick red borders everywhere
set_border(ws, "A1:D5", style="thick", color="FF0000")

# Thick outer edges, thin inner grid
set_border(ws, "A1:D5", outline="thick", inside="thin")

# Compact numeric shorthand: thick outer, thin inner grid
set_border(ws, "A1:D5", custom=(3, 3, 3, 3, 1, 1))

# Override a single edge with shorthand (no Side import needed)
set_border(ws, "A1:D5", outline="medium", left=("double", "FF0000"))

wb.save("output.xlsx")

API

set_border(ws, cell_range, **kwargs)

Apply borders to a rectangular cell range.

Positional arguments:

Argument	Type	Description
ws	Worksheet	The openpyxl worksheet to modify.
cell_range	str	Excel-style range string (e.g. "A1:D5", "B2").

Keyword-only arguments (in priority order, lowest to highest):

Layer	Parameter	Type	Description
1	style	str	Base border style for all 6 sides. Default: "thin".
1	color	str | None	Base border color for all sides (hex, e.g. "FF0000").
2	custom	tuple[int, ...] | None	Weight tuple in CSS-like order (see below).
3	outline	str | None	Style for all 4 outer edges.
3	inside	str | None	Style for inner horizontal and vertical lines.
4	horizontal	str | None	Style for top, bottom, and inner horizontal.
4	vertical	str | None	Style for left, right, and inner vertical.
5	left	SideSpec	Left edge (see Side shorthand below).
5	right	SideSpec	Right edge.
5	top	SideSpec	Top edge.
5	bottom	SideSpec	Bottom edge.
5	inner_horizontal	SideSpec	Inner horizontal lines.
5	inner_vertical	SideSpec	Inner vertical lines.

Higher-layer parameters override lower ones. The color param is inherited by all layers unless a side specifies its own color.

Side shorthand (SideSpec)

Individual side parameters (left, right, top, bottom, inner_horizontal, inner_vertical) accept three forms:

Form	Example	Result
str	left="thick"	Side(style="thick"), inherits base color
(str, str) tuple	left=("thick", "FF0000")	Side(style="thick", color="FF0000")
Side	left=Side(style="thick", ...)	Used as-is (full control)

This eliminates the need to import Side for most use cases.

The custom tuple

A compact way to set all 6 border positions with numeric weights:

(top, right, bottom, left, inner_horizontal, inner_vertical)

Weight mapping: 0 = none, 1 = thin, 2 = medium, 3 = thick.

The tuple length must be 4 or 6. A 4-element tuple sets the outer edges only; inner borders default to 0 (none). The base color is applied to all sides created by custom.

# 6-element: thick outer, thin horizontal grid, medium vertical grid
set_border(ws, "A1:D5", custom=(3, 3, 3, 3, 1, 2))

# 4-element: medium outer edges, no inner grid
set_border(ws, "A1:D5", custom=(2, 2, 2, 2))

# With color: all red
set_border(ws, "A1:D5", custom=(3, 3, 3, 3, 1, 1), color="FF0000")

Examples

All borders in one color

set_border(ws, "A1:D5", style="thick", color="0000FF")

Box border (outline only, no inner grid)

set_border(
    ws, "A1:D5",
    outline="medium",
    inner_horizontal=Side(style=None),
    inner_vertical=Side(style=None),
)

Different horizontal and vertical weights

set_border(ws, "A1:D5", horizontal="thin", vertical="thick")

Override a single edge with shorthand

# String shorthand (inherits base color)
set_border(ws, "A1:D5", outline="medium", color="0000FF", left="double")

# Tuple shorthand (own color overrides base)
set_border(ws, "A1:D5", outline="medium", left=("double", "FF0000"))

Using custom with overrides

Higher-priority layers refine on top of custom:

set_border(
    ws, "A1:D5",
    custom=(3, 2, 3, 2, 1, 1),
    color="0000FF",
    left=("double", "FF0000"),  # override left: double red
)

Available border styles

Any style string accepted by openpyxl's Side(style=...):

thin, medium, thick, double, dashed, mediumDashed, dotted, mediumDashDot, dashDot, mediumDashDotDot, dashDotDot, hair, slantDashDot

Development

# Install dependencies
uv sync

# Run tests
uv run pytest Test/ -v

License

MIT - See LICENSE for details.