Setting styles in Openpyxl

As of openpyxl-1.7.0 you can do this too:

cell.style.fill.start_color.index = "FF124191"

I’ve got a couple of helper functions which set a style on a given cell – things like headers, footers etc.

As of openpyxl 2.0, styles are immutable.

If you have a cell, you can (e.g.) set bold text by:

cell.style = cell.style.copy(font=cell.style.font.copy(bold=True))

Yes, this is annoying.

As of openpyxl 2.0, setting cell styles is done by creating new style objects and by assigning them to properties of a cell.

There are several style objects: Font, PatternFill, Border, and Alignment. See the doc.

To change a style property of a cell, first you either have to copy the existing style object from the cell and change the value of the property or you have to create a new style object with the desired settings. Then, assign the new style object to the cell.

Example of setting the font to bold and italic of cell A1:

from openpyxl import Workbook
from openpyxl.styles import Font
# Create workbook
wb = Workbook()
# Select active sheet
ws = wb.active()
# Select cell A1
cell = ws['A1']
# Make the text of the cell bold and italic
cell.font = cell.font.copy(bold=True, italic=True)

Like openpyxl doc said:

This is an open source project, maintained by volunteers in their spare time. This may well mean that particular features or functions that you would like are missing.

I checked openpyxl source code, found that:

Till openpyxl 1.8.x, styles are mutable. Their attribute can be assigned directly like this:

from openpyxl.workbook import Workbook
from openpyxl.style import Color

wb = Workbook()
ws = wb.active
ws['A1'].style.font.color.index = Color.RED

However from of openpyxl 1.9, styles are immutable.

Styles are shared between objects and once they have been assigned they cannot be changed. This stops unwanted side-effects such as changing the style for lots of cells when instead of only one.

To create a new style object, you can assign it directly, or copy one from an existing cell’s style with new attributes, answer to the question as an example(forgive my Chinese English):

from openpyxl.styles import colors
from openpyxl.styles import Font, Color
from openpyxl import Workbook
wb = Workbook()
ws = wb.active

a1 = ws['A1']
d4 = ws['D4']

# create a new style with required attributes
ft_red = Font(color=colors.RED) 
a1.font = ft_red

# you can also do it with function copy
ft_red_bold = ft_red.copy(bold=True)

# you can copy from a cell's style with required attributes
ft_red_sigle_underline = a1.font.copy(underline="single")

d4.font = ft_red_bold

# apply style to column E
col_e = ws.column_dimensions['E']
col_e.font = ft_red_sigle_underline

A cell’ style contains these attributes: font, fill, border, alignment, protection and number_format. Check openpyxl.styles.

They are similar and should be created as an object, except number_format, its value is string type.

Some pre-defined number formats are available, number formats can also be defined in string type. Check openpyxl.styles.numbers.

from openpyxl.styles import numbers

# use pre-defined values
ws.cell['T49'].number_format = numbers.FORMAT_GENERAL
ws.cell(row=2, column=4).number_format = numbers.FORMAT_DATE_XLSX15

# use strings
ws.cell['T57'].number_format = 'General'
ws.cell(row=3, column=5).number_format = 'd-mmm-yy'
ws.cell['E5'].number_format = '0.00'
ws.cell['E50'].number_format = '0.00%'
ws.cell['E100'].number_format = '_ * #,##0_ ;_ * -#,##0_ ;_ * "-"??_ ;_ @_ '

For openpyxl version 2.4.1 and above use below code to set font color:

from openpyxl.styles import Font
from openpyxl.styles.colors import Color

ws1['A1'].font = Font(color = "FF0000")

hex codes for various colors can be found at:
http://dmcritchie.mvps.org/excel/colors.htm

This seems like a feature that has changed a few times. I am using openpyxl 2.5.0, and I was able to set the strike-through option this way:

new_font = copy(cell.font)
new_font.strike = True
cell.font = new_font

It seems like earlier versions (1.9 to 2.4?) had a copy method on the font that is now deprecated and raises a warning:

cell.font = cell.font.copy(strike=True)

Versions up to 1.8 had mutable fonts, so you could just do this:

cell.font.strike=True

That now raises an error.

New 2021 Updated Way of Changing FONT in OpenPyXl:

sheet.cell.font = Font(size=23, underline='single', color='FFBB00', bold=True, italic=True)

Full Code:

import openpyxl  # Connect the library
from openpyxl import Workbook
from openpyxl.styles import PatternFill  # Connect cell styles
from openpyxl.workbook import Workbook
from openpyxl.styles import Font, Fill  # Connect styles for text
from openpyxl.styles import colors  # Connect colors for text and cells

wb = openpyxl.Workbook()  # Create book
work_sheet = wb.create_sheet(title='Testsheet')  # Created a sheet with a name and made it active

work_sheet['A1'] = 'Test text'
work_sheet_a1 = work_sheet['A5']  # Created a variable that contains cell A1 with the existing text
work_sheet_a1.font = Font(size=23, underline='single', color='FFBB00', bold=True,
                          italic=True)  # We apply the following parameters to the text: size - 23, underline, color = FFBB00 (text color is specified in RGB), bold, oblique. If we do not need a bold font, we use the construction: bold = False. We act similarly if we do not need an oblique font: italic = False.

# Important:
# if necessary, the possibility of using standard colors is included in the styles, but the code in this case will look different:
work_sheet_a1.font = Font(size=23, underline='single', color=colors.RED, bold=True,
                              italic=True)  # what color = colors.RED — color prescribed in styles
work_sheet_a1.fill = PatternFill(fill_type='solid', start_color='ff8327',
                                 end_color='ff8327')  # This code allows you to do design color cells

You can define a common style then you can apply the same to any cell or range.

Define Style:

Apply on a cell.

This worked for me (font colour + bold font):

from openpyxl.styles import colors
from openpyxl.styles import Font, Color
from openpyxl import Workbook

wb = Workbook()
ws = wb['SheetName']

ws.cell(row_number,column_number).font = Font(color = "0000FF",bold = True)