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Posted 7 Jan 2004


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Adjust combo box drop down list width to longest string width

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4.73/5 (38 votes)
7 Jan 2004
Automatically adjust the width of the drop down list of a combo box to the width of its longest item string.

Sample Image - ComboBoxAutoWidth.jpg


This small snippet of code will show you how to automatically adjust the size of the drop down list of a combo box to fit the size of the longest string in its items.


Step 1: Add an event handler for the DropDown event of the combo box. Call it AdjustWidthComboBox_DropDown for the sake of the following code.

Step 2: Add the following event handler code.

private void AdjustWidthComboBox_DropDown(object sender, System.EventArgs e)
    ComboBox senderComboBox = (ComboBox)sender;
    int width = senderComboBox.DropDownWidth;
    Graphics g = senderComboBox.CreateGraphics();
    Font font = senderComboBox.Font;
    int vertScrollBarWidth = 

    int newWidth;
    foreach (string s in ((ComboBox)sender).Items)
        newWidth = (int) g.MeasureString(s, font).Width 
            + vertScrollBarWidth;
        if (width < newWidth )
            width = newWidth;
    senderComboBox.DropDownWidth = width;


The code assumes that the handler is only for a ComboBox and does a cast without checking the type of the sender.

It then gets the Graphics and Font objects for the combo box which will help us to measure the size of the string in the list.

senderComboBox.Items.Count>senderComboBox.MaxDropDownItems checks whether a scrollbar will be displayed. If it is going to be displayed, then we get its width to adjust the size of the drop down list accordingly.

We then scroll through the list of items checking the size of each item and finally setting the width of the drop down list to the width of the largest item including scroll bar width.


This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

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Comments and Discussions

QuestionImplementation sample for C++/CLI Pin
Damian Suess13-Nov-18 10:18
MemberDamian Suess13-Nov-18 10:18 
Generalperhaps incomplete code? Pin
black__cat19-Mar-18 14:39
Memberblack__cat19-Mar-18 14:39 
QuestionThank you Pin
aazam rafiee zade25-May-16 4:12
Memberaazam rafiee zade25-May-16 4:12 
QuestionInvalidcastException Pin
Member 1084897527-May-14 22:45
MemberMember 1084897527-May-14 22:45 
QuestionBest Solutions Pin
nkarankal22-Nov-13 19:53
professionalnkarankal22-Nov-13 19:53 
GeneralMy vote of 5 Pin
Mahesh Sanika21-Aug-13 0:45
MemberMahesh Sanika21-Aug-13 0:45 
GeneralThanks Pin
or19717-Jun-12 5:45
Memberor19717-Jun-12 5:45 
GeneralMy vote of 5 Pin
Hesron M. Gozano19-Nov-11 17:36
MemberHesron M. Gozano19-Nov-11 17:36 
Questioncode for webbased application Pin
Atul Naik16-Nov-11 19:05
MemberAtul Naik16-Nov-11 19:05 
Questioncode for webbased application Pin
Atul Naik16-Nov-11 19:03
MemberAtul Naik16-Nov-11 19:03 
GeneralSolution for databound combobox inside Pin
avalon1237-Apr-11 21:29
Memberavalon1237-Apr-11 21:29 
GeneralMaking it work with Databound combobox Pin
kanreddyjp11-Oct-10 0:38
Memberkanreddyjp11-Oct-10 0:38 
GeneralVERY Useful Pin
Omar Gameel Salem16-Apr-10 8:30
professionalOmar Gameel Salem16-Apr-10 8:30 
GeneralUsing extension method Pin
C#rizje31-May-09 5:05
MemberC#rizje31-May-09 5:05 
QuestionCode Pin
DanielHH28-Apr-09 7:01
MemberDanielHH28-Apr-09 7:01 
QuestionOn which event we have to bind? Pin
harshkapoors19-Apr-09 4:11
Memberharshkapoors19-Apr-09 4:11 
GeneralPlz provide sorce code for this article.. Pin
Member 325917710-Jan-09 2:38
MemberMember 325917710-Jan-09 2:38 
GeneralSuggestion: Don't assign DropDownWidth to variable 'width' Pin
qian_xu31-Oct-07 16:54
Memberqian_xu31-Oct-07 16:54 
GeneralCouple of suggestions Pin
Marcus J. Smith30-Mar-07 10:01
professionalMarcus J. Smith30-Mar-07 10:01 
GeneralDropDown list width increment according to the value in list Pin
vinodgn4-Nov-06 18:28
Membervinodgn4-Nov-06 18:28 
GeneralRe: DropDown list width increment according to the value in list Pin
Marcus J. Smith30-Mar-07 9:59
professionalMarcus J. Smith30-Mar-07 9:59 
GeneralProblem with foreign language (non-English) Pin
AesopTurtle10-Nov-05 22:22
MemberAesopTurtle10-Nov-05 22:22 
GeneralDropDownList Pin
DoomKickYourAss11-Aug-05 5:26
MemberDoomKickYourAss11-Aug-05 5:26 
GeneralVB.Net Code Pin
alardaen21-May-05 2:50
Memberalardaen21-May-05 2:50 
Generalcustom Validator in asp .net Pin
Member 158550213-Dec-04 0:45
MemberMember 158550213-Dec-04 0:45 

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