How do I disable form resizing for users?

How do I disable form resizing for users? Which property is used?

I tried AutoSize and AutoSizeMode.

Change the FormBorderStyle to one of the fixed values: FixedSingle, Fixed3D, FixedDialog or FixedToolWindow.

The FormBorderStyle property is under the Appearance category.

Or check this:

// Define the border style of the form to a dialog box.
form1.FormBorderStyle = FormBorderStyle.FixedDialog;

// Set the MaximizeBox to false to remove the maximize box.
form1.MaximizeBox = false;

// Set the MinimizeBox to false to remove the minimize box.
form1.MinimizeBox = false;

// Set the start position of the form to the center of the screen.
form1.StartPosition = FormStartPosition.CenterScreen;

// Display the form as a modal dialog box.
form1.ShowDialog();

Use the FormBorderStyle property. Make it FixedSingle:

this.FormBorderStyle = FormBorderStyle.FixedSingle;

Use the FormBorderStyle property of your Form:

this.FormBorderStyle = FormBorderStyle.FixedDialog;

Change this property and try this at design time:

FormBorderStyle = FormBorderStyle.FixedDialog;

Designer view before the change:

I always use this:

// Lock form
this.MaximumSize = this.Size;
this.MinimumSize = this.Size;

This way you can always resize the form from Designer without changing code.

Using the MaximumSize and MinimumSize properties of the form will fix the form size, and prevent the user from resizing the form, while keeping the form default FormBorderStyle.

this.MaximumSize = new Size(XX, YY);
this.MinimumSize = new Size(X, Y);

I would set the maximum size, minimum size and remove the gripper icon of the window.

Set properties (MaximumSize, MinimumSize, and SizeGripStyle):

this.MaximumSize = new System.Drawing.Size(500, 550);
this.MinimumSize = new System.Drawing.Size(500, 550);
this.SizeGripStyle = System.Windows.Forms.SizeGripStyle.Hide;