When you enter data into a cell in Microsoft Excel, the application doesn't resize the cell automatically. If the text you enter is larger than the width of the cell, it will overlap onto adjacent cells. You must either increase the width of the column yourself or use the AutoFit function to resize the cell to fit the text exactly.
Using the AutoFit Function
To resize the cell to fit the exact width of your text, point to the border separating the column header from the adjacent cell and then double-click the border when the cursor changes. For example, if the cell you want to resize is located under the "A" column, hover the pointer over the line separating "A" from "B" and then double-click the line. You can also resize the cell automatically by selecting "AutoFit Column Width" from the Format drop-down menu on the Home tab.
Manually Resize the Cell
If you want to increase the amount of white space surrounding your cell, first resize the cell using AutoFit and then select "Column Width" from the Format drop-down menu. Type your desired pixel width in the field and then click "OK." To resize the cell without using precise measurements, follow the instructions in the section above to AutoFit the cell using the mouse, but don't double-click the border. Instead, click and drag the border to the right to increase the column width.