Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Shared/Font.php
public static function getTextWidthPixelsApprox($columnText, \PhpOffice\PhpSpreadsheet\Style\Font $font, $rotation = 0)
    {
        $fontName = $font->getName();
        $fontSize = $font->getSize();

        // Calculate column width in pixels. We assume fixed glyph width. Result varies with font name and size.
        switch ($fontName) {
            case 'Calibri':
                // value 8.26 was found via interpolation by inspecting real Excel files with Calibri 11 font.
                $columnWidth = (int) (8.26 * StringHelper::countCharacters($columnText));
                $columnWidth = $columnWidth * $fontSize / 11; // extrapolate from font size
                break;
            case 'Arial':
                // value 8 was set because of experience in different exports at Arial 10 font.
                $columnWidth = (int) (8 * StringHelper::countCharacters($columnText));
                $columnWidth = $columnWidth * $fontSize / 10; // extrapolate from font size
                break;
            case 'Verdana':
                // value 8 was found via interpolation by inspecting real Excel files with Verdana 10 font.
                $columnWidth = (int) (8 * StringHelper::countCharacters($columnText));
                $columnWidth = $columnWidth * $fontSize / 10; // extrapolate from font size
                break;
            default:
                // just assume Calibri
                $columnWidth = (int) (8.26 * StringHelper::countCharacters($columnText));
                $columnWidth = $columnWidth * $fontSize / 11; // extrapolate from font size
                break;
        }

        // Calculate approximate rotated column width
        if ($rotation !== 0) {
            if ($rotation == -165) {
                // stacked text
                $columnWidth = 4; // approximation
            } else {
                // rotated text
                $columnWidth = $columnWidth * cos(deg2rad($rotation))
                                + $fontSize * abs(sin(deg2rad($rotation))) / 5; // approximation
            }
        }

        // pixel width is an integer
        return (int) $columnWidth;
    }
public static function getTextWidthPixelsApprox($columnText, \PhpOffice\PhpSpreadsheet\Style\Font $font, $rotation = 0)
    {
        $fontName = $font->getName();
        $fontSize = $font->getSize();

        // Calculate column width in pixels. We assume fixed glyph width. Result varies with font name and size.
        switch ($fontName) {
            case 'Calibri':
                // value 8.26 was found via interpolation by inspecting real Excel files with Calibri 11 font.
                $columnWidth = (int) (8.26 * StringHelper::countCharacters($columnText));
                $columnWidth = $columnWidth * $fontSize / 11; // extrapolate from font size
                break;
            case 'Arial':
                // value 8 was set because of experience in different exports at Arial 10 font.
                $columnWidth = (int) (8 * StringHelper::countCharacters($columnText));
                $columnWidth = $columnWidth * $fontSize / 10; // extrapolate from font size
                break;
            case 'Verdana':
                // value 8 was found via interpolation by inspecting real Excel files with Verdana 10 font.
                $columnWidth = (int) (8 * StringHelper::countCharacters($columnText));
                $columnWidth = $columnWidth * $fontSize / 10; // extrapolate from font size
                break;
            default:
                // just assume Calibri
                $columnWidth = (int) (8.26 * StringHelper::countCharacters($columnText));
                $columnWidth = $columnWidth * $fontSize / 11; // extrapolate from font size
                break;
        }

        // Calculate approximate rotated column width
        if ($rotation !== 0) {
            if ($rotation == -165) {
                // stacked text
                $columnWidth = 4; // approximation
            } else {
                // rotated text
                $columnWidth = $columnWidth * cos(deg2rad($rotation))
                                + $fontSize * abs(sin(deg2rad($rotation))) / 5; // approximation
            }
        }

        // pixel width is an integer
        return (int) $columnWidth;
    }
Get approximate width in pixels for a string of text in a certain font at a certain rotation angle.

@param string $columnText
@param \PhpOffice\PhpSpreadsheet\Style\Font $font
@param int $rotation

@return int Text width in pixels (no padding added)