Estimate glyph widths for sans serif 16px font

glyph-width.php

<?php

function get_text_width(string $text): int
{
    $glyph_widths = [
        'A' => 10.67,
        'B' => 10.67,
        'C' => 11.55,
        'D' => 11.55,
        'E' => 10.67,
        'F' => 9.77,
        'G' => 12.45,
        'H' => 11.55,
        'I' => 4.45,
        'J' => 8.00,
        'K' => 10.67,
        'L' => 8.90,
        'M' => 13.33,
        'N' => 11.55,
        'O' => 12.45,
        'P' => 10.67,
        'Q' => 12.45,
        'R' => 11.55,
        'S' => 10.67,
        'T' => 9.77,
        'U' => 11.55,
        'V' => 10.67,
        'W' => 15.10,
        'X' => 10.67,
        'Y' => 10.67,
        'Z' => 9.77,
        'a' => 7.10,
        'b' => 8.00,
        'c' => 7.10,
        'd' => 8.00,
        'e' => 7.10,
        'f' => 5.33,
        'g' => 8.00,
        'h' => 8.00,
        'i' => 4.45,
        'j' => 4.45,
        'k' => 8.00,
        'l' => 4.45,
        'm' => 12.45,
        'n' => 8.00,
        'o' => 8.00,
        'p' => 8.00,
        'q' => 8.00,
        'r' => 5.33,
        's' => 6.23,
        't' => 4.45,
        'u' => 8.00,
        'v' => 8.00,
        'w' => 11.55,
        'x' => 8.00,
        'y' => 8.00,
        'z' => 7.10,
    ];
    
    $letters = preg_replace('/[^a-zA-Z]/', 'b', iconv('UTF-8', 'ASCII//TRANSLIT//IGNORE', $text));

    return (int) array_reduce(str_split($letters), static function ($width, $char) use ($glyph_widths) {
        return $width + $glyph_widths[$char];
    }, 0);
}