Converte tamanho em Kb, Mb, Gb, Tb, etc

ByteSize.php

<?php
class ByteSize
{
    const KB = 1;
    const MB = 2;
    const GB = 3;
    const TB = 4;
    const PB = 5;
    const EB = 6;
    const ZB = 7;
    const YB = 8;

    private $acronyms = array(
        'Kb', 'Mb', 'Gb', 'Tb', 'Pb', 'Eb', 'Zb', 'Yb'
    );

    private $precision = 2;

    /**
     * Set size
     *
     * @param int $size
     * @return void
     */
    public function setSize($size)
    {
        $this->size = $size;
    }

    /**
     * Set precision
     *
     * @param int $precision
     * @return void
     */
    public function setPrecision($precision)
    {
        $this->precision = $precision;
    }

    /**
     * Change size acronyms
     *
     * @param int    $type
     * @param string $acronym
     * @throws \Inphinit\Experimental\Exception
     * @return void
     */
    public function setUnit($type, $acronym)
    {
        if (array_key_exists($type - 1, $this->acronyms) === false) {
            throw new Exception('Invalid format', 2);
        }

        $this->acronyms[$type - 1] = $acronym;
    }

    /**
     * Return size by defined format
     *
     * @param int $type
     * @throws \Inphinit\Experimental\Exception
     * @return string
     */
    public function format($type)
    {
        if (array_key_exists($type - 1, $this->acronyms) === false) {
            throw new Exception('Invalid format', 2);
        }

        if ($this->size > 0) {
            $size = $this->size / pow(1024, $type);
        } else {
            $size = 0;
        }

        return sprintf('%.' . $this->precision . 'f', $size) . $this->acronyms[$type - 1];
    }

    /**
     * Return size and detect format
     *
     * @return string
     */
    public function auto()
    {
        $type = intval(log($this->size) / log(1024));

        if ($type < 1) {
            $type = 1;
        }

        return $this->format($type);
    }
}

$x = new ByteSize;
$x->setSize(1024 * 1024*1024);
$x->setPrecision(2);

echo $x->auto(), PHP_EOL,
     $x->format(ByteSize::KB), PHP_EOL,
     $x->format(ByteSize::MB), PHP_EOL,
     $x->format(ByteSize::GB), PHP_EOL,
     $x->format(ByteSize::TB), PHP_EOL,
     $x->format(ByteSize::PB), PHP_EOL,
     $x->format(ByteSize::EB), PHP_EOL,
     $x->format(ByteSize::ZB), PHP_EOL,
     $x->format(ByteSize::YB), PHP_EOL;