function convertToBTCFromSatoshi($value){
    $BTC = ($value / 100000000 );
    return (float)$BTC;
}

php > echo 10000.00000001 * 2;
20000.00000002
php > echo 100000.00000001 * 2;
200000.00000002
php > echo 1000000.00000001 * 2;
2000000

/** Convert Satoshis to a string that can be displayed to users.
 *  input: $value Integer or string that can be parsed as an int.
 *  output: string (eg: "1.00400000")
 */
function convertToBTCFromSatoshi($value){
    return bcdiv( intval($value), 100000000, 8 );
}

rtrim($value, "0"); // trim zeros from the right-hand side

function convertToBTCFromSatoshi($value) {
    $BTC = $value / 100000000 ;
    return $BTC;
}
function formatBTC($value) {
    $value = sprintf('%.8f', $value);
    $value = rtrim($value, '0') . ' BTC';
    return $value;
}
echo formatBTC(convertToBTCFromSatoshi(5000));

0.00005 BTC