clase para utm.txt

function utm_to_latlng($easting, $northing, $zone) {

    // Calculate the false easting and false northing for the zone.
    $falseEasting = 500000 + (6 * ($zone - 1));
    $falseNorthing = 10000000 + (zone * 100000);

    // Calculate the central meridian for the zone.
    $centralMeridian = (6 * $zone) - 180;

    // Calculate the scale factor for the zone.
    $scaleFactor = 0.9996;

    // Calculate the latitude and longitude values.
    $latitude = (atan2(($northing - $falseNorthing) * $scaleFactor, ($easting - $falseEasting)) * 180 / pi());
    $longitude = ($centralMeridian + atan2(0.0000112 * ($northing - $falseNorthing), $easting - $falseEasting) * 180 / pi());

    // Return the latitude and longitude values.
    return array(
        'latitude' => $latitude,
        'longitude' => $longitude
    );
}

Nicaragua es zona 16

*******************************
<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;

class UTMController extends Controller
{
    public function index()
    {
        return view('utm');
    }

    public function convert(Request $request)
    {
        $easting = $request->input('easting');
        $northing = $request->input('northing');
        $zone = $request->input('zone');

        $latlng = utm_to_latlng($easting, $northing, $zone);

        return view('utm', compact('latlng'));
    }
}


*********************************
<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;

class TestController extends Controller
{
    public function index()
    {
        return view('test');
    }

    public function store(Request $request)
    {
        $easting = $request->input('easting');
        $northing = $request->input('northing');
        $zone = $request->input('zone');

        $latlng = utm_to_latlng($easting, $northing, $zone);

        $test = new Test();
        $test->name = $request->input('name');
        $test->utm_easting = $easting;
        $test->utm_northing = $northing;
        $test->utm_zone = $zone;
        $test->latitude = $latlng['latitude'];
        $test->longitude = $latlng['longitude'];

        $test->save();

        return redirect('test');
    }
}