input('kg'); $lbs = $request->input('lbs'); $result = null; // Convert one direction based on which field is filled if ($kg && !$lbs) { $lbs = $kg * 2.20462; $result = "{$kg} KG = " . number_format($lbs, 2) . " lbs"; } elseif ($lbs && !$kg) { $kg = $lbs / 2.20462; $result = "{$lbs} lbs = " . number_format($kg, 2) . " KG"; } else { $result = "Please fill only one field!"; } return view('convert', [ 'kg' => $kg, 'lbs' => $lbs, 'result' => $result, ]); } }