how to find range inside checkbox

I have a column named weight in my table accounts. i need to fetch the values from this column like,

when the user clicks weight from 40 - 100, It need to display all the persons with weight in between 40 and 100.

This is my html code,

<div class="float-right span35">
    <form class="list-wrapper search-form" method="get" action="/index.php">
        <div class="list-header">
            Talent Search
        </div>
                <h4 style="margin-left: 10px; color: gray;">Weight</h4>
                <fieldset id="weight">
                    <input type="checkbox" name="weight" value="1" />Below 40<br>
                    <input type="checkbox" name="weight" value="2" />40-70<br>
                    <input type="checkbox" name="weight" value="3" />70-100<br>
                    <input type="checkbox" name="weight" value="4" />Above 100<br>
                </fieldset>
                <br/>
                <input style="margin-left: 10px" type="submit" name="submit" value="search"/><br><br>
                <input type="hidden" name="tab1" value="search">
        </form>
</div>

This is my php code,

if(isset($_GET['submit'])){


    $weight = ($_GET['weight'])? $escapeObj->stringEscape($_GET['weight']): NULL;

    $sql = "SELECT id FROM `".DB_ACCOUNTS."` WHERE `id` IS NOT NULL ";

    if(is_numeric($weight) && $weight != NULL){
        $sql .= "AND `weight` IN (".$weight.")"; 
        $is_weight = true;
    }

    $sql .= " ORDER BY `id` ASC";

    }
    if($is_weight){
        $themeData['weight_'.$weight] = 'checked';
    }

    $query = $conn->query($sql);
    if($query->num_rows > 0){
            while($fetch = $query->fetch_array(MYSQLI_ASSOC)){
                $get[] = $fetch['id'];
            }

            $i = 0;
            $listResults = '';

            $themeData['page_title'] = "Advanced Search - ".$lang['search_result_header_label']; 
            foreach($get as $row){
                $timelineObj = new \SocialKit\User();
                $timelineObj->setId($row);
                $timeline = $timelineObj->getRows();

                $themeData['list_search_id'] = $timeline['id'];
                $themeData['list_search_url']   = $timeline['url'];
                $themeData['list_search_username'] = $timeline['username'];
                $themeData['list_search_name'] = $timeline['name'];
                $themeData['list_search_thumbnail_url'] = $timeline['thumbnail_url'];

                $themeData['list_search_button'] = $timelineObj->getFollowButton();

                $listResults .= \SocialKit\UI::view('search/list-each');
                $i++;
            }
            $themeData['list_search_results'] = $listResults; 

    }

}

This code is almost working for an single weight from table. But I need to create a range in between the checkbox values as i mentioned in the code. Do i need to update the code.