$(function() { $('#currentConsumed').keyup(function() { var currentConsumed = $(this).val(); if(!parseFloat(currentConsumed)) currentConsumed = 0; var totalConsumed = parseFloat(currentConsumed) + parseFloat(consumed); totalConsumed = Math.round(totalConsumed * 1000) / 1000; $('#totalConsumed').html(totalConsumed); $('#consumed').val(totalConsumed); }) })