Return total number of items in Cart in Magento 1

total-number-of-items.php

<?php
$_cartQty = $this->helper('checkout/cart')->getItemsCount(); // Shows the different kind of items in cart (NOT TOTAL!)

$_cartQty = $this->helper('checkout/cart')->getSummaryCount(); // Shows the total amount of items in cart

$_cartQty = Mage::getModel('checkout/cart')->getQuote()->getItemsQty(); // Alternative method

$_cartQty = round(Mage::getModel('checkout/cart')->getQuote()->getItemsQty(), 0); // You can strip the decimals (everything after the dot) by wrapping it in a round-function

// To increase readability you could also do the following:
$_cartQty = Mage::getModel('checkout/cart')->getQuote()->getItemsQty();
$_cartQty = round($_cartQty, 0);