How to add custom attribute to Magento’s registeration page

For demonstration, we will add a height attribute to Magento’s registeration page
1. Add following lines from 7 to 10 in app\code\core\Mage\Customer\etc\config.xml

<customer_account>
...
 <gender>
  <create>1</create>
  <update>1</update>
 </gender>
 <height>
  <create>1</create>
  <update>1</update>
 </height>
...
</customer_account>

2. In app\design\frontend\default\yourtheme\customer\form\edit.phtml, find the below code

<li>
	<label for="email" class="required"><em>*</em><?php echo $this->__('Email Address') ?></label>
	<div class="input-box">
		<input type="text" name="email" id="email" value="<?php echo $this->htmlEscape($this->getCustomer()->getEmail()) ?>" title="<?php echo $this->__('Email Address') ?>" class="input-text required-entry validate-email" />
	</div>
</li>

and then add this code snippet right after the above code

<li>
	<div class="input-box">
		<label for="height"><?php echo $this->__('Height') ?> </label><br/>
		<input type="text" name="height" id="height" value="<?php echo $this->htmlEscape($this->getCustomer()->getHeight()) ?>" title="<?php echo $this->__('Height') ?>" class="input-text" />
	</div>
</li>

4. Add this code at the beginning in the file app\design\frontend\default\yourtheme\template\persistent\customer\form\register.phtml

<?php
$setup = Mage::getModel('customer/entity_setup', 'core_setup');
$setup->addAttribute('customer', 'height', array(
    'type'			=> 'decimal',
    'label'         => 'Height',
	'input'         => 'text',
    'required'      => false,
    'sort_order'    => 8,
));
if (version_compare(Mage::getVersion(), '1.6.0', '<='))
{
      $customer = Mage::getModel('customer/customer');
      $attrSetId = $customer->getResource()->getEntityType()->getDefaultAttributeSetId();
      $setup->addAttributeToSet('customer', $attrSetId, 'General', 'height');
}
if (version_compare(Mage::getVersion(), '1.4.2', '>='))
{
    Mage::getSingleton('eav/config')
    ->getAttribute('customer', 'height')
    ->setData('used_in_forms', array('adminhtml_customer','customer_account_create','customer_account_edit','checkout_register'))
    ->save();
}
?>

Find the below code

<li>
 <label for="email_address" class="required"><em>*</em><?php echo $this->__('Email Address') ?></label>
 <div class="input-box">
  <input type="text" name="email" id="email_address" value="<?php echo $this->escapeHtml($this->getFormData()->getEmail()) ?>" title="<?php echo $this->__('Email Address') ?>" class="input-text validate-email required-entry" />
 </div>
</li>

and then add this code snippet right after the above code

					<div class="input-box">
					<label for="height"><?php echo $this->__('Height') ?></label><br/>
					<input type="text" name="height" id="height" value="<?php echo $this->htmlEscape($this->getFormData()->getHeight()) ?>" title="<?php echo $this->__('Height') ?>" class="input-text" />
					</div>

6. Reload the registration page, you will see the Height attribute showing up.

7. If you go to the Magento database, and run this query:

select * from eav_attribute 
where attribute_code="height";

you should see the newly added attribute “height”.

Note: The above are demonstrations for the steps needed to add a new attribute in Magento, which involved changing the Magento core files. The proper way to do it is to create a new module which won’t change Magento’s core files and does the necessary steps mentioned above for adding new attributes in Magento.