Display WooCommerce discount as a percentage

woocommerce-discount-percentage.php

<?php
function themeslug_discount_product($price, $product){
	global $product;
	$discount = $product->sale_price ;
	if ($discount) {
		$percentage = round( ( ( $product->regular_price - $product->sale_price ) / $product->regular_price ) * 100 );
		$wc_percent  = $price .' <span class="product-discount">'. sprintf( __('%s', 'themeslug' ), $percentage . '% OFF</span>' );		
	}
	else{
		$wc_percent  = $price .' <span class="no_discount">'. sprintf( __('0%s', 'themeslug' ), $percentage . '% OFF</span>' );
	}
	return $wc_percent;	
	}

add_filter( 'woocommerce_sale_price_html', 'themeslug_discount_product', 10, 2 ); ?>