In this post I am going to explain how to resize product image in Magento 2.

Using the below code snippet you can resize the product image in the template (.phtml) file.

<?php

$productId = '12';
$_product = $block->getProductById($productId);

$imageHelper = $this->helper('Magento\Catalog\Helper\Image');

$imgWidth = 350;
$imgHeight = 400;
$imageId = 'category_page_grid';

$productImage = $imageHelper->init($_product, $imageId)
				->constrainOnly(TRUE)
				->keepAspectRatio(TRUE)
				->keepTransparency(TRUE)
				->keepFrame(TRUE)
				->resize($imgWidth, $imgHeight);

$productImageUrl = $productImage->getUrl();

?>
<img class="product-image-photo" src="<?php echo $productImageUrl; ?>" alt="<?php echo $_product->getTitle();?>" />

Thats it. Enjoy Magento 2!!