How to Convert Images Between JPEG, PNG & WebP Online

Why Image Format Matters

Every image format was designed with a specific purpose in mind. Choosing the wrong one can mean bloated page load times, lost transparency, visible compression artifacts, or files that simply will not open on certain devices. Whether you are building a website, preparing images for print, or sharing photos by email, understanding when to use JPEG, PNG, or WebP is a practical skill that saves time and avoids frustration.

This guide covers the key differences between the most common image formats, explains when each one is the right choice, and walks you through how to convert between them using ToolMint's browser-based Image Studio.

Understanding Image Formats

JPEG (Joint Photographic Experts Group)

JPEG has been the standard format for photographs since the early 1990s. It uses lossy compression, which means it discards some image data to achieve smaller file sizes. At high quality settings (80-95%), the difference is nearly invisible to the human eye, but at lower settings, you will start to see blocky artifacts, especially around sharp edges and text.

Best for: Photographs, complex images with gradients, social media posts, email attachments.

Avoid when: You need transparency, your image contains text or sharp lines, or you plan to edit and re-save the file multiple times (each save degrades quality further).

PNG (Portable Network Graphics)

PNG uses lossless compression, which preserves every pixel exactly as it was in the original. This makes it the go-to format for graphics, logos, screenshots, and any image where sharp edges or transparency matter. The trade-off is file size. A PNG version of a photograph can be five to ten times larger than a JPEG of the same image.

Best for: Logos, icons, screenshots, graphics with text, images requiring transparency, digital art with flat colors.

Avoid when: File size is a concern and the image is a photograph. A 4000x3000 photo saved as PNG might be 15 MB, while the JPEG equivalent at 90% quality could be under 2 MB with no visible difference.

WebP

Developed by Google, WebP combines the best qualities of JPEG and PNG into a single format. It supports both lossy and lossless compression, transparency, and even animation. A WebP image is typically 25-35% smaller than a JPEG of equivalent visual quality, and significantly smaller than PNG for photographic content.

Best for: Web images of all types, blog post images, product photos on e-commerce sites, any situation where both quality and file size matter.

Limitations: While all modern browsers support WebP (Chrome, Firefox, Safari, Edge), some older software and image viewers may not open WebP files. If you need to share an image with someone who might be using outdated tools, JPEG remains the safer choice.

AVIF (AV1 Image File Format)

AVIF is the newest major image format, based on the AV1 video codec. It offers even better compression than WebP, with file sizes often 30-50% smaller than JPEG at the same perceived quality. AVIF supports transparency, wide color gamut, and HDR content.

Best for: Web images where maximum compression is desired, high-quality photography on bandwidth-constrained connections.

Limitations: Browser support is still catching up. Chrome and Firefox handle AVIF well, but Safari added support more recently and some image editing software does not yet support it. Encoding AVIF images is also slower than encoding JPEG or WebP.

BMP (Bitmap)

BMP is an uncompressed raster format that preserves every pixel without any compression at all. File sizes are very large. There is rarely a good reason to use BMP in modern workflows, but you may encounter BMP files from legacy systems or older software.

Best for: Legacy system compatibility, specific industrial or medical imaging workflows.

Avoid when: You have any other option. BMP files are unnecessarily large for almost every use case.

JPEG vs PNG vs WebP: Detailed Comparison

How to Convert Images with ToolMint

ToolMint's Image Studio handles image format conversion entirely in your browser. Your files are never uploaded to a server, which means the conversion is instant and your images remain private.

Step-by-Step Guide

1. Open Image Studio
2. Upload your image by dragging it onto the page or clicking the upload area. The tool accepts JPEG, PNG, WebP, AVIF, BMP, and several other formats.
3. Click the Convert tool in the sidebar
4. Select your target format from the dropdown (JPEG, PNG, WebP, AVIF, or BMP)
5. If converting to a lossy format (JPEG, WebP, or AVIF), adjust the quality slider. For most purposes, 85-90% provides an excellent balance between file size and visual quality.
6. Click Apply Format to perform the conversion
7. Click Export to download the converted image

The entire process takes seconds, even for large images, because everything runs locally on your device.

Batch Conversion Tips

If you have multiple images to convert, the most efficient approach is to establish your workflow first:

• Decide on your target format and quality setting before you begin
• Process images one at a time through the Image Studio, keeping the same settings
• Use consistent naming conventions for your output files
• For large batches of photographs going to the web, WebP at 85% quality is a reliable default

Quality vs File Size: Finding the Right Balance

One of the most common questions about image conversion is how much quality to sacrifice for smaller file sizes. Here is a practical guide:

Quality 95-100%: Nearly indistinguishable from the original. Use this for images that will be printed or where detail is critical (medical imaging, professional photography portfolios). File sizes are only slightly smaller than lossless.

Quality 85-90%: The sweet spot for most web use. Compression artifacts are essentially invisible at normal viewing distances. File sizes are 60-80% smaller than the original.

Quality 70-80%: Good for thumbnails, social media posts, and situations where bandwidth matters more than pixel-perfect quality. Artifacts may be visible if you zoom in, but images look fine at their intended display size.

Quality below 60%: Noticeable degradation. Only use this for very small thumbnails or when extreme file size reduction is necessary.

Web Performance: Why Format Choice Matters for Your Website

If you run a website, image format directly affects your Core Web Vitals scores and search engine rankings. Images are typically the heaviest assets on a web page, often accounting for 50-80% of total page weight.

Switching from JPEG to WebP across your site can reduce image payload by 25-35% with no visible quality loss. For a page with 500 KB of JPEG images, that is 125-175 KB saved per page load. Multiply that across thousands of visitors and the bandwidth savings are significant.

Google's PageSpeed Insights specifically flags opportunities to serve images in next-generation formats like WebP and AVIF. Making this change is one of the easiest wins for improving your Largest Contentful Paint (LCP) score.

Recommended Format Strategy for Websites

• Hero images and large photos: WebP with lossy compression at 85% quality
• Logos and icons: SVG when possible, PNG when SVG is not an option
• Thumbnails: WebP at 80% quality
• Screenshots and diagrams: PNG for crisp text, or WebP lossless if file size is a concern

Resolution and DPI Considerations

Converting between formats does not change the pixel dimensions or DPI (dots per inch) of your image. A 3000x2000 pixel JPEG converted to PNG will still be 3000x2000 pixels.

However, be aware of these related considerations:

• DPI metadata is preserved during format conversion but has no effect on screen display. DPI only matters for print. A 300 DPI image and a 72 DPI image with the same pixel dimensions look identical on screen.
• Downscaling before conversion can dramatically reduce file size. If your source image is 4000 pixels wide but you only need 1200 pixels for your website, resize first, then convert. ToolMint's Image Studio lets you resize and convert in a single workflow.
• Avoid upscaling. Converting a 500x500 image to PNG will not make it higher quality. The pixel data is the same regardless of format.

Combine Conversion with Other Edits

The Image Studio lets you chain multiple operations before exporting, so you do not need separate tools for each step:

• Compress to reduce file size further after conversion
• Resize to specific dimensions for your target platform
• Add a watermark for branding before sharing
• Apply filters or color adjustments for visual consistency
• Crop to remove unwanted areas

All edits are non-destructive with 50-step undo/redo, so you can experiment freely without worrying about losing your original.

Need PDF to Image or Image to PDF?

ToolMint also handles conversions between images and documents:

• PDF to Image — extract pages as JPEG or PNG files
• Image to PDF — combine multiple images into a single PDF document

Frequently Asked Questions

Does converting from JPEG to PNG improve image quality? No. Converting a lossy format (JPEG) to a lossless format (PNG) preserves the image exactly as it is, including any compression artifacts from the original JPEG encoding. It does not recover lost detail. The PNG file will actually be larger because PNG uses lossless compression, so it stores all the data including the artifacts.

What is the best format for images with transparency? PNG is the most widely supported format for transparent images. WebP and AVIF also support transparency with smaller file sizes, but if compatibility with older software is a concern, PNG is the safest choice.

Will converting to WebP break my images on older browsers? WebP is supported by all modern browsers including Chrome, Firefox, Safari (version 14+), and Edge. If you need to support Internet Explorer or very old Safari versions, you can serve JPEG as a fallback. Most websites use the HTML <picture> element to provide both WebP and JPEG versions.

How do I convert images without losing quality? Use lossless conversion. Converting between PNG and WebP lossless preserves every pixel. When converting to JPEG, set the quality slider to 95-100% for minimal loss. For truly lossless results, avoid JPEG entirely since it always applies some compression.

Is it safe to convert images online? With ToolMint, yes. The conversion happens entirely in your browser using WebAssembly. Your images are never uploaded to any server, and no copy of your file exists anywhere other than your own device. This makes it safe even for sensitive or confidential images.

Can I convert HEIC/HEIF images from my iPhone? HEIC is the default photo format on modern iPhones. You can convert HEIC images to JPEG, PNG, or WebP using the Image Studio. Upload the HEIC file and select your desired output format.

What quality setting should I use for WebP? For photographs on the web, 80-85% provides an excellent balance. For images where detail is critical, use 90-95%. For thumbnails or images that will be displayed at small sizes, 70-75% is often sufficient.

Does format conversion change the image dimensions? No. Converting between formats only changes how the pixel data is encoded and compressed. The width, height, and pixel content remain the same. To change dimensions, use the resize tool before or after converting.

Try Image Studio now — convert, edit, and export in one place.