Image Resizer

Government exam portals, visa applications, and e-commerce dashboards rarely ask for "a smaller photo" - they demand an exact specification such as 3.5 cm × 4.5 cm at 300 DPI under 50 KB, or 1200 × 630 px WebP. Use this batch image resizer in your browser to scale and crop JPG, PNG, and WebP photos by Pixels (px), Percentage (%), Physical Print Units (Inches, cm, mm at custom DPI), or an exact Target File Size in Kilobytes (KB) with zero server uploads.

When exact pixel dimensions, physical print units, and KB caps collide

Three different worlds ask you to resize images in three completely different ways:

1. Government, UPSC/SSC exam, and Visa portals (Target KB + Physical cm/mm): Official application forms routinely specify both physical dimensions (such as a 3.5 cm × 4.5 cm passport photo or 4 cm × 2 cm signature scan at 300 DPI) and a strict file size window (such as between 20 KB and 50 KB). Most basic resizers only let you type pixel width and leave you guessing what quality slider setting will land at 46 KB.
2. Web & Social Media headers (Exact Pixels + Aspect Ratio Crop): OpenGraph social cards require 1200 × 630 px, YouTube thumbnails need 1280 × 720 px (16:9), and Shopify product cards want 2048 × 2048 px (1:1). If you simply stretch a 4:3 photo into a 1:1 square without cropping or padding first, the subject looks squashed.
3. Bulk Camera Folder Downscaling (Percentage Scale): When you copy 40 DSLR or iPhone photos at 4032 × 3024 px to email to a client or embed in a report, scaling the whole batch to 50% or 25% shrinks total folder weight by 85%+ in two clicks.

How to use the batch image resizer step by step

Method 1: Resize by Exact Pixels or Percentage (By Dimensions / By Percentage Tab)

1. Load your image batch: Drag one or dozens of JPG, PNG, or WebP files into the upload zone (or press Ctrl + V to paste from your clipboard).
2. Enter target width & height or scale percentage: In By Dimensions (px) mode, type your exact pixel dimensions (keeping the Lock Aspect Ratio chain icon active to avoid stretching), or switch to By Percentage (25%, 50%, 75%) to downscale a whole camera folder proportionally.
3. Crop or rotate individual frames: Click Crop & Rotate on any card that needs framing adjustments (1:1, 16:9, 4:3, 3:2, or freeform), pick your output format, click Apply to All Images, and export as a ZIP archive.

Method 2: Resize by Physical Print Units (cm, mm, in at Custom DPI)

1. Switch the dimension unit dropdown: Inside the By Dimensions tab, change the unit selector from px to Centimeters (cm), Millimeters (mm), or Inches (in).
2. Set your target print resolution (DPI): Enter your required dots-per-inch (standard passport, visa, and commercial print forms specify 300 DPI) alongside the physical width and height (e.g., 3.5 cm × 4.5 cm).
3. Export the exact calculated pixel grid: The engine converts physical measurements into the exact pixel matrix (3.5 cm @ 300 DPI = 413 px) and renders your print-ready file.

Method 3: Compress & Resize to a Strict Kilobyte Limit (By Target File Size KB Tab)

1. Select Target KB mode: Switch to the Target File Size (KB) tab when an exam, visa, or government portal rejects uploads above a fixed ceiling (such as 20 KB–50 KB or 100 KB).
2. Enter your maximum KB cap: Type your exact ceiling (e.g., 48 KB) and choose JPEG or WebP output.
3. Download the binary-searched output: The solver automatically binary-searches encoder quantization levels (and sub-scales only if mathematically required) so every exported file lands cleanly below your kilobyte cap.

Binary-search Target KB solver, physical DPI converter, and interactive cropper

This workspace solves the math behind print resolution and byte budgets automatically so you never have to re-export a photo six times by trial and error.

• Exact Target KB auto-solver: Need a JPEG or WebP strictly under 50 KB or 100 KB? Enter your target kilobyte ceiling in Target KB mode, and the engine runs an iterative binary search across encoder quantization levels (and controlled sub-scaling if needed) to land right underneath your target byte limit.
• Physical Print Units (in, cm, mm) with live DPI math: Switch the unit selector from px to cm, mm, or in and set your print resolution (default 300 DPI). Typing 3.5 cm × 4.5 cm at 300 DPI automatically calculates the exact pixel matrix ($rac{3.5}{2.54} \times 300 = 413 \times 531\text{ px}$).
• Interactive Crop, Rotate & Flip Studio: Click any image in the batch to crop with rule-of-thirds guides, lock aspect ratios (1:1, 4:5, 16:9, 4:3), rotate 90° left/right, or flip horizontally/vertically.
• One-click Batch synchronization: Configure dimensions, format, and quality on one image and click Apply to All N Images to process an entire product catalog uniformly.

Worked example: preparing a 3.5×4.5 cm visa photo under 50 KB

Suppose you take a portrait against a wall with your smartphone (Portrait-Original.jpg, 3024 × 4032 pixels, 4.15 MB). The consulate portal requires:

• Dimensions: 3.5 cm wide × 4.5 cm high at 300 DPI
• Format: JPEG
• Maximum file size: Under 50 KB

Inside the workspace:

1. You load Portrait-Original.jpg and crop the head-and-shoulders frame to a 7:9 (3.5:4.5) portrait ratio.
2. In the Dimensions tab, you switch units to Centimeters (cm), set DPI = 300, and type Width = 3.5, Height = 4.5. The pixel readout confirms 413 × 531 px.
3. You switch to Target KB (or set Output Format to JPEG with Target = 45 KB). The binary-search encoder tests JPEG quality levels in memory and locks in at Quality 84%, producing a crisp 413 × 531 px JPEG weighing exactly 43.8 KB - down from 4.15 MB and ready for immediate portal upload.

Avoiding upscaling blur and choosing the right output format

Keep two golden rules of digital imaging in mind when resizing:

• Downscaling vs. Upscaling: Shrinking a 4000 × 3000 px photo down to 1200 × 900 px looks razor-sharp because the high-quality bicubic/Lanczos canvas sampler averages multiple source pixels into each output pixel. Stretching a tiny 300 × 200 px thumbnail up to 1920 × 1080 px cannot invent missing optical detail; the image will look soft.
• Target KB mode requires a lossy format (JPEG or WebP): If you need to hit a strict kilobyte ceiling like 50 KB or 100 KB, always set the Output Format dropdown to JPEG or WebP rather than PNG. Because PNG is lossless, it cannot dial down quantization to fit a strict kilobyte budget without shrinking the pixel dimensions dramatically.

100% local browser execution

Passport photos, signature scans, and client product batches stay 100% inside your browser's local RAM. No images are ever uploaded to a remote server.

Related image and document tools

Need to make the background of your portrait pure white before resizing it for a passport or visa? Start in the AI Background Remover. You can also convert across 9 formats in the Image Converter, combine resized scans into a document with Image to PDF, strip GPS metadata in the EXIF Privacy Scrubber, or read our guide on how to resize images in bulk for free.