Resize Images in Bulk (Free): Windows, Mac, iPhone, and Online (Exact Dimensions, Quality, and File‑Size Targets)

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By Abdulbatin Anaza • Last updated: May 2026 • Estimated reading time: 14–20 minutes

Need a folder of photos at 1200px wide, product shots under 200 KB, or blog images in WebP? You can Resize Images in Bulk—free—on Windows and Mac, or use safe web tools on any device.

This guide shows how to Resize Images in Bulk using built‑in apps and trusted tools, hit exact pixel dimensions or file‑size targets without ugly artifacts, and set color/metadata so results look consistent everywhere.

Related how‑tos:

Cleaning backgrounds first? Remove Image Background (Free)
Converting iPhone HEICs before resizing? Convert HEIC to JPG or PNG
Rename results neatly in one pass: Rename Files in Bulk (Windows & Mac)
Packaging images into a single doc? Convert Images to PDF (Free)

Pick the right format and size (quick wins)

Use these quick wins to Resize Images in Bulk with consistent, sharp results:

Format: Photos → JPG or WebP (smaller). Graphics/text/transparency → PNG (or WebP lossless). If supported, convert to WebP to save space with similar quality.
Common widths: Blog/portfolio: 1200–1600px; Full‑bleed hero: 1920px; Thumbnails: 320–600px.
Quality: JPG/WebP quality ~75–85% keeps things crisp and small. Reduce dimensions first; then nudge quality for image compression.
Color: Export in sRGB for web consistency. Strip metadata to shrink files (unless you need EXIF).

Myth: “DPI” doesn’t affect web display—pixel dimensions do. DPI only matters for printing.

Method 1: Windows — PowerToys Image Resizer (batch), Photos, Paint, IrfanView

On Windows, these free tools make it easy to Resize Images in Bulk without paying for anything.

A) PowerToys Image Resizer (best batch, free by Microsoft)

Install Microsoft PowerToys (free): learn.microsoft.com/windows/powertoys
Select images in File Explorer → right‑click → Resize pictures.
Pick a preset (Small/Medium/Large) or click Custom (e.g., Width: 1600 px). Check Only shrink to avoid upscaling.
Optional: choose file type (JPG/PNG/WebP) and quality, preserve or strip metadata, and whether to ignore orientation.
Click Resize. Resized copies save next to originals (or choose “Resize the original” if you’re sure).

Tip: PowerToys Image Resizer is a free batch image resizer by Microsoft that lets you Resize Images in Bulk from the right‑click menu.

B) Photos app (quick one‑offs)

Open image in Photos → … menu → Resize → pick a suggested size or Define custom dimensions.

C) Paint (fast resize + save)

Open image in Paint → Resize → set by Pixels (keep Maintain aspect ratio) → OK → Save As JPG/PNG.

D) IrfanView (power batch, free)

Install IrfanView (add plugins if asked): irfanview.com
File → Batch Conversion/Rename → Output format = JPG/WebP/PNG → Advanced → check RESIZE and set width/height, preserve aspect ratio, Don’t enlarge smaller images.
Set quality (JPG/WebP) → choose output folder → Start.

Best for: precise control when you need to Resize Images in Bulk and convert formats at once.

Method 2: Mac — Preview (batch), Finder Quick Action, Automator, Terminal

On macOS, Preview, Quick Actions, and Automator let you Resize Images in Bulk quickly—no extra apps required.

A) Preview (precise batch)

Select images in Finder → right‑click → Open With → Preview.
In Preview’s sidebar press Cmd + A to select all thumbnails.
Tools → Adjust Size… → set width/height (e.g., 1600 px), ensure Scale proportionally and Resample image are on → OK.
File → Export Selected Images… (macOS Sonoma) or export individually: choose Format (JPEG/PNG/WebP if available) and set quality.

Preview can Resize Images in Bulk across many files while preserving aspect ratio and sRGB.

B) Finder Quick Action: Convert Image (Monterey+)

Select images → right‑click → Quick Actions → Convert Image.
Pick Format (JPEG/PNG/HEIF) and Size (Small/Medium/Large/Custom) → toggle Preserve metadata as needed → Convert.

C) Automator one‑click resizer (reusable)

Open Automator → New → Quick Action.
Workflow receives image files in Finder.
Add action Scale Images → set (e.g., 1600 px). Automator offers to add “Copy Finder Items” for safety—accept it.
Save as “Resize to 1600px” → use via right‑click → Quick Actions.

Create reusable Quick Actions to Resize Images in Bulk with a single right‑click.

D) Terminal (sips) — fast and built‑in

# Resize to max dimension 1600px (keeps aspect), write copies to /out
mkdir out
for f in *.jpg *.jpeg *.png; do
  sips -Z 1600 "$f" --out "out/$f"
done

# Convert to JPEG at quality 0.8 while resizing
sips -Z 1600 -s format jpeg -s formatOptions 80 input.png --out output.jpg

With sips, you can script and Resize Images in Bulk in any folder.

Method 3: Online tools (fast—avoid sensitive images)

Use web tools for convenience and to Resize Images in Bulk when you’re away from your main computer—just avoid private or client photos.

Squoosh (by Google): squoosh.app
Open site → drop an image → toggle Resize (set width/height) → choose JPEG/WebP/PNG → set quality → download. Runs mostly client‑side.
BulkResizePhotos (client‑side, many at once): bulkresizephotos.com
Choose mode (Longest Side, Exact Size, Percentage), set size, pick format/quality → Start Resizing. It can Resize Images in Bulk entirely in your browser.
iLoveIMG — Resize: iloveimg.com/resize-image
TinyPNG/TinyJPG (compress + optional resize): tinypng.com

Privacy tips:

Don’t upload confidential/client photos.
Delete uploads after processing if the site stores them.
Prefer offline tools to Resize Images in Bulk for anything sensitive.

Hit a file‑size target (e.g., under 200 KB)

To stay under a size cap, first Resize Images in Bulk to the right dimensions, then fine‑tune quality to reduce file size without banding.

Resize first (e.g., max width 1200–1600 px).
Then set quality (JPG/WebP ~75–85%). Watch for banding in skies/gradients—nudge to 88–90% if needed.
Prefer WebP for smaller files at similar quality (if your platform supports it).
Strip metadata to save a few KB (Squoosh “Remove metadata,” IrfanView options, PowerToys toggle).

CLI power (ImageMagick) — batch, cross‑platform

ImageMagick is ideal when you need to Resize Images in Bulk across folders while converting formats and stripping metadata.

# Resize down to fit within 1600x1600, don't upscale, convert to JPEG at quality 85, strip metadata
mkdir -p out
magick mogrify -path out -resize "1600x1600>" -strip -filter Lanczos -quality 85 -colorspace sRGB *.jpg *.jpeg *.png

# Convert to WebP with resize and near-lossless quality
magick mogrify -path out -resize "1600x1600>" -strip -quality 82 -define webp:method=6 -colorspace sRGB -format webp *.jpg *.png

iPhone (Shortcuts) — quick mobile batch

Open Shortcuts → + → add:
- Select Photos (turn on Select Multiple)
- Resize Image (e.g., Width: 1600 px, Auto Height)
- Convert Image (JPEG or WebP if available)
- Save File (Ask Where to Save)
Run → choose photos → save resized copies to Files (keeps originals in Photos).

On iOS, Shortcuts can Resize Images in Bulk and save copies to Files.

Apple help: Shortcuts User Guide

Keep quality, color, and orientation correct

Aspect ratio: Use “Constrain proportions/Scale proportionally.” Crop only if you intend to change framing.
Don’t upscale: Check “Only shrink” (PowerToys/IrfanView) or use 1600×1600> in ImageMagick (the “>” prevents enlargement).
Color profile: Export the sRGB color profile. Stripping ICC profiles without converting can shift colors; most tools convert to sRGB by default.
Sharpen after downscale (optional): A light sharpen can restore crispness; ImageMagick’s Lanczos filter helps.
Orientation: Good tools apply EXIF rotation—if a result is sideways, rotate once and re‑export.

Naming and workflows (so galleries stay tidy)

Clear naming helps when you Resize Images in Bulk and need to track sizes at a glance.

Suffix convention: photo_1600w.jpg or product-blue-L_1200x.jpg makes sizes obvious.
Batch‑rename: Use OS tools or this guide: Rename Files in Bulk
Archive originals: Keep a full‑res “/originals” folder; export resized to “/web_1600w.”

Troubleshooting (real fixes)

Try these fixes if results look off after you Resize Images in Bulk:

My images look blurry on the site.
Start from higher‑res originals; export at 2× target display size for retina (e.g., intended 800px → upload 1600px). Avoid repeated resaves—re‑export from the original.
Colors changed after resizing.
Ensure output is sRGB. In ImageMagick, add -colorspace sRGB. In Preview/Photoshop‑like tools, export for web with sRGB conversion.
File size is still too big.
Reduce width first (e.g., 1600 → 1200). Then lower quality a bit (JPG/WebP 75–80%). Strip metadata. Switch to WebP if supported.
PNG photos are massive.
PNG is lossless—great for graphics, not photos. Convert photos to JPG/WebP unless you need transparency.
Batch job overwrote originals.
Always export to a new folder or enable “copy before” options (Automator/IrfanView). ImageMagick: use -path or a different output file name.

Helpful resources

Summary: fastest path by device

Use these workflows to Resize Images in Bulk quickly on any device:

Windows (batch): PowerToys → select images → right‑click Resize pictures → set width (e.g., 1600) → Only shrink → pick JPG/WebP quality.
Mac (batch): Preview → select all thumbnails → Tools → Adjust Size → set width → Export (JPG/WebP) with quality.
Online (non‑sensitive): Squoosh → Resize + quality; or BulkResizePhotos for many files client‑side.
iPhone (batch): Shortcuts → Select Photos → Resize Image (1600px wide) → Convert Image (JPEG/WebP) → Save File.

Once resized, keep names clean for easy uploads: Rename Files in Bulk. Need to bundle a set for someone? Skip email—share with a link: Share Large Files Safely.

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