Image Aspect Ratio & Resize Calculator
Simplify aspect ratios (e.g., 1920×1080 → 16:9), compute missing dimensions, and get exact Fit/Fill (contain/cover) math. Includes DPI/PPI conversions and megapixels. No uploads—private & client‑side.
Simplified ratio
Solved dimensions
Megapixels
Tip: 4:5 and 1:1 work well for Instagram; 9:16 for Reels/Shorts; 16:9 for YouTube thumbnails.
Scaled size
Padding / Crop
Scale factor
Fit keeps everything visible with bars/padding; Fill covers target but crops excess.
Printed size
Megapixels
Pixels ÷ DPI = inches (or cm/mm). For quality photo prints, 240–300 DPI is typical.
Image Aspect Ratio Calculator & Resize Calculator (Free Online)
Need the right aspect ratio for thumbnails, Reels/Shorts, or prints? This free image aspect ratio calculator instantly simplifies ratios (e.g., 1920×1080 → 16:9), solves missing dimensions, and computes Fit vs Fill (contain/cover) math with exact padding or crop values. It also converts pixels ↔ inches/cm at DPI, and shows megapixels. Fast, private, and client-side.
Try the Image Ratio & Resize Tool
Use the calculator above to:
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Convert width × height → simplified ratio
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Get height from width & ratio (or width from height & ratio)
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Calculate Fit (letterbox/padding) or Fill (cover/crop) for any target size
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Convert pixels to inches/cm at 72/96/240/300 DPI, with megapixels
How to Use (Step-by-Step)
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Enter width & height (or pick a preset: 1:1, 4:5, 16:9, 9:16, 3:2).
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Choose Solve for Width or Solve for Height to keep your ratio.
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Open Fit / Fill and enter original → target to get scaled size and padding/crop.
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Use DPI/PPI to convert pixels → print size (inches/cm/mm) and check megapixels.
Fit vs Fill (Contain vs Cover)
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Fit (Contain): scales the image to fit completely inside the target; you may get letterboxing/padding.
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Fill (Cover): scales the image to cover the target fully; edges beyond the frame are cropped.
Use Fit when you must show the entire image (e.g., galleries). Use Fill for banners, thumbnails, and reels covers that must fill the frame.
Popular Sizes & Ratios (Quick Reference)
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YouTube Thumbnail: 1280×720 → 16:9
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Instagram Square Post: 1080×1080 → 1:1
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Instagram Portrait (Feed): 1080×1350 → 4:5
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Reels / TikTok / Shorts (Vertical): 1080×1920 → 9:16
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Facebook Cover Photo: 820×312 (≈ 2.63:1)
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Twitter/X Header: 1500×500 → 3:1
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LinkedIn Cover: 1584×396 → 4:1
Tip: For sharp social uploads, stick to native platform ratios. If your image doesn’t match, use Fit/Fill to plan exact padding or crop before exporting.
DPI, PPI & Printing — What to Know
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Pixels are screen dimensions; DPI/PPI define print density.
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Pixels ÷ DPI = inches (then × 2.54 for cm).
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For photo prints, 240–300 DPI is a common sweet spot. Lower DPI can work for large wall prints viewed from farther away.
FAQs (Image Aspect Ratio & Resize)
How do I calculate aspect ratio from pixels?
Divide both width and height by their GCD (greatest common divisor). Example: 1920×1080 ÷ 120 → 16:9.
How do I resize without cropping?
Use Fit (Contain) to maintain the whole image. The result shows scaled size and the padding needed to reach the target.
How do I fill a frame for thumbnails or reels?
Use Fill (Cover). The tool shows the scaled size and the crop needed on X/Y to hit the exact target.
What’s the best size for a YouTube thumbnail?
1280×720 (16:9) is the standard; keep text large, safe margins, and high contrast.
What ratio is best for Instagram Reels or TikTok?
9:16 (vertical). Use 1080×1920 for crisp, platform-native output.
How do I convert pixels to inches for printing at 300 DPI?
Inches = pixels ÷ 300. For example, 3000×2400 px prints at 10×8 in at 300 DPI.