Free Photo Size Calculator
Enter your image dimensions and settings to estimate megapixels, print size, and expected file size.
What this photo size calculator tells you
Photo files can be confusing because several numbers affect final quality: width, height, DPI, color depth, and compression. This calculator combines all of them into practical outputs you can use immediately:
- Megapixels (sensor/output resolution)
- Uncompressed size (editing/storage requirement)
- Estimated export size for JPEG, PNG, WebP, HEIC, and TIFF
- Print dimensions in inches and centimeters
How to use it correctly
1) Enter pixel dimensions
Use your image’s actual width and height in pixels. Example: 6000 × 4000 from many modern cameras.
2) Set DPI for printing
DPI does not change pixel count, but it changes how large the photo can be printed. 300 DPI is standard for sharp photo prints, while 150 DPI is acceptable for larger posters viewed from farther away.
3) Choose color channels and bit depth
RGB 8-bit is typical for web and everyday photo delivery. 16-bit is common in pro editing workflows because it preserves more tonal data.
4) Pick output format and quality
JPEG and WebP are usually best for photos online. PNG is lossless but often larger for photographic images. TIFF is best for archival/editing but huge.
Quick formulas behind the calculator
- Megapixels = (Width × Height) ÷ 1,000,000
- Uncompressed bytes = Width × Height × Channels × (Bit Depth ÷ 8)
- Print size (inches) = Pixels ÷ DPI
- Print size (cm) = Inches × 2.54
Common resolution targets
For web and social media
- Blog hero image: 1600 × 900
- Instagram portrait: 1080 × 1350
- YouTube thumbnail: 1280 × 720
- High-quality website banner: 1920 × 1080 or larger
For print
- 4 × 6 inch print at 300 DPI: 1200 × 1800 px
- 8 × 10 inch print at 300 DPI: 2400 × 3000 px
- 11 × 14 inch print at 300 DPI: 3300 × 4200 px
- A3 print at 300 DPI (approx): 3508 × 4961 px
Practical tips to reduce file size without wrecking quality
- Resize to final display dimensions before export.
- Use JPEG quality around 75–85 for a strong quality/size balance.
- Try WebP for web delivery; it often beats JPEG in size.
- Keep TIFF/PNG masters for editing, then export lighter delivery copies.
- Strip unnecessary metadata when delivering final web images.
FAQ
Does higher DPI increase file size?
Not by itself. File size mainly depends on pixel dimensions, color data, and compression. DPI mainly affects print dimensions.
Why is the export size only an estimate?
Compression efficiency depends on image content. Smooth skies and simple backgrounds compress better than detailed textures and noise.
What is best for websites: JPEG, PNG, or WebP?
For most photos, WebP or JPEG are best. PNG is usually better for logos, icons, and screenshots with sharp edges.