Convert Tools
Convert CSS units, length, data size, time, color, and number bases. Formulas and assumptions are on each page.
9 tools · 100% browser-based · No uploads · No signup
About these Convert tools
Converters cover CSS units, physical length, screen resolution and DPI, time, data size (SI vs IEC), angles, number bases, typography scales, and color models. Results update as you type. They are calculators with the assumptions spelled out, not magic that knows your design token file.
px to rem needs a root font size. cm to px needs a DPI. MB vs MiB is a real disagreement between disk vendors and RAM. Color conversions between HEX, RGB, and HSL are straightforward; perceptual uniformity is not.
Tools in this category
CSS Units
Convert between px, rem, em, vw, vh, pt, and percentages, with live results.
Length
Convert between mm, cm, inches, feet, meters, km, and pixels at any DPI.
Screen / Resolution
Work out screen dimensions, DPI, and PPI from a resolution — or the other way around.
Time
Convert between milliseconds, seconds, minutes, hours, and days in human-readable form.
Data Size
Convert between bytes, KB, MB, GB, and TB using decimal (SI) or binary (IEC) units.
Angle
Convert between degrees, radians, gradians, and turns, with a visual arc preview.
Number Base
Convert between binary, decimal, hexadecimal, and octal, with a bit-by-bit view.
Typography
Convert px, pt, em, and rem for typography, and preview line-height and type scale.
Color
Convert between HEX, RGB, RGBA, HSL, HSLA, and HSB, with a live color preview.
How these tools run in your browser
Each converter applies a documented formula. CSS px here follows the CSS reference pixel at the DPI you set (default 96). Data size lets you pick SI (1000) or IEC (1024). Color conversion uses standard sRGB channel math, not a color-managed CMS.
Common Use Cases
- Convert 16px to rem at a 16px root
- Explain why a 1 inch print is not 96 CSS pixels on a 2x display
- Check whether a file size is decimal MB or binary MiB
- Translate a hex brand color to HSL for a design token
- Convert hex 0xFF to decimal while debugging a bit flag
Common Mistakes
Frequently Asked Questions
CSS pixels are not physical millimeters unless the environment is calibrated. Set DPI to your display if you care about print-ish sizes.
Storage marketing often uses GB (10^9). Windows RAM and many developer tools use GiB (2^30). Use the data size tool and pick the convention your OS shows.
8-bit HEX/RGB round-trips. Going through HSL and back can move a channel by one bit. For brand colors, keep the original HEX.