Font Size Calculator
Enter a pixel value to see conversions to rem, em, vw, and other units.
How to Use the CSS Font Size Calculator
Using the CSS Font Size Calculator is straightforward:
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Enter Your Values
Input the required numbers and parameters into the calculator fields. Each field is clearly labeled β simply type your values or use the spinner controls to adjust them.
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Configure Options
Select any additional options such as computation mode, currency, time period, or precision level. The calculator updates automatically as you change values.
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View the Results
The calculated result is displayed instantly with clear formatting. You can Copy the result to your clipboard or adjust input values to see how different scenarios affect the outcome.
Frequently Asked Questions
How do I convert px to rem?
Enter the pixel value and root font size. rem = px / root-font-size. For example, 32px with a 16px root = 2rem.
What is the difference between rem and em?
rem is relative to the root (html) font size. em is relative to the parent element's font size. This tool calculates both simultaneously.
How is vw calculated?
vw = (px / viewport-width) * 100. For example, 16px at 1440px viewport = 1.11vw.
What is the default root font size?
The default root font size is 16px (standard browser default). You can adjust it to match your project.
Can I change the viewport width?
Yes. Adjust the viewport width slider to see how vw units change at different screen sizes.