Font Scaling Calculator
Practice and calculate font scaling with our free tool. Includes worked examples, visual aids, and learning resources.
Formula
Font Size = Base Size x Ratio^Level
Each level in the type scale is calculated by multiplying the base font size by the scale ratio raised to the power of the level number. Level 0 equals the base size, positive levels generate heading sizes, and negative levels generate smaller text sizes. The ratio determines how dramatically sizes change between levels.
Worked Examples
Example 1: Blog Design Type Scale
Problem: A web designer needs a type scale for a blog with 16px base size using the Major Third ratio (1.25) with 6 heading levels. What are the font sizes?
Solution: Base: 16px, Ratio: 1.25 (Major Third)\nh6: 16 x 1.25^0 = 16.00px (1rem)\nh5: 16 x 1.25^1 = 20.00px (1.25rem)\nh4: 16 x 1.25^2 = 25.00px (1.5625rem)\nh3: 16 x 1.25^3 = 31.25px (1.9531rem)\nh2: 16 x 1.25^4 = 39.06px (2.4414rem)\nh1: 16 x 1.25^5 = 48.83px (3.0518rem)\nSmall text: 16 x 1.25^-1 = 12.80px (0.8rem)
Result: Scale: 12.8px / 16px / 20px / 25px / 31.25px / 39.06px / 48.83px
Example 2: Fluid Typography for Responsive Design
Problem: Create fluid font sizes for h1 (48.83px max) that scales down to 28px minimum between 320px and 1200px viewport widths.
Solution: Min size: 28px (1.75rem), Max size: 48.83px (3.052rem)\nViewport range: 1200 - 320 = 880px\nSize range: 48.83 - 28 = 20.83px\nvw coefficient: (20.83 / 880) x 100 = 2.367vw\nCSS: font-size: clamp(1.75rem, 2.37vw + 1.75rem, 3.052rem)\nAt 320px viewport: 28px (minimum)\nAt 760px viewport: ~38px (midpoint)\nAt 1200px viewport: 48.83px (maximum)
Result: CSS: clamp(1.75rem, 2.37vw + 1.75rem, 3.052rem) | Fluid range: 28px to 48.83px
Frequently Asked Questions
What is the difference between em, rem, and px for font sizing?
Pixels (px) are absolute units that provide precise control but do not scale with user preferences or parent elements. Rems are relative to the root HTML element font size (typically 16px), making them ideal for maintaining consistent proportions throughout a site while respecting user accessibility settings. Ems are relative to the parent element font size, causing compounding effects when nested. For type scales, rem units are generally preferred because they maintain proportional relationships regardless of nesting depth. Using rems also allows users who adjust their browser default font size to see all text scale proportionally.
How do I choose the right base font size for my project?
The base font size for body text on the web should generally be 16-18px for desktop and 14-16px for mobile. Research on readability consistently shows that smaller body text increases reading fatigue and decreases comprehension. The default browser font size of 16px has become the de facto standard for good reason. For content-heavy sites like blogs and documentation, consider 18px as your base. For data-dense applications and dashboards, 14px may be appropriate. Always test your base size with actual content at realistic reading distances, and ensure your base size meets WCAG accessibility guidelines for minimum text size.
Does Font Scaling Calculator work offline?
Once the page is loaded, the calculation logic runs entirely in your browser. If you have already opened the page, most calculators will continue to work even if your internet connection is lost, since no server requests are needed for computation.
How do I get the most accurate result?
Enter values as precisely as possible using the correct units for each field. Check that you have selected the right unit (e.g. kilograms vs pounds, meters vs feet) before calculating. Rounding inputs early can reduce output precision.
How accurate are the results from Font Scaling Calculator?
All calculations use established mathematical formulas and are performed with high-precision arithmetic. Results are accurate to the precision shown. For critical decisions in finance, medicine, or engineering, always verify results with a qualified professional.
Can I share or bookmark my calculation?
You can bookmark the calculator page in your browser. Many calculators also display a shareable result summary you can copy. The page URL stays the same so returning to it will bring you back to the same tool.