CSS Fluid Typography Calculator
Generate a responsive CSS clamp() expression from a minimum and maximum font size at two viewport widths. The output is a CSS starting point you can paste into a stylesheet.
How to use this calculator
- Enter the minimum font size (px) using the units shown beside the field.
- Enter the maximum font size (px) using the units shown beside the field.
- Enter the minimum viewport width (px) using the units shown beside the field.
- Review the calculated values and check that the assumptions match your scenario.
- Change one input at a time when comparing scenarios so you can see which assumption drives the result.
Formula and assumptions
Linear font-size relation between the two viewport anchors, clamped to the entered minimum and maximum sizes.
- Check the output with your design’s font family, line height, accessibility preferences and intermediate screen widths.
- The result is computed from the values you provide; it does not fetch external rates, live account data or local rules.
Worked examples
Worked example
A 16px minimum at 360px wide and 30px maximum at 1,200px wide produces a clamp expression with a fluid viewport term.
Example inputs: Minimum font size (px) = 16, Maximum font size (px) = 30, Minimum viewport width (px) = 360, Maximum viewport width (px) = 1200.
Compare the displayed output with your own measurements before using it in a decision.
Understanding the result
Check the output with your design’s font family, line height, accessibility preferences and intermediate screen widths.
Results are estimates based on the stated model. If the situation depends on measured conditions or contractual specifications, use those source values rather than typical assumptions.
Important notes
Check the output with your design’s font family, line height, accessibility preferences and intermediate screen widths.
Frequently asked questions
What formula does this calculator use?
It uses the method described above: Linear font-size relation between the two viewport anchors, clamped to the entered minimum and maximum sizes.
What should I verify before relying on the result?
Check the output with your design’s font family, line height, accessibility preferences and intermediate screen widths.
Can I compare different scenarios?
Yes. Change the inputs while keeping units and definitions consistent, and record the assumptions used for each scenario.
Affiliate recommendations
Tools related to CSS Fluid Typography Calculator
These tools are selected for the calculator topic. The Calc Studio may earn a commission from purchases made through affiliate links.
- WebHosting UK Visit partner ↗
Web hosting, domains, and website infrastructure for businesses and websites.
- Ultra Web Hosting Visit partner ↗
Web hosting and website infrastructure for websites and online businesses.
See the Affiliate Disclosure for details.
Related calculators
- Responsive Image Dimensions Calculator — Calculate a proportional image height and pixel dimensions for a target CSS width and device pixel ratio.
- Audio File Size Calculator — Estimate encoded audio file size from duration and average bitrate for podcast, music and storage planning.
- Print Bleed Size Calculator — Calculate artwork dimensions including bleed beyond each trim edge and the expanded document area.
- Video Bitrate and File Size Calculator — Estimate video file size from duration, video and audio bitrates and an overhead allowance.
- A/B Test Sample Size Calculator — Estimate per-variant sample size for a two-sided conversion-rate A/B test using a normal approximation, baseline rate and relative minimum detectable lift.
- Average Database Record Size Calculator — Estimate average stored size per record from a dataset size and record count.
Related explanations
Learn the method behind the number or compare the terminology before using the calculator.
- Percentage Change vs Percentage Difference — Understand the difference between percentage change and percentage difference, including when each formula is appropriate.
- How to Calculate Days Between Dates — Learn how date intervals work, including leap years and inclusive vs exclusive day counting.
- Standard Deviation — Understand standard deviation as a measure of spread and the difference between population and sample standard deviation.
This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.