Percent to REM Converter

Convert CSS percent values to REM. For root-relative sizing, 100% = 1rem, 150% = 1.5rem, 75% = 0.75rem.

Last updated: May 21, 2026

Formula: rem = % ÷ 100(100% = 1rem)

Percent Values

Separate values with commas or newlines. "%" suffix is optional.

REM Output

62.5% → 0.625rem 75% → 0.75rem 100% → 1rem 150% → 1.5rem

Reference table

%	REM	%	REM	%	REM
25%	0.25rem	50%	0.5rem	62.5%	0.625rem
75%	0.75rem	87.5%	0.875rem	100%	1rem
112.5%	1.125rem	125%	1.25rem	137.5%	1.375rem
150%	1.5rem	175%	1.75rem	200%	2rem
225%	2.25rem	250%	2.5rem	300%	3rem
350%	3.5rem	400%	4rem	500%	5rem

Client-Side Processing

Input Data Stays on Device

Instant Local Execution

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What is Percent to REM Converter?

CSS percent and REM share the same numerical ratio when used for root-level font sizes: 100% equals 1rem. The browser default sets both to 16px. The formula is simply: **rem = % ÷ 100**.

This conversion is useful when a design system uses percent-based font sizes (e.g. `font-size: 62.5%` on the root to make 1rem = 10px) and you need to express values in REM, or when migrating a percent-based stylesheet to use REM.

How to Use Percent to REM Converter

Enter one or more percent values (comma or newline separated)

Copy the REM output or use the reference table

The formula is always: rem = % ÷ 100

Common Use Cases

Developers migrating percent-based font sizes to REM for a consistent type scale.
Teams converting legacy CSS that uses percent for root font sizes to modern REM.
Front-end engineers comparing percent and REM values in a design token system.
Students learning the numerical relationship between percent and REM in CSS.

Example Input and Output

Convert common CSS percent values to REM.

Percent values

REM output

62.5% → 0.625rem
75% → 0.75rem
100% → 1rem
150% → 1.5rem

Privacy

All conversions run in your browser. No data is sent to any server.

Frequently Asked Questions

Is 100% always 1rem?

Numerically yes — the ratio is always 100% = 1rem. However, percent for font-size is relative to the parent element, while rem is relative to the root. On the root element they're equivalent; on nested elements they differ in inheritance behavior.

What is the 62.5% trick?

Setting html { font-size: 62.5% } makes 1rem = 10px (62.5% of 16px), so 2.4rem = 24px — easier mental math. This converter helps you see all percent-to-rem relationships at a glance.

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