Calculating your value in pixels is straightforward once you know the REM to PX formula and what each input means. This guide explains the method in plain language, walks through a manual calculation, and gives worked examples you can follow — then you can do it instantly with the REM to PX Calculator.
What is REM to PX?
The REM to PX calculation tells you your value in pixels from a few simple inputs. The figure you are solving for here is the value in pixels.
The REM to PX formula
The core formula is:
Value in pixels = Value in rem × Root font sizeHere is what each input means:
- Value in rem — a number. Example: 2.
- Root font size — a value measured in px. Example: 16 px.
How to calculate it step by step
- Write down the value in rem (for example, 2).
- Write down the root font size (for example, 16 px).
- Apply the formula above to get your value in pixels.
- Double-check the result with the REM to PX Calculator.
Worked examples
Example 1
| Input / Output | Value |
|---|---|
| Value in rem | 2 |
| Root font size | 16 px |
| Value in pixels | 32.00 |
With value in rem of 2 and root font size of 16 px, the value in pixels works out to 32.00.
Example 2
With value in rem of 4 and root font size of 16 px, the value in pixels works out to 64.00.
| Result | Value |
|---|---|
| Value in pixels | 64.00 |
Example 3
With value in rem of 1 and root font size of 16 px, the value in pixels works out to 16.00.
| Result | Value |
|---|---|
| Value in pixels | 16.00 |
Tips for an accurate result
- Keep your units consistent — mixing, say, months with years or grams with kilograms is the most common source of error.
- Round only at the very end. Rounding inputs early can shift the final answer noticeably.
- Re-run the numbers whenever an input changes, rather than estimating from an old result.
Prefer not to do the maths by hand? — the REM to PX Calculator does it instantly, for free, with the formula and a worked example built in.
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