About
px: pixels (absolute). rem: relative to root font (16px default). em: relative to parent. pt: typography (1pt = 1.333px). Use rem for global scaling. em for component-relative. px for fixed values (borders, exact sizes).
Formula
Frequently asked questions
How accurate is the px / rem / em Converter?
It applies the standard formula. Accuracy is limited only by your input precision. For decisions with material consequences (taxes, medical, legal, structural), use the result as a starting point and verify with a qualified professional in the relevant field.
Is the px / rem / em Converter free to use?
Yes. 100% free, no signup, no payment, no API key. The site is funded by display ads around the tool but not inside the calculation flow.
Are my inputs saved anywhere?
No. All inputs stay in your browser tab. Closing the tab discards them. The site uses Google Analytics for traffic measurement (anonymized) but the analytics never see what you type into the form.
Can I use the px / rem / em Converter on my phone?
Yes. The tool is responsive and tested on iOS Safari, Android Chrome, and major desktop browsers. Touch targets meet Apple's 44pt and Google's 48dp minimum.
Does the px / rem / em Converter work offline?
Yes. Once the page has loaded, it works without internet. The calculation runs in JavaScript on your device.
How do I report a bug or suggest improvement to the px / rem / em Converter?
Email hi@3tej.com with the URL of this page and a description of what you saw vs expected. We typically respond within 72 hours.
Can I share results from the px / rem / em Converter?
Take a screenshot or copy the output. The page doesn't generate shareable URLs for specific calculations - inputs stay in your browser only.
Why are the results different from another px / rem / em tool?
Most likely: different formula assumptions, different default values, different rounding rules, or different applicable rates. Check the methodology if both tools document it. Both can be valid for different scenarios.
Is the px / rem / em Converter accurate?
The px / rem / em Converter applies the standard formula for px / rem / em. Accuracy is limited only by your input precision. For decisions with material consequences, use the result as a starting point and verify with a qualified professional or the relevant official source.
Is the px / rem / em Converter free?
Yes. 100% free, no signup, no payment, no API key. The site is funded by display ads that appear around the tool but not inside the calculation flow.
Are my inputs saved?
No. Inputs stay in your browser tab. Closing the tab discards them. The site uses Google Analytics for traffic measurement (anonymized) but does not see what you type into the form.
How to use the px / rem / em Converter
The px / rem / em Converter is a browser-based tool that runs entirely on your device. Inputs you enter never reach a server - all calculations happen client-side in JavaScript. This means:
- Privacy: nothing is logged, sent, or stored by 3Tej. Inputs disappear when you close the tab.
- Speed: results update as you type. No network round trip.
- Offline use: once the page is cached, it works without internet.
- No signup: no account, no email, no rate limits.
Step by step
- Enter your inputs in the form above. Each field is labeled with its unit (currency, percent, kg, etc.) and the expected range.
- Read the result as it updates. The number reflects the formula commonly accepted in px / rem / em-related calculations.
- Adjust to see sensitivity: change one input at a time and watch how the output moves. This is the fastest way to understand which variable matters most.
- Copy or screenshot the result for later reference. The page state persists for the session if your browser allows it.
When you would use this
- Quick estimates: when you need a number now and don't want to open a spreadsheet.
- Sensitivity analysis: testing how a result changes as inputs vary, before committing to a real-world decision.
- Comparison: running the same calculation with different inputs to compare options side by side.
- Learning: building intuition for how the underlying math behaves.
- Documentation: capturing a snapshot of inputs and outputs at a point in time.