About
UV Index 0-2: low. 3-5: moderate. 6-7: high. 8-10: very high. 11+: extreme. Fitzpatrick skin types I-VI. SPF 30 blocks ~97% of UVB; SPF 50 blocks 98%. Both need reapplication every 2 hr or after swimming.
Formula
Frequently asked questions
How accurate is the UV Index + Sunscreen?
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 UV Index + Sunscreen 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 UV Index + Sunscreen 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 UV Index + Sunscreen 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 UV Index + Sunscreen?
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 UV Index + Sunscreen?
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 uv index + sunscreen 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 UV Index + Sunscreen accurate?
The UV Index + Sunscreen applies the standard formula for uv index + sunscreen. 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 UV Index + Sunscreen 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 UV Index + Sunscreen
The UV Index + Sunscreen 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 UV Index + Sunscreen-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.