1. What is Sunscreen Calculation?

The sunscreen calculation determines the proper amount of sunscreen needed to achieve the advertised SPF protection based on body surface area and standard application density.

2. How Does the Calculator Work?

The calculator uses the simple formula:

Where:

• \( Body\ area \) — The surface area to be protected (in cm²)
• \( Application\ density \) — Standard sunscreen application density (typically 2 mg/cm²)

Explanation: The calculation ensures you apply enough sunscreen to get the full SPF protection shown on the product label.

3. Importance of Proper Sunscreen Amount

Details: Applying insufficient sunscreen dramatically reduces protection. Studies show most people apply only 20-50% of the recommended amount.

4. Using the Calculator

Tips: Measure your body area accurately. The standard application density is 2 mg/cm² for proper SPF protection.

5. Frequently Asked Questions (FAQ)

Q1: Why is 2 mg/cm² the standard density?
A: This is the amount used during SPF testing. Less than this reduces protection exponentially.

Q2: How do I estimate my body area?
A: Average adult body surface is about 17,000 cm² (full body). Face alone is about 600 cm².

Q3: Does this work for all sunscreen types?
A: Yes, the calculation applies to creams, lotions, and sprays (though sprays are harder to measure).

Q4: What if I'm applying to multiple areas?
A: Calculate each area separately or sum all areas before multiplying by density.

Q5: How often should I reapply?
A: Every 2 hours, or immediately after swimming/sweating, regardless of SPF.