We created this **sunscreen calculator** to help determine the **appropriate amount** of sunscreen needed for **effective protection** against harmful **UV rays** by considering **BSA**, **sun exposure time**, and the **SPF **of the sunscreen.

Let’s say you’re planning a **beach day**. A sunscreen calculator might consider:

- Your height and weight to estimate body surface area
- The duration of your beach visit
- The SPF of your sunscreen
- The intensity of UV radiation at your location

## Sunscreen Calculator

Height (cm) | Weight (kg) | BSA (m²) | Single Application (ml) | Daily Usage (3 applications) | 2-Week Usage (ml) |
---|---|---|---|---|---|

160 | 60 | 1.63 | 32.6 | 97.8 | 1,369 |

175 | 75 | 1.91 | 38.2 | 114.6 | 1,604 |

180 | 80 | 2.00 | 40.0 | 120.0 | 1,680 |

165 | 55 | 1.60 | 32.0 | 96.0 | 1,344 |

190 | 90 | 2.19 | 43.8 | 131.4 | 1,840 |

## Sunscreen Calculation Formula

The formula for calculating sunscreen usage is:

Amount of sunscreen (in ml) = Body Surface Area (in cm²) × 2 mg/cm²

This formula is based on the **standard recommendation** of applying 2 mg of sunscreen per square centimeter of skin.

For an average adult with a body surface area of 1.8 m² (18,000 cm²): 18,000 cm² × 2 mg/cm² = 36,000 mg =

36 mlof sunscreen

## How do you calculate how much sunscreen you need?

To calculate your sunscreen needs:

**Estimate your body surface area (BSA)**: Use the**Mosteller formula**: BSA (m²) = √[(Height (cm) × Weight (kg)) / 3600]**Convert BSA to square centimeters**: Multiply by 10,000**Apply the 2 mg/cm² rule**: Multiply your BSA in cm² by 2**Convert mg to ml**: Divide the result by 1000

For a person 170 cm tall weighing 70 kg:

BSA = √[(170 × 70) / 3600] =

1.81 m²1.81 × 10,000 =

18,100 cm²18,100 × 2 =

36,200 mg36,200 / 1000 =

36.2 ml

This person should apply approximately **36 ml** of sunscreen for **full-body coverage**.

## Why do we need sunscreen?

Sunscreen is **crucial** for protecting our skin from the **harmful effects** of UV radiation, including:

**Sunburn**: Immediate reddening and pain in the skin**Premature aging**: Wrinkles, age spots, and loss of skin elasticity**Skin cancer**: Increased risk of melanoma and non-melanoma skin cancers**Immunosuppression**: Weakening of the skin’s immune function**Eye damage**: Increased risk of cataracts and macular degeneration

## How much sunscreen for 2 weeks?

- Assuming 3 applications per day: 36 ml × 3 =
**108 ml daily** - For 2 weeks: 108 ml × 14 =
**1,512 ml**or about**1.5 liters**

To calculate sunscreen needs for a **two-week period**:

Determine daily usage (as calculated earlier)

Multiply by the number of applications per day (typically 2-3)

Multiply by 14 days

This amount ensures **proper coverage** for a two-week period, but actual usage may vary based on factors like activities and sun exposure.

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