Big Ideas,
Real Impact.
SunBeast Protection Score
Tap each body zone to show what's protecting it. Your SPS updates live and adapts to the UV index — the stronger the sun, the more coverage it takes to stay in the green.
Your SunBeast Protection Score
Tap a zone
11 zones · weighted by riskZone
Nothing selected yet = fully unprotected. Zones start exposed and move toward armored as you add cover.
How the score works & the science behind it
The formula
Every zone carries an importance weight from the clinical literature. Your chosen protection blocks a share of UV, so each zone still transmits the rest. We compute a residual effective UV index reaching your prioritized skin, then convert it to a 0–100 score:
- Weighted transmission = Σ(weight × UV that gets through) ÷ total weight
- Residual UV (R) = UV index × weighted transmission
- SPS = 100 × (1 − R ÷ 8), floored at 0
The "÷ 8" is the calibration point: at a Very High UV of 8, fully unprotected skin scores 0. Because R scales with the UV index, the same outfit scores lower on a fierce-sun day than a mild one — so a high score always takes more coverage when the sun is stronger.
Zone weights & rationale
| Zone | Weight | Why it's weighted this way |
|---|
Coverage factors (share of UV blocked)
| Protection | Blocks | Basis |
|---|---|---|
| UPF 50+ / tight dark fabric | 98% | UPF 50 = 1/50 transmission; consistent, no reapplication, covers UVA+UVB. |
| UV400 / wraparound sunglasses | 99% | UV400 lenses block essentially all UV to 400 nm; wrap styles cut side entry. |
| Hat / brim / shade | 92–95% | Physical shading of upward-facing surfaces (scalp, ears, face). |
| Sunscreen SPF 30+ | 90% | Labels test ~97–98%, but typical people apply ¼–½ the tested amount (effective protection ≈ √SPF), so credited below UPF and clothing. Needs reapplication. |
| Light / translucent fabric | 80% | Thin, loose or sheer weave ≈ UPF 5–7; drops further when wet (a wet cotton tee ≈ UPF 3). |
| Sunscreen SPF 15–29 | 75% | Lower ceiling and same real-world under-application penalty. |
| Basic / fashion sunglasses (unrated) | 55% | Tint without a UV rating gives partial, inconsistent protection. |
| Bare skin | 0% | No barrier. |
Score bands
| 85–100 · Apex | Minimal risk for the current conditions. |
| 70–84 · Shielded | Low risk; small gaps remain. |
| 50–69 · Patchy | Moderate risk; meaningful areas exposed. |
| 30–49 · Exposed | High risk; key high-value zones unprotected. |
| 0–29 · Scorched | Very high risk for these conditions. |
Selected references
- Bulliard J-L, Levi F, et al. Site distribution of different types of skin cancer. Int J Cancer, 1996 — face shows a >20-fold excess incidence per unit area for BCC/SCC.
- IARC / WHO. Solar and Ultraviolet Radiation. — nose, tops of ears and forehead receive up to ~10× the UVB of shaded sites.
- Schmalwieser AW, et al. Erythemal UV exposure during jogging. Photochem Photobiol, 2025/26 — the top of the shoulder receives ~80% of ambient UV (up to 110%).
- Sex-based differences in cutaneous SCC distribution — head/neck predominates in men, lower extremities in women.
- Osterlind A, et al. Melanoma in Denmark. — back/trunk highest in men, legs in women.
- ASTM/AATCC UPF standards; skincancer.org — UPF 15/30/50 transmit 6.7% / 3.3% / 2%.
- Real-world sunscreen application studies — typical use ≈ ¼–½ the tested thickness, effective SPF ≈ √(labelled SPF).
Built for the SunBeast toolkit · protect the beast, stay in the sport for the long run.