Sun Session — UV Balance

Pick Location & UV Index

UV Index

—

Temperature

—

context only

Location

—

UV Index below 3 — meaningful vitamin D synthesis is minimal at this level.

or enter UV Index manually

I know my UV Index:

Hourly UV chart requires a detected location. Burn-time and vitamin D estimates work with a manually entered value.

Today's UV Forecast

Solid: actual UV Index · Dashed: clear-sky max · Powered by Open-Meteo.

Skin Type & Exposure

Fitzpatrick Skin Type What is this?

MED: Type I = 2.0 SED · II = 3.0 · III = 4.5 · IV = 6.0 · V = 8.0 · VI = 10.0

Body Area Exposed What is this?

Upper body

Lower body

Extras Hat / cap (covers ~5%)

Check every region that is exposed (not covered by clothing). Regions total 100% when all selected.

Head & neck 9% Chest (front) 9% Abdomen (front) 9% Upper back 9% Lower back 9% Right arm 9% Left arm 9% Right thigh 9% Left thigh 9% Right lower leg 9% Left lower leg 9% Genitalia 1%

0% selected

% of body surface exposed

Enter 0 (fully clothed) to 100 (completely bare).

Using clothing estimate: 35% exposed

Sun Exposure Orientation

Affects vitamin D estimate only — not burn time.

Estimates for your conditions

Burn Time

—

minutes to first sunburn

Vitamin D / hr

—

IU per hour (approx)

UV Risk

—

at current UV Index

Time to ~1,000 IU

—

based on skin, BSA & orientation

Burn time depends on skin type and UV Index only. Vitamin D estimates change with body area and orientation.

Pick Timer Mode

Timer runs until your estimated burn threshold (90% MED) is reached, then sounds an alarm.

Session duration (minutes)

Vitamin D target (IU)

Start Session

00:00

session time

0% 0% 100% MED

UV Dose

of your MED

Remaining

—

until burn

Vitamin D

IU est.

Today's Running Totals (all sessions)

IU Vitamin D

UV Dose (MED)

✅

Session Saved!

This Session

UV Dose

of your MED

Vitamin D

IU est.

☀️ Sun Session

Pick Location & UV Index

Today's UV Forecast

Skin Type & Exposure

Estimates for your conditions

Pick Timer Mode

Start Session