Health · official-source review · reviewed 2026-10-10
Most people apply 25–50% of the amount of sunscreen tested for the labeled SPF, getting much less protection.
Calculate the amount of sunscreen needed for adults and kids for hours outside.
Adults applying sunscreen for themselves and children for a day outdoors.
Use the source document or official route that applies to your situation. This guide does not contact another person or verify external information.
Count adults and kids and how many hours you will be outside.
About one ounce (a shot glass, ~6 tsp) per adult per application.
Reapply after swimming, heavy sweating, or every two hours.
Pack more than you think; under-application is the main mistake.
Two adults and one kid outside for 4 hours need about 9 teaspoons (45 ml) total for two applications.
Use your own source and details. The example is not a record about a real person or organization.
American Academy of Dermatology · reviewed 2026-10-10
What this source supports: Most adults need about one ounce (enough to fill a shot glass) of sunscreen to cover exposed skin for one application, with reapplication every two hours.
Source limit: Individual needs vary by size and clothing; seek shade during peak hours too.
These sources support the statements above. They do not show that every person needs this guide. They do not show a specific result.
This App gives general volume guidance. It is not medical advice; reapply every 2 hours or after swimming/sweating.
Individual needs vary by size and clothing; seek shade during peak hours too.
Use current instructions from the responsible organization. This guide is a planning aid, not an official decision or a substitute for qualified advice.
Calculate sunscreen volume needed for adults and kids over hours outside.
This is general guidance. Reapply as directed and seek shade during peak hours.
You enter every number yourself. The sources support the method and the limits. They do not produce a result for your specific case. Keep the original documents next to the sheet you build.
The App computes the worked example with your own numbers, in your browser.
APP 1
Calculate sunscreen volume needed for adults and kids over hours outside.
Free · no account · no upload
Open Sunscreen Amount CalculatorThe App runs in this browser. It does not send or save entries. Copy, download, or print only when you choose.
This guide uses short, direct instructions as an ASD-STE100-style writing target. It is not a formal certification.
Companion App: Sunscreen Amount Calculator. It runs in this browser and does not upload your entries.
This guide is edited for clarity and checked against the sources it links. It is not a substitute for official instructions or qualified advice. A linked source does not show that every person needs this guide.