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Sunscreen Quantity Calculator

Work out sunscreen quantity instantly with clear inputs, formula shown and shareable results.

About Sunscreen Quantity Calculator

Applies the regulatory test dose of 2 mg per square centimetre to the exposed skin area, which is what the labelled SPF actually assumes.

Formula

Application quantity

Grams = exposed area (cm2) x 2 mg/cm2 / 1000; a full adult body of 1.8 m2 needs about 36 g, roughly seven teaspoons

Worked example

With the default values below, Sunscreen Quantity Calculator returns Sunscreen per application of 21.6. Change any input above and every figure here is recalculated in your browser.

Inputs used

Skin area to coveraccepts 0.2–3 m2
1.8 m2
Share of that area exposedaccepts 5–100 %
60 %
Applications per dayaccepts 1–10
4

Results

Sunscreen per application
21.6 g
Sunscreen per day
86.4 g
Teaspoons per application
4.32
Days from a 200 mL bottle
2.3

Step by step

  1. 1Values used
  2. 2Application quantity
  3. 3Sunscreen per application= 21.6 g
  4. 4Sunscreen per day= 86.4 g
  5. 5Teaspoons per application= 4.32
  6. 6Days from a 200 mL bottle= 2.3

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.
  • This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.

Frequently Asked Questions

Why does quantity matter so much?

Applying half the test dose gives far less than half the labelled protection, because SPF does not scale linearly with thickness.

How often should it be reapplied?

Every two hours, and immediately after swimming, towel drying or heavy sweating.

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