Percent transmitted to half-value layers
Type a value in % to get it in HVL instantly.
5.059HVL
That's 1.52× as thick as a lead apron against diagnostic X-rays, while an X-ray room wall is 1.38× thicker. About 3% of the radiation still gets through.
Convert the other way: HVL to %
What it means
How much gets stopped?
Thicknesses are for a 1 MeV gamma beam. Half-value layers change with photon energy, so a shield that works for one isotope may not for another.
The math
How to convert % to HVL
Each layer halves what is left: transmitted = 100 ÷ 2^layers percent, and back again layers = log₂(100 ÷ %). A tenth-value layer is 3.32 half-value layers.
Example: 3 % = 5.05889 HVL.
Every unit
Your shielding in every unit
Tables
% to HVL conversion table
| % | HVL |
|---|---|
| 0.5 % | 7.64386 HVL |
| 1 % | 6.64386 HVL |
| 2 % | 5.64386 HVL |
| 3 % | 5.05889 HVL |
| 4 % | 4.64386 HVL |
| 5 % | 4.32193 HVL |
| 7 % | 3.8365 HVL |
| 10 % | 3.32193 HVL |
| 13 % | 2.94342 HVL |
| 20 % | 2.32193 HVL |
HVL to % conversion table
| HVL | % |
|---|---|
| 0.5 HVL | 70.7107 % |
| 1 HVL | 50 % |
| 2 HVL | 25 % |
| 3 HVL | 12.5 % |
| 4 HVL | 6.25 % |
| 5 HVL | 3.125 % |
| 7 HVL | 0.78125 % |
| 10 HVL | 0.0976563 % |
| 13 HVL | 0.012207 % |
| 20 HVL | 9.537×10⁻⁵ % |
Quick answers
Quick answers
- How many HVL is 1 %?
- 1 % is 6.64386 HVL.
- How many HVL is 10 %?
- 10 % is 3.32193 HVL.
- How many HVL is 3 %?
- 3 % is 5.05889 HVL.
The units
About these units
Percent transmitted (%)
How much radiation gets through.
Half-value layers (HVL)
How many halvings the beam has been through.
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