Compute TVL from measurements or material data today. Solve thickness for any required transmission level. Export results for reports, audits, and design reviews easily.
The tenth value layer (TVL) is the thickness of a shielding material that reduces transmitted intensity to one-tenth of its incident value.
| TVL (cm) | Thickness x (cm) | Computed Transmission T | Transmission (%) | Notes |
|---|---|---|---|---|
| 0.50 | 0.50 | 0.10 | 10 | One TVL reduces intensity to one-tenth. |
| 0.50 | 1.00 | 0.01 | 1 | Two TVLs reduce intensity by 100×. |
| 1.20 | 2.40 | 0.01 | 1 | Thickness equals two TVLs for 1% transmission. |
| 2.00 | 3.00 | 0.0316 | 3.16 | Fractional TVLs are valid for estimates. |
Real shielding performance depends on energy spectrum, buildup, geometry, and material composition.
A tenth value layer (TVL) is the material thickness that reduces transmitted intensity to 10% of the incident intensity. In practical terms, each added TVL multiplies transmission by 0.1, so two TVLs give 1% and three TVLs give 0.1%. This log-based behavior makes TVL convenient for quick design estimates.
Shielding targets are often expressed as a permitted fraction of unshielded intensity. For example, a target transmission of 0.05 means 5% of the original beam passes through. Using x = −TVL·log₁₀(T), a 5% goal requires about 1.301 TVLs of thickness because log₁₀(0.05) ≈ −1.301.
HVL reduces intensity to 50%, while TVL reduces to 10%. They are linked by TVL ≈ 3.32193·HVL and HVL ≈ 0.30103·TVL. If a datasheet reports HVL = 0.30 cm, the matching TVL is about 0.9966 cm. These conversions help when only one layer metric is published.
TVL is not a universal constant; it depends on photon energy, material composition, and the radiation spectrum. Higher energies typically increase TVL, meaning thicker shielding is required for the same reduction. Dense materials (lead, tungsten, concrete mixtures) often provide lower TVL values than low-density materials for comparable energies.
Many projects use fractional TVLs rather than whole layers. For instance, 0.75 TVL corresponds to T = 10−0.75 ≈ 0.1778 (17.78%). This calculator supports fractional thicknesses and outputs both ratio and percent, which is useful for iterative design and cost optimization.
If you can measure transmission through a known thickness, you can estimate TVL using TVL = −x / log₁₀(T). For example, if 2.5 cm of shielding yields T = 0.02, then TVL ≈ 2.5 / 1.699 ≈ 1.471 cm. Repeat measurements at consistent geometry to improve confidence.
Professional reports usually include the chosen target (T), the input TVL or HVL source, the computed thickness, and units. Exporting CSV supports spreadsheets and QA logs, while PDF supports attachments for design reviews. Capture the mode used so reviewers can reproduce the calculation exactly.
TVL models the primary attenuation trend but real installations may need additional allowance for buildup, scatter, field size, and gaps. Use this calculator for planning and comparison, then verify with applicable standards, measured dose rates, and site-specific geometry before final approval.
HVL halves intensity (50%), while TVL reduces it to one-tenth (10%). They are related by TVL ≈ 3.32193·HVL, which allows conversion when only one value is available.
0.1% is 0.001 as a ratio. Because transmission scales as 10−x/TVL, you need 3 TVLs to reach 10−3 = 0.001.
TVL is mainly used for photon shielding (X-rays and gamma rays). For neutrons or charged particles, different attenuation models and materials are required, so use appropriate radiation-specific methods.
The physics is unchanged; only the displayed unit changes. The calculator converts inputs internally to a common scale, then converts the output back to your selected unit for reporting.
Yes. The equations are logarithmic and continuous, so partial layers are meaningful. Fractional TVLs are common in optimization studies where thickness, weight, and cost must be balanced.
Measure transmission T through a known thickness x under consistent geometry. Then compute TVL = −x / log₁₀(T). Repeat and average results to reduce measurement uncertainty.
Often, yes. Real setups include scatter, buildup, gaps, and construction tolerances. Use the computed value as a baseline, then apply your project’s safety factor and verification measurements before finalizing shielding.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.