Calculator Inputs
Choose a preset or enter custom film values. Presets are representative starting points.
Example Data Table
These rows show typical workflows. Values are illustrative and should be replaced with measured process data.
| Material | Resistivity | Thickness | Length | Width | Sheet Resistance | Trace Resistance |
|---|---|---|---|---|---|---|
| Copper | 1.68 µΩ·cm | 35 µm | 50 mm | 2 mm | 0.00048 Ω/sq | 0.012 Ω |
| Aluminum | 2.82 µΩ·cm | 25 µm | 80 mm | 4 mm | 0.001128 Ω/sq | 0.02256 Ω |
| Nichrome | 108 µΩ·cm | 0.5 µm | 30 mm | 1 mm | 2.16 Ω/sq | 64.8 Ω |
| ITO Film | 1500 µΩ·cm | 150 nm | 20 mm | 10 mm | 100 Ω/sq | 200 Ω |
Formula Used
Temperature-adjusted resistivity
ρT = ρref × [1 + α × (T - Tref)]
Sheet resistance
Rs = ρT / t
Number of squares
N = L / W
Total trace resistance
R = Rs × N = Rs × (L / W)
Electrical loading
V = I × R, P = I² × R, J = I / (W × t)
Sheet resistance is measured in ohms per square. A square shape keeps the same sheet resistance regardless of its absolute size, provided thickness and material remain uniform. The calculator uses a linear resistivity-temperature model, which is practical for quick engineering estimates.
How to Use This Calculator
- Select a preset material or keep the form on custom values.
- Enter resistivity at the chosen reference temperature.
- Input film thickness and the conductor geometry length and width.
- Add the operating current to estimate voltage drop and power loss.
- Enter the temperature coefficient and both temperatures for correction.
- Press the calculate button. Results will appear above the form.
- Review the table, result cards, and Plotly graph for design behavior.
- Use the CSV or PDF buttons to export your current calculation set.
FAQs
1) What is sheet resistance?
Sheet resistance expresses the resistance of a thin film in ohms per square. It simplifies analysis of uniform layers because geometry enters mainly through the number of squares, not the absolute square size.
2) Why does thickness matter so much?
Sheet resistance is inversely proportional to thickness. When thickness decreases, the same material becomes more resistive per square. Very thin deposited films can therefore show much higher resistance than bulk conductors.
3) What does ohms per square mean?
It means the resistance measured across opposite sides of any square section of a uniform film. One square, ten squares, or half a square all scale directly with geometry through the length-to-width ratio.
4) Why is temperature included?
Resistivity changes with temperature. Many metals become more resistive as temperature rises, increasing sheet resistance, voltage drop, and heating. This calculator applies a linear temperature coefficient for fast estimation.
5) Can this be used for PCB traces?
Yes. It is useful for thin conductive paths such as PCB copper, metal films, sputtered layers, transparent electrodes, and heater strips. For high-frequency or skin-effect cases, use a more specialized model.
6) What is the number of squares?
The number of squares equals length divided by width. A 50 mm path with 2 mm width contains 25 squares. Total resistance is simply sheet resistance multiplied by that square count.
7) How accurate are the material presets?
They are convenient representative defaults only. Actual resistivity can vary with alloy, deposition process, annealing, grain structure, purity, and temperature range. Replace presets with measured values whenever possible.
8) Why export to CSV or PDF?
Exports help with design reviews, calculation logs, validation packs, and project documentation. CSV supports spreadsheet work, while PDF is useful for sharing calculation snapshots with teams or clients.