LED Resistor Calculator

Equations

$R = (V_{supply} - V_f) / I$    $P = (V_{supply} - V_f) \times I$

Results

Enter values above and calculate.

Usage Note

Use a resistor wattage rating above the calculated dissipation. If close to a standard rating, move to the next size up. Single LED series path only.

LC Resonance Calculator

Equation

$f = \dfrac{1}{2\pi\sqrt{L \cdot C}}$

Results

Enter inductance and capacitance, then calculate.

Usage Note

Ideal resonance calculation. Real layouts, ESR, parasitics, self-resonance, and measurement fixtures all matter at RF.

Voltage Divider Calculator

Equation

$V_{out} = V_{in} \times \dfrac{R_2}{R_1 + R_2}$

Results

Enter values above and calculate.

Usage Note

Assumes an unloaded divider. Any connected load changes the effective output voltage and current.

Touchstone Import

📂

Drop .s1p / .s2p / .s3p / .s4p here

or click to browse

Smith Chart No data

|S| vs Frequency

Component Type

Inductor Parameters

Model Equations

$$ Z_L = \frac{(R_{DC} + j\omega L) \cdot \frac{1}{j\omega C_p}}{R_{DC} + j\omega L + \frac{1}{j\omega C_p}} $$ $$ f_{SRF} = \frac{1}{2\pi\sqrt{LC_p}}, \quad Q = \frac{\omega L}{R_{DC}} $$

Smith Chart — Component Impedance

Impedance |Z| (dB) vs Frequency

Phase (°) vs Frequency

Radar Range Calculator

FMCW Parameters

Results

Received Power vs Range

Radar Range Equation

$$ R_{max} = \left[\frac{P_t \cdot G_t \cdot G_r \cdot \lambda^2 \cdot \sigma}{(4\pi)^3 \cdot k T_0 B F \cdot SNR_{min}}\right]^{1/4} $$
$$ \Delta R = \frac{c}{2 B_{FMCW}}, \quad \Delta v = \frac{\lambda}{2 T_{sweep}}, \quad f_d = \frac{2v}{\lambda} $$

PCB Trace Fusing Current

Estimates the DC current at which a copper trace will fuse (melt) and the recommended operating current for a given temperature rise.

Results

Equations

$$ I_{fuse} = 0.025 \cdot W \cdot t_{cu} \cdot \sqrt{\frac{\log\left(\frac{T_{melt} - T_{amb}}{T_{ref} - T_{amb}} + 1\right)}{33 \cdot t_{pulse}}} $$
$$ I_{op} = k \cdot \Delta T^{0.44} \cdot A^{0.725} \quad \text{(IPC-2152)} $$

Lower result between IPC-2152 operating current and pulse fusing current is shown. For DC (t=0), only IPC-2152 applies.

Bandwidth & Max Conductor Length

Determine the maximum trace length before transmission-line effects matter, and the bandwidth limit for a given trace length.

Results

Equations

$$ L_{max} = \frac{c \cdot \text{frac}}{f \cdot \sqrt{\varepsilon_{eff}}}, \quad BW = \frac{0.35}{t_r}, \quad \lambda = \frac{c}{f \cdot \sqrt{\varepsilon_{eff}}} $$
$$ \varepsilon_{eff} \approx \frac{\varepsilon_r + 1}{2} + \frac{\varepsilon_r - 1}{2} \left(1 + 12\frac{h}{w}\right)^{-0.5} $$

When trace length exceeds λ/frac, distributed transmission-line effects become significant.

Conductor DC Properties

DC resistance, inductance, and capacitance per unit length for a PCB trace.

Results

Equations

$$ R_{DC} = \frac{\rho \cdot L}{W \cdot t}, \quad L_{self} \approx 0.00508 \cdot L \cdot \left(\ln\frac{2L}{W+t} + 0.5 + 0.2235\frac{W+t}{L}\right) $$

Copper resistivity: 1.724e-6 Ω·cm at 20°C, temp coefficient 0.00393 /°C.

PA Hold-Up Capacitor

Verify with actual cap value

Results

Droop vs Capacitance

Design Equations

$$ C_{required} = \frac{I \cdot t}{\Delta V - \Delta V_{ESR}}, \quad \Delta V_{ESR} = I \cdot R_{ESR} $$ $$ \Delta V_{total} = \frac{I \cdot t}{C} + I \cdot R_{ESR}, \quad \text{Droop\%} = \frac{\Delta V_{total}}{V_{supply}} \times 100 $$

Decoupling Goal

Cap Banks

BankQtyC (μF)ESR (mΩ)ESL (nH)
HF
MF
Bulk

First-pass PDN shaping only: identical parts are paralleled, then combined with a simple shared mount ESL + rail resistance. It is meant to show where each bank helps and where anti-resonance starts to hurt.

What this tab is showing

Quick Read

|Z| vs Frequency

Bank Coverage Map

Each bar is centered on that bank’s self-resonant frequency. Long bars mean lower-frequency coverage. Short bars mean the bank mainly helps near the fast edge.

Bank Details

BankTotal CEq ESREq ESLSRFUse it for

Cascade System Setup

Stage Chain

Stage NameGain (dB) NF (dB)IIP3 (dBm)

Cascade Results

#StageGain (dB)NF (dB)IIP3 (dBm) Cum. Gain (dB)Signal Out (dBm)Noise Out (dBm)SNR (dB)

Cascaded NF — Friis Formula

$$ F_{total} = F_1 + \frac{F_2 - 1}{G_1} + \frac{F_3 - 1}{G_1 G_2} + \cdots $$ $$ \frac{1}{IIP3_{total}} = \frac{1}{IIP3_1} + \frac{G_1}{IIP3_2} + \frac{G_1 G_2}{IIP3_3} + \cdots $$

Power: dBm ↔ Watts ↔ mW

⇄
⇄
$P_{dBm} = 10\log_{10}(P_{mW}), \quad P_{mW} = 10^{P_{dBm}/10}$

dB ↔ Linear Ratio

⇄
⇄
$dB = 20\log_{10}(V_{ratio}) = 10\log_{10}(P_{ratio})$

Frequency ↔ Wavelength

⇒
$\lambda = c/f, \quad c = 3 \times 10^8$ m/s

Impedance — Z ↔ Γ ↔ VSWR

⇒
$\Gamma = (Z-Z_0)/(Z+Z_0), \quad VSWR = (1+|\Gamma|)/(1-|\Gamma|), \quad RL = -20\log_{10}|\Gamma|$

Noise Temperature ↔ Noise Figure

⇄
$T_e = T_0(F-1), \quad T_0 = 290$ K, $\quad F = 10^{NF_{dB}/10}$

Ohm's Law + Power

Leave exactly one field blank, then click solve.

Results

RC Cutoff + Time Constant

Results

dBm ↔ Voltage (Vrms / Vpp)

Results

Planar Spiral Inductor

Estimate inductance of a square planar spiral inductor on a PCB. Uses the Modified Wheeler formula.

Results

Equations

$$ L = K_1 \cdot \mu_0 \cdot n^2 \cdot \frac{d_{avg}}{1 + K_2 \cdot \rho} $$

Modified Wheeler formula (Mohan et al.). d_avg = (D_out + D_in)/2, rho = (D_out - D_in)/(D_out + D_in). K1=2.34, K2=2.75 for square.

Crystal Oscillator Load Capacitance

Calculate load capacitors for a crystal oscillator. C1 and C2 are the external load caps on each pin.

Results

Equations

$$ C_1 = C_2 = 2 \cdot (C_L - C_{stray}), \quad f_{err} = \frac{C_L - C_{load}}{2 \cdot C_1} \cdot 10^6 $$

Assumes C1 = C2. PPM error from incorrect loading: ppm = (CL_nom - CL_actual) / (2*C1) * 1e6.

Wire Gauge & Drill Chart

American Wire Gauge (AWG) lookup with diameter, resistance, and current capacity. Standard PCB drill bit sizes.

Results

Common PCB Drill Sizes

Embedded Resistor Calculator

Calculate resistor dimensions for embedded PCB resistor materials (Ohmega, Ticer, etc.). Sheet resistance in ohms-per-square.

R = R_sheet * L / W. L = R * W / R_sheet. Enter width + either target R or length.

Results

Equation

$$ R = R_{\square} \cdot \frac{L}{W}, \quad \text{Squares} = \frac{L}{W} $$

4-20mA Sensor Input / Output

Convert between 4-20mA loop current and engineering units (pressure, temperature, level, flow, etc.). Also compute loop resistance, supply requirements, and receive resistor sizing.

 units
 units

Loop Power & Receive Resistor

Results

Reference — Standard 4-20mA Ranges

Sensor TypeTypical Range
Pressure0-100 PSI, 0-5000 PSI, -15-50 PSI
Temperature-40 to 85°C, 0-200°C, 0-600°C
Level0-10 ft, 0-100 in, 0-50 m
Flow0-10 GPM, 0-1000 SCFH
Flame Intensity0-100%, 0-5 UV counts
Speed / RPM0-3600 RPM, 0-10000 RPM
Current% of SpanApplication
3.6-3.9 mA< 0%Sensor fault / under-range
4.0 mA0%Live zero (sensor OK)
8.0 mA25% 
12.0 mA50%Mid-scale
16.0 mA75% 
20.0 mA100%Full scale
> 21 mA> 105%Sensor fault / over-range

Equations

$$ \text{Value} = \left(\frac{I - 4\,\text{mA}}{16\,\text{mA}}\right) \times (\text{Range}_{max} - \text{Range}_{min}) + \text{Range}_{min} $$
$$ I = 4\,\text{mA} + \left(\frac{\text{Value} - \text{Range}_{min}}{\text{Range}_{max} - \text{Range}_{min}}\right) \times 16\,\text{mA} $$
$$ R_{loop\,max} = \frac{V_{supply} - V_{sensor}}{20\,\text{mA}}, \quad V_{recv} = I \times R_{recv} $$

PCB Trace Temperature Rise

Estimate trace temperature rise from DC current using IPC-2152 approximations. Internal traces run hotter than external for the same current.

Results

Equations & Notes

$$ \Delta T = \left(\frac{I}{k \cdot A^{0.725}}\right)^{1/0.44} \quad R(T) = R_{25} \cdot (1 + 0.00393 \cdot \Delta T) $$

k = 0.048 (external) or 0.024 (internal). A = cross-section in (mil²)/1000. IPC-2152 approximation. For precise thermal simulation, use finite-element tools.

About Copper Trace Works

Practical tools first. Products when they are worth shipping.

Copper Trace Works LLC is a small Alabama-based maker business focused on practical calculator tools, hobby electronics, display kits, bench gadgets, 3D-printed accessories, and engineering-minded product ideas.

Business Profile

Legal entityCopper Trace Works LLC
Primary audienceEngineers, hobbyists, and makers
PlatformStatic website on Cloudflare Pages
CommerceShopify on a separate subdomain

Operating Position

Products and tools are intended for hobbyist, educational, and experimental use unless otherwise stated. Not for medical, life-safety, aviation, automotive safety-critical, or other mission-critical applications unless explicitly certified for that use.

Contact

For product questions, calculator corrections, or documentation requests:

support@coppertraceworks.com

shop.coppertraceworks.com

© 2026 Copper Trace Works LLC

Via Properties (first-order)

Calculated Values

PropertyValueUnits

Ampacity estimate uses conservative current-density guidance for via barrel copper. Validate against board stack-up and thermal reality.

Minimum Copper Spacing (IPC quick table)

Spacing Table Stack

Voltage bandBase spacing (mil)Adjusted (mil)Adjusted (mm)

Differential Pair + Crosstalk (first-order)

Results

MetricValue

Trace Impedance Planner

Pick the transmission-line picture first, then tune width, gap, copper, and dielectric values for a fast first-pass impedance estimate before you hand the stack to your fab or field solver.

Choose line family
Wheeler / Wadell is the more accurate first-pass option for microstrip-family geometry. Stripline modes use the stripline closed-form regardless of this selector.

Calculated stack snapshot

Outer-layer microstrip over a single reference plane.

Equation set: Wheeler / Wadell — more accurate first-pass microstrip estimate.

Target check pending
Current impedance
—
current width
Recommended W1
—
for target Z₀
Finished width W2
—
after etch
Delay
—
ps / in
Capacitance
—
pF / in
Inductance
—
nH / in

Stack cross-section

Altium-inspired layer picture with W1/W2 and dielectric callouts
Microstrip

Width sweep

Sweep around the current width so you can see where the target sits and how hard the line moves with geometry changes.

Target band pending Structure pending

Width sweep table

W1 (mil)W2 (mil)Z₀ (Ω)Error vs targetDelay (ps/in)

What matters most