CalcChef tool collection
Hardware Tools
Check common electronics and hardware calculations before you build, troubleshoot, or buy components.
Start with these tools
Battery Life Calculator
Battery runtime from mAh, mA and both voltages: 2,500 mAh at 3.7 V into a 500 mA, 5 V load through an 85% converter runs 3 h 9 min, not 5 h.
LED Resistor Calculator
Series resistor for one LED or a string of LEDs from supply voltage, forward voltage and current: exact ohms, the E24 value above it, power and rating.
Ohm's Law Calculator
Enter any two of voltage (V), current (A), resistance (Ω) and power (W) to solve the other two with V = IR and P = VI, shown with SI prefixes.
Voltage Drop Calculator
Voltage drop in volts and percent for copper or aluminum wire, 22 AWG to 1000 kcmil, DC, single- or three-phase, from one-way feet, amps and source volts.
All Hardware Tools
7 free browser-based tools
Battery Life Calculator
Battery runtime from mAh, mA and both voltages: 2,500 mAh at 3.7 V into a 500 mA, 5 V load through an 85% converter runs 3 h 9 min, not 5 h.
LED Resistor Calculator
Series resistor for one LED or a string of LEDs from supply voltage, forward voltage and current: exact ohms, the E24 value above it, power and rating.
Ohm's Law Calculator
Enter any two of voltage (V), current (A), resistance (Ω) and power (W) to solve the other two with V = IR and P = VI, shown with SI prefixes.
PCB Trace Width Calculator
PCB trace width from current, copper weight and temperature rise by the IPC-2221 formula, in mils and mm, plus the trace resistance and voltage drop.
Resistor Color Code Calculator
Read 4-, 5- and 6-band resistor color codes or SMD codes like 472 as ohms with tolerance, or type 4.7k to get its bands. Brown black red gold is 1 kΩ ±5%.
Server Rack Power Budget
Add up server and device watts to get the rack load in kW, its heat in BTU per hour, a branch circuit size and the monthly and yearly energy cost.
Voltage Drop Calculator
Voltage drop in volts and percent for copper or aluminum wire, 22 AWG to 1000 kcmil, DC, single- or three-phase, from one-way feet, amps and source volts.