Engineering Toolbox

Yubal Torres

In-app purchases

About this app

Engineering Toolbox is a lightweight set of electronics and engineering tools that applies the formulas for you, so you don't have to remember them. Type what you know and get the answer, the formula and the nearest standard part: resistor color codes, capacitor codes, LED resistors, parallel resistors, unit conversions and more.

Made for students, makers, technicians and electricians.

Free, no ads, no account
• 14 calculators that stay free
• History, saved setups, favorites and search
• Works offline, in light or dark theme, in English and Spanish

DC circuits
• Ohm's law: voltage, current, resistance and power
• LED resistor: the right resistor, its color bands and wattage
• Voltage divider: Vout, or R1 and R2 as standard values
• Parallel resistors
• Wheatstone bridge

AC and filters
• RC and RL circuits: cutoff frequency and charge time
• Capacitive and inductive reactance
• Transformer: turns, voltage and current

Components
• Resistor colors: 4, 5 and 6 bands, from colors to value and back
• Capacitor code: reads codes like 104 (100 nF), with tolerance

Digital
• Number base converter: binary, octal, decimal and hex

Math and units
• Unit converter: length, area, volume, mass, temperature, pressure, energy, power, torque, flow and speed

Pro: one purchase, no subscription
• 7 more calculators: op-amp gain, 555 timer, wire gauge and voltage drop, SMD resistor code, battery life, adjustable regulator (LM317) and decibels
• 4 home screen widgets: favorites, resistor color code, recent results and saved setups
• Unlimited history and saved setups (free keeps 20 results and 3 setups)
• More resistor series: E6, E24, E48 and E96 (free uses E12)
• Pro calculators added in later updates are included
Every calculator that's free today stays free.

Privacy
• No account, no tracking
• Your history and saved setups stay on your device

Questions or ideas? Settings → Contact support.

What’s new

Engineering Toolbox is back, rebuilt from the ground up.
• New design: light and dark themes, search, favorites and category filters
• History and saved setups: reopen any calculation with its values
• New free tools: Voltage divider and Unit converter
• Fixed: transformer current, LED resistor rounding, capacitor codes 106 and 107
• Pro, one purchase: 7 new calculators, home screen widgets, unlimited history and more resistor series