🧮 Calculators
Free interactive tools to help you spec your electronics projects.
LED current-limiting resistor calculator
Given supply voltage, LED forward voltage and forward current, computes the ideal series resistor, nearest E12/E24 standard values, power dissipated and the minimum resistor power rating.
Open calculatorResistor colour-code decoder
Pick the colour bands (4 or 5 band) and read off the resistance, tolerance and the value range. Shows a live visual band strip.
Open calculatorVoltage divider calculator
Enter Vin, R1 and R2 and get Vout across R2, the divider current and the power dissipated, with a warning for power-hungry divider ratios.
Open calculatorNeopixel / WS2812 power budget
Estimate current and wattage for an addressable LED strip from pixel count, brightness and colour mix; recommends a PSU size (worst case + headroom) and flags when to inject power at both ends.
Open calculatorPCB trace width calculator (IPC-2221)
IPC-2221 trace-width estimate from current, allowed temperature rise, copper weight and trace location (external/internal). Outputs width in mm and mils plus cross-sectional area.
Open calculatorCapacitor code decoder
Pick the digits printed on your ceramic or MLCC capacitor and the tolerance letter — the code decodes live into pF, nF, and µF. An SVG disc cap shows the code on its face and updates as you change the digits.
Open calculatorRC time constant & filter cutoff calculator
Drag R and C to see the exponential charge or decay curve animate in real time. Shows time constant τ, cutoff frequency fc, and settle time — for low-pass and high-pass RC filters.
Open calculatorResistor series & parallel calculator
Choose series or parallel, pick 2–4 resistors, drag each log-scale slider — watch the SVG circuit redraw and the total resistance update instantly. Shows the formula, the minimum resistor in parallel, and the sum for series.
Open calculatorSMD resistor code decoder
Decode any SMD resistor marking — 3-digit, 4-digit, or EIA-96 — and read the resistance live. Tap digits or use the slider; the chip face updates in real time.
Open calculatorBattery life estimator
Pick a battery chemistry, set the active and sleep current plus duty cycle, and watch the SVG battery fill and square-wave waveform update live. Shows runtime in the friendliest unit — hours, days or years.
Open calculatorWire gauge (AWG) calculator
Drag current, length, and allowed voltage drop — watch the wire cross-section fatten in real time. Finds the smallest AWG that keeps your drop within budget, then shows resistance, actual drop, and power loss.
Open calculatorI²C pull-up resistor calculator
Choose your Vcc, bus speed, and total bus capacitance, then watch the I²C bus diagram update live — including the RC rising-edge waveform that sharpens with stronger pull-ups and softens with more capacitance. Calculates the minimum and maximum pull-up values per the I²C specification.
Open calculatorServo pulse-width to angle calculator
Drag the pulse-width slider and watch a servo arm rotate live. Choose Standard (1000–2000 µs) or Extended (500–2500 µs) calibration and see the exact angle, µs per degree, and the 20 ms refresh cycle at a glance.
Open calculatordBm ↔ milliwatt (RF power) converter
Drag the dBm slider and watch a logarithmic power meter fill and colour-shift in real time. Shows milliwatt, watt, and relative gain vs 1 mW. Reference chips snap to common LoRa / ISM transmit levels.
Open calculatorRGB / HEX / NeoPixel colour converter
Pick any RGB colour with three sliders or a preset chip, then instantly see the HEX code, HSV values, and the exact byte sequence your NeoPixel strip expects — switch between GRB, RGB, and GRBW byte orders.
Open calculatorBattery pack configurator (series/parallel)
Choose a cell chemistry, set capacity and the S×P configuration, and watch a live grid of battery-cell icons redraw. Shows pack voltage, capacity, energy and max charge voltage instantly.
Open calculatorInductor colour-code decoder
Decode 4-band colour-coded inductors: tap each colour band on the live inductor diagram and instantly read the inductance in µH, mH or H, the tolerance, and the guaranteed range.
Open calculatorLinear regulator heat calculator
Drag the input voltage and load current, pick an output voltage and heatsink option — watch the TO-220 package glow red-hot as heat builds up. Shows power dissipated, efficiency, and junction temperature with thermal shutdown warnings.
Open calculatorPWM to analog voltage calculator
Drag the duty cycle and pick a supply voltage to see the average analog output voltage update live. Shows the equivalent Arduino analogWrite value, PWM frequency context, and a live square-wave visualisation with a dashed average-voltage line.
Open calculatorStepper motor steps/mm calculator
Pick belt or leadscrew drive, set step angle and microstepping, then watch a live SVG of the motor and mechanism update. Outputs steps/mm for Marlin M92 or GRBL $100–$102 firmware config.
Open calculatorADC resolution & step size calculator
Pick bit depth and Vref to see how coarse or fine the quantised staircase is vs the true analog signal. Shows step size (LSB) in the nicest unit, number of levels, ideal SNR, and a worked count-to-voltage example.
Open calculatorNTC thermistor temperature calculator
Enter a measured resistance and instantly read the temperature (or vice-versa) using the Beta/B-parameter equation. Pick the nominal resistance (10 kΩ or 100 kΩ) and Beta coefficient, then drag the slider and watch the SVG thermometer fill in real time.
Open calculator3D printer filament cost calculator
Choose your filament material and diameter, set the print mass and spool price, and watch the animated spool empty as your slice consumes it. Shows filament cost, length used, and what fraction of a 1 kg spool the print burns through.
Open calculatorLC resonant frequency calculator
Drag L and C to see the resonance peak animate in real time. Shows resonant frequency, reactance at resonance, Q factor, and bandwidth — for LC tank circuits, oscillators, and radio tuning.
Open calculatorAntenna length calculator
Pick a common ISM band or drag the frequency slider and instantly see the quarter-wave whip or half-wave dipole length in mm, drawn to scale. Adjust the velocity factor for coated or loaded wire.
Open calculatorGPIO current budget calculator
Choose your board, dial in how many GPIO pins you are driving and at what current, and watch the chip diagram light up while a budget bar shows headroom to the chip's total GPIO limit. Flags per-pin and total violations instantly.
Open calculatorLogic level shifter selector
Pick your From and To voltages and signal type (bidirectional I²C/one-wire or unidirectional push-pull), and watch the circuit diagram update live — the shifter block recolours and relabels to show the right technique, voltage bars scale to each domain, and the arrow flips between one-way and two-way.
Open calculatorBuck / boost converter current calculator
Set your input voltage, output voltage, load current, and efficiency — watch the power bars react and see how a boost converter pulls MORE input current than it delivers (Pin = Pout / η). Essential for sizing wiring and your supply.
Open calculatorSample rate & Nyquist calculator
Set the signal frequency and sample rate to see sample dots on the sine wave. When the sample rate drops below 2x the signal frequency, a red alias sine appears — the false lower frequency the ADC actually reconstructs. Shows Nyquist frequency, samples per cycle, and alias frequency.
Open calculatorPCB trace impedance calculator
Drag trace width and dielectric height, pick copper weight and material, and watch the PCB cross-section update live. Calculates characteristic impedance (Z₀) for microstrip or stripline using IPC-2141 approximations, with the nearest common target (50/75/90/100 Ω).
Open calculatorPCB via current capacity calculator
Pick a via diameter, plating weight, allowed temperature rise and number of vias — watch the annular copper ring thicken and the array expand in real time. IPC-2221 barrel current from drill diameter, plating thickness and ΔT, plus a per-array total.
Open calculatorPower supply sizing calculator
Tap device presets to build your load list, set your system voltage and headroom, and watch the current bar fill live — showing where your total draw sits against the recommended supply rating. Rounds up to a sensible adapter current and shows required wattage.
Open calculatorUART baud rate error calculator
Pick your MCU clock, target baud rate, and oversample mode, then watch the error gauge needle swing — green when within ±2%, red when the timing is too far off for reliable comms. Calculates the AVR-style UBRR divisor and shows actual baud vs target.
Open calculatorTimer prescaler & period calculator
Pick a CPU clock and a target interrupt frequency then watch the SVG signal-chain update — chosen prescaler divisor, TOP/ARR register value, actual achieved frequency, and error % vs target all update live.
Open calculatorWireless range & link budget calculator
Pick a radio mode (LoRa SF12 to WiFi), drag Tx power and antenna gain sliders, select a frequency band, and watch the two-node SVG range arc grow or shrink in real time. Shows line-of-sight distance, link budget (MAPL), data rate, and Rx sensitivity.
Open calculatorCAN bus bit timing calculator
Pick a CAN clock and target bit rate, watch the bit-time diagram redraw — SYNC, TSEG1 and TSEG2 blocks resize proportionally, the sample-point marker moves, and BRP, register values, SJW and achieved bit rate all update live.
Open calculatorRL inductor time constant calculator
Drag L and R to see the exponential current-rise curve animate in real time. Shows time constant τ = L/R, settle time, RL corner frequency, and stored energy — with a flyback warning for relay/solenoid drivers.
Open calculatorSolar panel sizing calculator
Set your average load, location sun hours, and autonomy days — watch an SVG scene animate the sun intensity, panel size, and battery fill live. Calculates required panel wattage and battery capacity (Ah).
Open calculatorServo & motor torque converter
Enter a torque value in any common servo/motor datasheet unit (kg·cm, oz·in, N·m, g·cm) and instantly see all equivalents. The live SVG lever shows how far from the pivot you can hold a given weight — making abstract torque numbers tangible.
Open calculatorLED matrix refresh rate calculator
Set your matrix panel size, scan rate, colour depth and pixel clock to see the computed refresh rate and a live animated LED grid that highlights the active scan line sweeping down the panel. A flicker badge and colour tally show whether your settings are camera-friendly.
Open calculatorSD card write endurance calculator
Choose flash type and card size, dial in your logging rate, and watch the microSD card colour shift from green to red as projected lifetime shortens. Shows write-endurance lifetime in years with total writable data and daily write volume.
Open calculatorEEPROM / flash write endurance calculator
Select your memory technology, dial in how often you write and how many locations you spread writes across, and watch the memory cell grid shift from healthy green to critical red as projected lifetime shortens. Flags the classic AVR EEPROM gotcha: writing every minute wears it out in under 70 days.
Open calculatorEnclosure ventilation calculator
Set the heat dissipated inside and the allowed temperature rise — watch a fan spin faster or vent slots grow to match. Calculates the required airflow in CFM, L/s, and m³/h, suggests a fan size, and flags when natural convection won't cut it.
Open calculatorDrill & tap size for screws
Pick a metric or imperial screw size and hole type — clearance, tapped (metal), or self-tapping (plastic/3D print) — and see the recommended drill diameter in mm and inches, with a live cross-section SVG that scales the hole relative to the screw shank.
Open calculatorPCB standoff & stack height calculator
Dial in board count, thickness, tallest component and safety margin, then watch a live side-view of the stack redraw. Recommends the nearest standard standoff length and shows total assembled height.
Open calculatorStepper driver Vref current calculator (A4988 / DRV8825 / TMC)
Set the driver type and desired motor coil current — the calculator shows the exact Vref voltage to dial in on the tiny trim-pot. Watch the SVG multimeter reading and pot indicator update live. Covers A4988, DRV8825, and TMC2209 with board-specific Rsense options.
Open calculatorArduino millis() / micros() rollover calculator
See exactly when millis() or micros() wraps to zero — a live ring fills as uptime climbs toward the 2^32 rollover. Learn why unsigned subtraction is safe and `millis() >= target` is not.
Open calculatoranalogRead to voltage calculator
Pick your board, drag the raw ADC count, and watch a vertical voltage gauge fill in real time. Shows the computed voltage, LSB step size, max count, and board-specific tips (including the ESP32 non-linearity warning and the Raspberry Pi no-ADC notice).
Open calculatorArduino sketch memory (will it fit?) calculator
Pick a board, drag the sketch size and variable usage sliders, and watch two filling bars show Flash and SRAM usage — turning green, amber, or red — while a live verdict tells you whether your sketch will fit and flags the sneaky SRAM limit before your program crashes at runtime.
Open calculatorUSB & board power budget calculator
Pick your USB power source and board, drag the peripherals slider, and watch the SVG cable and gauge react live — instantly showing whether your port can actually deliver enough current to boot and run your board without brown-outs.
Open calculatorHC-SR04 ultrasonic distance calculator
Enter an echo-pulse time (or a target distance) and instantly see the measured distance — with temperature-corrected speed of sound. Watch an animated sonar pulse travel from the sensor to the target and back.
Open calculatorHX711 load cell calibration calculator
Pick your load cell capacity and sensitivity, choose HX711 gain (128 or 64), then drag the current-load slider to see the live raw count and digital readout. Gives the set_scale() calibration factor, full-scale bridge voltage, and usable resolution.
Open calculatorStepper motor speed calculator (RPM vs step rate)
Set your motor's step angle, microstepping, and target RPM (or step rate) to instantly get the pulse frequency your driver needs. Includes a live SVG of the motor shaft spinning at the chosen speed.
Open calculatorSPI clock speed calculator
Pick your board clock and either a fixed divider or a target max SCK speed — the animated SPI bus shows the actual SCK frequency, which divider is used, and maximum byte throughput.
Open calculatorArduino map() & sensor calibration calculator
Set your two calibration points (raw input range → output range), drag the current reading, and see the mapped value live. Draws the calibration line in real time, shows the exact map() call, slope, and highlights integer vs float precision.
Open calculatorNeoPixel refresh rate & max LEDs calculator
Set your LED type, strip length and target frame rate to see exactly how fast your NeoPixels can refresh. The WS2812 protocol runs at a fixed 800 kHz — drag the pixel count to watch FPS drop in real time, or flip to target-FPS mode to find the maximum strip length. Animated LED chase updates at the computed rate.
Open calculatorDisplay framebuffer RAM calculator
Pick a display preset and a board, then watch the SRAM bar fill with the framebuffer size — turning red when the buffer is bigger than the chip's free RAM. Instantly see whether your chosen MCU can hold a full frame in memory, or whether you need to draw directly to the panel.
Open calculatorCrystal load capacitor calculator
Pick your crystal's load capacitance and stray capacitance — watch the schematic update live with the computed C1/C2 values and nearest standard cap. Covers 32.768 kHz RTC crystals through fast MCU clocks.
Open calculatorESP32 PWM (LEDC) resolution calculator
See exactly how the ESP32 LEDC peripheral trades PWM frequency against duty resolution. Pick a clock source and either drag a target frequency (to see the max usable resolution) or a bit depth (to see the max frequency). The SVG shows the PWM waveform with a staircase overlay whose step count reflects available duty levels — coarse at high frequency, smooth at low.
Open calculatorI²C address calculator & reference
Decode 7-bit I²C addresses to write/read bytes, or reverse 8-bit datasheet bytes back to 7-bit — with a live 128-cell address map that highlights reserved ranges and common device addresses. Includes quick-pick presets for popular sensors and modules.
Open calculatorCoin cell battery life calculator (deep sleep)
Pick a coin-cell type, set active current, wake time, wake interval and sleep current, and watch the SVG coin-cell fill drain and the pulse waveform update live. Flags brownout risk when active current exceeds the cell's pulse rating. Shows runtime in the friendliest unit — days, months or years — capped at the 10-year shelf life.
Open calculatorSwitch debounce calculator (RC & software)
Drag the bounce duration or pick R and C values to see a bouncy raw switch signal cleaned into a stable debounced output — live on a timeline. Covers both the software delay and hardware RC + Schmitt-trigger approaches.
Open calculatorConductive thread resistance & voltage drop calculator
Pick your thread type and drag run length and current — watch the stitched line fade from battery to LED as voltage is consumed, and see the LED dim when the drop is too large. Essential for LilyPad and wearable projects where thread resistance kills brightness.
Open calculatorMPU-6050 IMU range & tilt calculator
Choose accelerometer and gyroscope full-scale ranges, drag the pitch slider, and watch the MPU-6050 breakout board tilt live. Instantly see LSB sensitivity, resolution, and the raw axis counts — including when the range clips.
Open calculator