Technology
Technology: 28 free calculators & tools, including Resistor color code calculator and Data storage units. Explore formulas, examples and visual explanations.
Electronics
Resistor color code calculator
Read 4-, 5- or 6-band resistors, or turn a resistance value into colors, with tolerance and temperature coefficient.
DC cable voltage drop
Estimate cable voltage loss, resistance and the conductor area needed for a chosen drop target.
555 timer calculator
Calculate astable frequency and duty cycle or a monostable pulse, with component-tolerance bounds.
Ohm’s law and LED resistors
Solve low-voltage DC resistance, current and power, or size an ideal LED series resistor.
Voltage divider calculator
Find output voltage or the lower resistor, including an optional resistive load.
Series and parallel components
Combine up to twelve resistors or capacitors and compare series and parallel equivalents.
RC charging and discharging
Explore capacitor voltage over time, time to a target voltage and the RC time constant.
3D printing
3D-print layer and color-change planner
Convert a desired pause height into a completed layer and compare rounding methods.
Filament length and weight
Convert meters and grams using filament diameter and your material’s density.
3D printing volumetric flow
Compare required extrusion flow with a tested limit, or calculate the speed at that limit.
3D print dimension correction
Calculate separate X, Y and Z scale adjustments from intended and measured dimensions.
Photo, video & audio
Video file size
Estimate video storage from bitrate and duration, or solve bitrate for a size limit.
Image print size and resolution
Compare print dimensions and resolution, preserving aspect ratio for fit or crop.
Room modes and acoustics
Explore rectangular-room resonances and an ideal mode’s pressure pattern.
Photography depth of field
Find near and far focus limits and hyperfocal distance from your lens and viewing criterion.
Time-lapse planner
Plan frame count and playback duration, or solve the interval for a target video length.
Music tempo and delay
Calculate straight, dotted and triplet note timings plus bar and loop duration.
ND-filter exposure
Convert filter stops or optical density into an exposure time, including two stacked filters.
Screen viewing distance and angle
Find the viewing angle or seating distance for a monitor, TV or projector screen, using its diagonal and aspect ratio.
Color converter
Convert opaque colors between HEX, RGB, HSL, HSV and approximate CMYK, with a live swatch and color picker.
Image compressor
Reduce image file size, adjust quality and resize photos in your browser. Compare the result and download it without uploading your image.
Image converter and resizer
Convert JPEG, PNG and WebP, set pixel dimensions and download your image without uploading it.
Web & digital tools
Data storage units
Convert decimal and binary storage units with explicit bit and byte distinctions.
Download and transfer time
Estimate transfer time from file size, link speed and your assumed efficiency.
Screen pixel density
Estimate pixels per inch and physical screen dimensions from native resolution and display diagonal.
QR code generator
Create free QR codes for links, text, Wi-Fi, email, phone and contacts. Add colors, a logo or frame and download PNG or SVG, entirely in your browser.
Barcode generator
Create linear barcodes, Data Matrix, PDF417 and Aztec codes with validated inputs and PNG or SVG exports.
Favicon generator
Turn your image into a favicon pack with ICO, PNG icons, a web manifest and installation tags. Generate and download everything locally, for free.