Printable shop sheets, checked against the standard
Tap drill, drill size, torque, spanner, wire and motor charts — one sheet each, sized for A4 and US Letter, with an Excel download. Every number is computed from the published standard and every sheet carries a QR code back to its page. Free, no sign-up, no watermark.
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Printable charts
Print one, pin it above the machine and stop looking it up. Each has an Excel version with every table on its own tab.
Tap Drill ChartEvery common metric, UNC and UNF thread with its tap drill and clearance hole. The one for the wall above the drill press.Drill Size ChartAll 163 number, letter and fractional drills in one ascending run, with decimal inch, millimetres and the tap each one drills for.Bolt Torque ChartTightening torque for metric property classes and SAE grades, with the multiplier for oiled and anti-seize threads.Spanner & Allen Key ChartFor each bolt: the spanner or socket, the Allen key for its cap screw, the tap drill and the clearance hole.Wire Size ChartAWG ampacity at 60, 75 and 90 °C, and the copper size for any load and run length with voltage drop taken into account.Wire Ampacity Derating ChartHow far to derate copper for hot rooms and full conduits: temperature factors, conductor-count factors and the derated amps for every size from 14 AWG to 500 kcmil.Bearing Size ChartEvery common deep-groove ball bearing from 604 to 6320 by bore code and series, with what 2RS, ZZ and C3 mean.IEC Motor Frame ChartEvery IEC frame from 63 to 355: shaft height, foot hole spacing, shaft size and the kW normally built on it, plus B3/B5/B14.NEMA Motor Frame ChartNEMA T frames from 56 to 449T with shaft height, foot holes, shaft size and typical HP — and what C, TS and JM mean.Motor Full-Load Current ChartFull-load amps for three-phase motors at 208 to 575 V with the copper size for each, and typical IEC amps at 400 V.Motor Efficiency Class ChartMinimum efficiency for IE1 to IE4 at every standard rating, and which class the EU lets you buy now.IE3/IE4 Motor Compliance Chart (EU 2026)Which IE class a new motor must be in the EU, whether an old IE1 or IE2 motor may keep running or be rewound, and what an upgrade saves — with a checker for your nameplate.
Why not just ask an AI?
ISO 261 · ASME B1.1Checked against the standard
Every number comes from the table or the formula in the standard. A chatbot
has given 7.5 mm for an M8 tap drill; it's 6.8 mm, and here it always will be.d − PThe working, not just the answer
Each page shows how the number was reached, so you can check it — and quote it
to someone who asks.A4 · LetterSomething to pin on the wall
Print the chart once and stop looking it up. It has a QR code back to the
page it came from.Get the next chart before it's on the site
The Shop Sheet, once a month: one new printable chart, and one standards gotcha that catches people out — the kind of wrong number a forum thread or an AI answer gives with total confidence. No sales emails.
Calculators
110 calculators for the numbers no chart holds — each with the working shown. Nothing you type leaves your device.
Electronics
Ohm's law, dividers, filters and the sums you do before you reach for the soldering iron.
Ohm's Law CalculatorGive any two of voltage, current, resistance or power — get the other two.Resistor Colour Code CalculatorRead a resistor from its bands, in 4, 5 or 6-band form.Voltage Divider CalculatorOutput voltage, current and power for a two-resistor divider.LED Resistor CalculatorThe series resistor an LED needs, with the nearest standard value.Series & Parallel Resistance CalculatorTotal resistance of any number of resistors, in series or parallel.RC Filter & Time Constant CalculatorCutoff frequency, time constant and rise time for an RC pair.Voltage Drop CalculatorVoltage lost in a copper run, and whether the gauge is adequate.Battery Life CalculatorHow long a battery lasts at a given load, with a realistic derating.Wire Size CalculatorThe smallest wire that carries the current and stays inside the voltage drop limit.Three-Phase Power CalculatorkW, kVA, kVAR and line current, with the √3 in the right place.Transformer CalculatorTurns ratio, winding currents and core size from the voltages and rating.555 Timer CalculatorFrequency, duty cycle and pulse width for astable and monostable 555 circuits.PCB Trace Width CalculatorTrace width for a given current and temperature rise, to IPC-2221.LC Resonance & Reactance CalculatorResonant frequency, reactance, impedance and Q for an LC circuit.Power Factor Correction CalculatorThe capacitor bank needed to raise power factor, and what it saves.Op-Amp Gain CalculatorGain, output voltage and bandwidth for the standard op-amp configurations.Decibel CalculatorConvert between dB, dBm, watts and voltage ratios — with the factor of 10 or 20.
Computing & data
Subnets, bases, bandwidth, colour and entropy.
Image ConvertertoolPNG, JPEG and WebP, with resizing — entirely in your browser.CSV to JSON ConvertertoolConvert between CSV and JSON, both directions, in your browser.QR Code GeneratortoolMake a QR code for a link, wifi network or contact — encoded in your browser, never uploaded.Hash GeneratortoolMD5, SHA-1, SHA-256 and SHA-512 for text or a file — computed in your browser.Password GeneratortoolStrong random passwords and passphrases, generated in your browser with real entropy.JSON Formatter & ValidatortoolFormat, minify and validate JSON — with the error pointed at, not just reported.Base64 Encoder & DecodertoolText or files to Base64 and back, including the URL-safe variant and data URIs.JWT DecodertoolRead the header and claims inside a JSON Web Token, with the timestamps in plain English.UUID GeneratortoolVersion 4 and version 7 UUIDs in bulk, plus a decoder for one you already have.Unix Timestamp ConvertertoolUnix time to a readable date and back, in seconds or milliseconds, UTC or local.Image CompressortoolCompress a photo to a target file size — 100 KB, 500 KB, whatever the form demands.Word & Character CountertoolWords, characters, sentences and reading time — counted as you type, never uploaded.Case ConvertertoolSentence case, Title Case, camelCase, snake_case and the rest — in one click.Diff CheckertoolCompare two texts and see exactly what changed — line by line, word by word.Lorem Ipsum GeneratortoolPlaceholder text by paragraphs, sentences or words — classic Latin or plain English.Subnet CalculatorNetwork, broadcast, host range and mask for any IPv4 CIDR block.Number Base ConverterConvert between decimal, binary, hexadecimal and octal.Download Time CalculatorHow long a transfer takes, and the units people keep confusing.Aspect Ratio CalculatorResize without distortion — give three numbers, get the fourth.Colour ConverterHEX, RGB, HSL and the contrast ratio against black and white.Password Entropy CalculatorHow much real randomness a password has, and how long it survives.Uptime & SLA CalculatorAllowed downtime for any number of nines, and the availability a given outage leaves you.RAID Capacity CalculatorUsable capacity, fault tolerance and write penalty for every common RAID level.Video Bitrate & File Size CalculatorFile size, bitrate or duration — plus what the resolution actually needs.
Engineering & build
Gears, torque, concrete, roofs and the quantities you have to order before you start.
Spur Gear GeneratortoolInvolute spur gears from module and tooth count — download SVG or DXF.Finger Joint Box GeneratortoolLaser-cut boxes with finger joints — enter three dimensions, download the cut file.Bolt Circle GeneratortoolHole positions on a pitch circle, with coordinates and a cut file.Gear Ratio CalculatorRatio, output speed and torque multiplication for a gear pair or train.Torque CalculatorTorque from force and radius, converted between every common unit.Pulley & Belt CalculatorDriven speed, ratio and belt length for a two-pulley drive.Kinetic & Potential Energy CalculatorEnergy and momentum of a moving or raised mass.Projectile Motion CalculatorRange, peak height and flight time for a launch angle and speed.Concrete CalculatorVolume of concrete for a slab, footing or column, and bags needed.Roof Pitch CalculatorPitch, angle, rafter length and the area multiplier.Paint CalculatorHow much paint a room needs, after doors, windows and coats.Board Foot CalculatorBoard feet and cost for rough lumber.Tile & Flooring CalculatorTiles, boxes and adhesive for a floor or wall.Electricity Cost CalculatorWhat an appliance costs to run, per day, month and year.BTU & Air Conditioner Size CalculatorCooling capacity a room needs, adjusted for the things that matter.Molarity & Dilution CalculatorConcentration, mass needed, and the dilution equation.Ideal Gas Law CalculatorSolve PV = nRT for whichever term you are missing.Tap Drill & Thread Size CalculatorTap drill size, clearance hole and thread engagement for metric and unified threads.Cutting Speed, RPM & Feed Rate CalculatorSpindle speed and feed from surface speed and chip load — milling, turning, drilling.Sheet Metal Bend Allowance CalculatorBend allowance, bend deduction and flat pattern length from the K-factor.Bolt Torque CalculatorTightening torque from size, grade and lubrication — with the preload it produces.Beam Deflection CalculatorMaximum deflection, moment and bending stress for the standard load cases.Section Modulus & Moment of Inertia CalculatorArea, I, section modulus and weight per metre for the common structural shapes.Stress, Strain & Elongation CalculatorAxial stress, strain, extension and safety factor from load and section.Belt Length & Pulley CalculatorBelt length, wrap angle and centre distance for open and crossed drives.Compression Spring CalculatorSpring rate, shear stress and solid height from wire size and coil geometry.Hydraulic Cylinder Force CalculatorPush and pull force, speed and flow demand from bore, rod and pressure.Pipe Flow & Pressure Drop CalculatorVelocity, Reynolds number and friction pressure loss in a round pipe.Pump Power CalculatorHydraulic power, shaft power, motor size and running cost from flow and head.Thermal Expansion CalculatorLength change with temperature, and the stress if the part cannot move.Bearing Life CalculatorL10 life in revolutions and hours from dynamic capacity, load and speed.Stair CalculatorRiser height, tread depth, stringer length and the code checks, from total rise.Rebar CalculatorBar count, total length, weight and laps for a slab or footing mat.Tank Volume CalculatorTotal and filled volume for cylindrical, rectangular and spherical tanks.Drywall CalculatorSheets, screws, tape and compound for a room, minus the openings.Gravel, Soil & Mulch CalculatorVolume, weight and bag count for any loose material spread to a depth.Wall Framing CalculatorStuds, plates, headers and noggins for a timber-framed wall.
Health & body
Body composition, energy needs and the dates that matter.
BMI CalculatorBody mass index, with the category and healthy weight range.BMR & TDEE CalculatorResting metabolic rate and daily calorie needs by activity level.Body Fat CalculatorBody fat percentage using the US Navy circumference method.Ideal Weight CalculatorFour established formulas, plus the healthy BMI range.Calorie Needs CalculatorDaily calories and macronutrient split for a weight goal.Water Intake CalculatorDaily fluid target adjusted for body weight, activity and climate.Due Date CalculatorEstimated due date, current stage and trimester dates.Ovulation CalculatorFertile window and ovulation date from your cycle.
Maths
The workings you used to do on paper, done exactly.
Graphing CalculatortoolPlot functions, zoom and trace — with the maths parsed, not evaluated.Percentage CalculatorEvery percentage question, answered at once.Fraction CalculatorAdd, subtract, multiply and divide fractions, simplified.Ratio CalculatorSimplify ratios, scale them, and solve for a missing term.Mean, Median & Mode CalculatorEvery summary statistic for a list of numbers.Standard Deviation CalculatorPopulation and sample standard deviation, variance and standard error.Quadratic Equation SolverRoots, vertex and discriminant for ax² + bx + c = 0.Triangle CalculatorMissing side, area, perimeter and angles of a right triangle.Circle CalculatorArea, circumference, diameter and radius from any one of them.GCD & LCM CalculatorGreatest common divisor and lowest common multiple, with factors.Scientific Notation ConverterConvert between decimal, scientific and engineering notation.
Everyday
Dates, units, journeys, grades and the small sums of ordinary life.
Age CalculatorExact age in years, months and days — plus every other unit.Date Difference CalculatorTime between two dates, in every unit, with or without weekends.Date Add & Subtract CalculatorAdd or subtract days, weeks, months or years from a date.Time Duration CalculatorHours and minutes between two times, with breaks deducted.Unit ConverterLength, weight, temperature, volume, area and speed.Fuel Cost CalculatorWhat a journey costs in fuel, and per person when shared.Speed, Distance & Time CalculatorSolve for any one of the three, plus pace.GPA CalculatorWeighted grade point average on a 4.0 scale.Random Number GeneratorRandom integers in a range, with or without duplicates.Sleep CalculatorBedtimes and wake times aligned to 90-minute sleep cycles.