All calculators

80 tools so far, each with its formula, a worked example and its assumptions. More are added in tested batches.

Angle Weight CalculatorWeight of equal and unequal angle (L-section) per metre and per piece.Material Weight Area CalculatorArea and perimeter of rectangles, triangles, trapezoids and ellipses.Units & Geometry Aspect Ratio & Image Resize CalculatorSimplest aspect ratio, nearest common ratio, resized and cropped image dimensions.Computer & IT Assembly Line Balancing CalculatorCycle time, minimum workstations, line efficiency and balance delay for an assembly line.Industrial & Manufacturing Battery Runtime CalculatorEstimated running time of a battery from its capacity and the load power or current.Electrical Engineering Belt & Pulley CalculatorDriven pulley speed, ratio, belt speed and belt length for a two-pulley drive.Mechanical Engineering Binary Arithmetic CalculatorAdd, subtract, multiply or divide two binary numbers, with results in binary and decimal.Computer & IT Binary, Decimal, Hex & Octal ConverterConvert whole numbers between base 2, 8, 10 and 16 — exact for any size, with two’s complement.Computer & IT Bits, Bytes & Storage Unit ConverterConvert bits and bytes between decimal (KB, MB, GB) and binary (KiB, MiB, GiB) units.Computer & IT Bolt Tightening Torque EstimatorTightening torque from preload (T = K·F·d), preload from torque, or a preload target from proof strength.Mechanical Engineering Bricks & Blocks CalculatorNumber of bricks or blocks for a wall, with door and window openings deducted.Civil & Construction Capacitors in Series & Parallel CalculatorTotal capacitance of up to six capacitors in parallel and in series.Electrical Engineering CIDR & Subnet Mask ConverterCIDR prefix ↔ subnet mask, with wildcard mask, host bits and number of addresses.Computer & IT Circle CalculatorArea, circumference, radius and diameter — enter any one of them.Units & Geometry CNC Machining Cycle Time EstimatorCycle time and parts per hour from cutting moves, rapids, tool changes and handling.Machining & Workshop Concrete Volume CalculatorConcrete volume for slabs, footings, columns and beams, with optional wastage.Civil & Construction Cutting Speed & Spindle RPM CalculatorSpindle speed from cutting speed and diameter — or cutting speed from RPM.Machining & Workshop Cycle Time & Production Capacity CalculatorHow many parts per hour, day and week a machine or line can make.Industrial & Manufacturing Cycle Time CalculatorObserved average time per unit from operating time and units completed.Industrial & Manufacturing Data Transfer & Download Time CalculatorHow long a download, upload or network copy takes, from file size and link speed.Computer & IT Download Speed Converter (Mbps ↔ MB/s)Convert Mbps to MB/s and back, and see the practical speed you might actually get.Computer & IT DPMO & Sigma Level CalculatorDefects per million opportunities, DPU, yield and Six Sigma level.Industrial & Manufacturing Economic Order Quantity (EOQ) CalculatorThe order size that minimises total ordering and holding cost.Industrial & Manufacturing Electricity Cost CalculatorEnergy use (kWh) and running cost of any appliance or machine.Electrical Engineering Excavation Volume CalculatorIn-place volume of pits and trenches, plus optional loose (bulked) volume.Civil & Construction Fits Calculator – Clearance, Transition & InterferenceFit type and maximum/minimum clearance or interference of a hole and shaft.Metrology & Quality Gear Ratio CalculatorGear ratio from teeth or speeds, with output speed, torque and direction for a gear pair.Mechanical Engineering Hollow Section (SHS / RHS) Weight CalculatorWeight of square and rectangular tube (SHS / RHS) including corner radii.Material Weight Hydraulic Cylinder Force CalculatorPush and pull force of a hydraulic or pneumatic cylinder from bore, rod and pressure.Mechanical Engineering Image, Audio & Video File Size CalculatorExact uncompressed size of images, audio and raw video, or a bitrate-based estimate.Computer & IT Inch Fraction ↔ Decimal ↔ mm ConverterConvert fractional inches (like 3/8") to mm, or mm to the nearest inch fraction.Units & Geometry Inventory Turnover CalculatorInventory turns and days of inventory on hand from cost of goods sold.Industrial & Manufacturing IPv4 Subnet & Address Range CalculatorNetwork, broadcast and usable host range of an IPv4 subnet from CIDR or subnet mask.Computer & IT IPv6 Address Expander, Compressor & Prefix ToolValidate, expand and compress IPv6 addresses, identify the type, and find a prefix’s range.Computer & IT Lathe Change-Gear Calculator for Thread CuttingFind or check change gears for cutting a metric or TPI thread on your lathe.Machining & Workshop Lathe Turning Time CalculatorMachining time for a turning operation from length, feed and RPM or cutting speed.Machining & Workshop Limits of Size & Tolerance CalculatorMaximum and minimum limits, tolerance and mean size from nominal size and deviations.Metrology & Quality Machining Cost & Tool Cost per Part CalculatorCost per part from machine rate, cutting and handling time, tool life and tool cost per edge.Machining & Workshop Measurement Uncertainty Calculator (GUM)Combined standard and expanded uncertainty from independent components (root-sum-square).Metrology & Quality Mechanical Power & Work CalculatorPower from force and speed, from work and time, or for lifting a load.Mechanical Engineering Micrometer Least Count & Reading CalculatorLeast count from pitch and thimble divisions, and a micrometer reading with zero error.Metrology & Quality OEE CalculatorOverall Equipment Effectiveness from availability, performance and quality.Industrial & Manufacturing Ohm’s Law CalculatorEnter any two of voltage, current, resistance and power to find the others.Electrical Engineering Paint CalculatorLitres or gallons of paint for walls, using the coverage rate on your paint label.Civil & Construction Parallel Key Length EstimatorMinimum parallel-key length for shear and crushing, or the stresses in a given key.Mechanical Engineering PC Power Supply (PSU) Wattage EstimatorAdd up PC component power, apply headroom and find a suitable power supply size.Computer & IT Pipe Flow Rate & Velocity CalculatorFlow rate from average velocity and pipe inside diameter, or velocity from flow rate.Mechanical Engineering Pipe Weight CalculatorWeight per metre of pipe and round tube from outside diameter and wall thickness.Material Weight Plate Weight CalculatorWeight of a rectangular plate or sheet in steel, aluminium, copper and more.Material Weight Pressure & Hydrostatic Pressure CalculatorPressure from force over an area, or gauge and absolute pressure at a depth in a still liquid.Mechanical Engineering Production Batch Time CalculatorElapsed time, machine hours and shifts for a batch from set-up, cycle time and quantity.Industrial & Manufacturing Productivity CalculatorOutput per labour-hour, per machine-hour, or any output ÷ input ratio.Industrial & Manufacturing Rebar Weight CalculatorWeight of reinforcing steel bars (rebar / sariya) per metre, per bar and in total.Civil & Construction Reorder Point & Safety Stock CalculatorWhen to reorder: reorder point and safety stock from demand, lead time and service level.Industrial & Manufacturing Resistors in Series & Parallel CalculatorTotal resistance of up to six resistors in series and in parallel.Electrical Engineering Rolling Bearing Life Calculator (L10)Basic rating life L10 in revolutions and hours for ball or roller bearings, with reliability factor.Mechanical Engineering Round Bar Weight CalculatorWeight per metre and per piece of solid round bar or rod.Material Weight Safety Stock CalculatorSafety stock by four methods: fixed buffer, variable demand, variable lead time, or both.Industrial & Manufacturing Scrap Rate, Yield & First Pass Yield CalculatorScrap rate, yield, rework rate and first pass yield of a process.Industrial & Manufacturing Screen PPI & Pixel Density CalculatorPixels per inch, dot pitch and physical size of a screen from resolution and diagonal.Computer & IT Shaft Torsional Stress CalculatorTorsional shear stress and angle of twist of a round shaft, or the diameter needed.Mechanical Engineering Single & Three-Phase AC Power CalculatorkW, kVA, kVAR and current for single-phase and three-phase loads.Electrical Engineering Single-Point Thread Depth CalculatorThread depth, compound-slide infeed and an equal-area pass schedule for 60° threads.Machining & Workshop Spring Rate Calculator (Hooke’s Law)Spring rate, force or deflection using Hooke’s law — plus stored energy.Mechanical Engineering Square & Flat Bar Weight CalculatorWeight of solid square, rectangular and flat bar per metre and per piece.Material Weight Standard Time Calculator (Time Study)Normal time and standard time from a time study: observed time, rating and allowances.Industrial & Manufacturing Takt Time CalculatorThe pace of production needed to meet customer demand.Industrial & Manufacturing Tap Drill Size CalculatorTap drill diameter for ISO metric and UNC/UNF threads at your chosen % of thread.Machining & Workshop Taper Turning CalculatorTaper angle, compound setting, taper per foot and tailstock offset for turning tapers.Machining & Workshop Taylor Tool Life CalculatorTool life from cutting speed with V·Tⁿ = C, the speed for a target life, or n and C from two tests.Machining & Workshop Thread Pitch, TPI & Lead CalculatorConvert pitch in mm to TPI and back, and find the lead of multi-start threads.Machining & Workshop Tile CalculatorNumber of tiles and boxes for a floor or wall, including grout joints and wastage.Civil & Construction Tolerance Stack-Up Calculator (Worst Case)Worst-case maximum and minimum gap of a 1-D dimension chain, with an RSS comparison.Metrology & Quality Torque & Shaft Power CalculatorTorque from force × lever arm or from power and speed, and shaft power from torque and speed.Mechanical Engineering Transformer Turns Ratio CalculatorTurns ratio, secondary voltage or secondary turns of an ideal transformer.Electrical Engineering Turning Material Removal Rate CalculatorMetal removal rate (cm³/min) of a turning cut from diameter, depth of cut, feed and speed.Machining & Workshop Unit ConverterConvert length, area, volume, mass, pressure, force, torque, energy, power, temperature and more.Units & Geometry Vernier Caliper Least Count & Reading CalculatorLeast count of a vernier scale, and the reading with zero-error correction.Metrology & Quality Voltage Drop CalculatorEstimated voltage drop, % drop and cable losses for DC, single-phase and three-phase circuits.Electrical Engineering Volume & Surface Area CalculatorVolume, capacity in litres and surface area of boxes, cylinders, spheres and cones.Units & Geometry