计算器
Amount of substance
Find mass, molar mass or amount in moles.
Arithmetic calculator
Add, subtract, multiply or divide two numbers.
BIN / OCT / DEC / HEX converter
Convert arbitrarily large integers between numeral systems.
BMI calculator
Body mass index and reference healthy-weight range.
Bitcoin mining profitability
ASIC revenue, electricity, J/TH, break-even tariff and payback.
Brick & block calculator
Masonry units and mortar for walls, minus door and window openings.
Capacitor and RC circuit
Time constant, cutoff, charge and stored energy.
Circle area
Calculate a circle from its radius, diameter or circumference.
Color picker and converter
Pick a color, convert HEX/RGB/HSL and inspect contrast.
Compound interest
Project balance growth with regular contributions.
Concrete & footing calculator
Slab, strip and pier foundations with concrete volume, premix bags and component materials.
Constant-acceleration motion
Final velocity, displacement and average speed.
Cron expression generator and parser
Build or parse five-field Cron and preview the next five runs.
Crypto investment return
Net crypto profit, ROI and break-even price after trading fees.
Daily calorie needs
BMR and maintenance calories using Mifflin–St Jeor.
Fraction arithmetic
Add, subtract, multiply and divide ordinary fractions.
Fuel consumption
L/100 km, km/L and US miles per gallon.
Gear ratio
Output speed and torque for a pair of gears.
Hash generator, validator and encoder
MD5/SHA hashes, Base64 and URL encoding with optional validation.
Hydraulic cylinder force
Extension and retraction force from pressure and diameters.
IPv4 / IPv6 subnet calculator
CIDR, masks, network ranges, host counts and IPv4 broadcast addresses.
JSON / YAML / XML / CSV converter
Validate and transform configuration and tabular data formats.
Loan and mortgage payment
Periodic annuity payment, total paid and interest.
Mechanical energy
Kinetic, potential and total mechanical energy.
Molar concentration
Find molarity, amount of substance or solution volume.
Newton's second law
Find force, mass or acceleration from the other two.
Ohm's law and DC power
Derive voltage, current, resistance and power from any compatible pair.
Percentage change
Compare an old and a new value.
Percentage of a number
Find any percentage of a number.
Powers and roots
Calculate powers, square, cube and arbitrary roots.
Property cap rate & ROI calculator
NOI, cap rate, cash-on-cash return, NPV, IRR and exit value for a property investment.
Proportion solver
Find one missing value in a : b = c : d.
Quadratic equation solver
Solve ax² + bx + c = 0 over real or complex numbers.
Rectangle
Area, perimeter and diagonal from length and width.
Roofing & rafter calculator
Roof area, pitch geometry, rafter length and material quantities.
Series and parallel resistors
Equivalent resistance for two resistors.
Simple interest
Interest and final amount without compounding.
Sphere
Volume, surface area and diameter of a sphere.
Torque from force
Calculate torque from force, lever arm and angle.
Triangle by three sides
Area, perimeter and angles using Heron's formula.
Trigonometry
Find sine, cosine and tangent of an angle.
pH calculator
pH, pOH and hydroxide concentration at 25 °C.
2D vector analysis
Magnitudes, dot and cross products and angle between vectors.
2×2 linear system
Solve two linear equations using Cramer's rule.
2×2 matrix
Determinant, trace, norm and inverse of a 2×2 matrix.
Belt drive
Driven speed, ratio and belt linear speed.
Body surface area
Estimate body surface area with the Mosteller formula.
Complex numbers
Add, subtract, multiply or divide complex numbers.
Cone
Volume, slant height and surface areas of a cone.
Cylinder
Volume, base, lateral and total surface areas.