Online calculators

Math

• Linear interpolator
• Quadratic interpolator
• 2D interpolator
• Cubic equations
• Radix (base) conversion
• Pythagorean triangle approximation

Statistics

• Binary sample size calculator
• Best line to fit three data points

• Distance from longitude and latitude
• How far is a degree at your longitude and latitude
• Maidenhead locator <-> coordinates

Music and acoustics

• Converting between frequency and musical notation
• Converting between frequency and barks
• Converting between phon and sone (loudness metrics)

Typography

• LaTeX commands to/from Unicode characters
• HTML entities to/from Unicode characters

Topology

• Homotopy groups of spheres

Science and engineering

• Predicting a child’s adult height
• Heat index
• Half-life calculator
• Wavelength to RGB
• Convert between wire gauge and diameter