Free online science and maths tools

Fits a four-parameter logistic curve to assay data.

Checks how well a camera sensor suits a telescope in terms of image scale.

Shows what a telescope and camera combination will frame against sky targets.

Calculates magnification and exit pupil from telescope and eyepiece focal lengths.

Reference page with formulas and a calculator for stress and deflection of beams on two supports.

Computes binomial and cumulative probabilities for a set number of trials.

Demo of a browser 2D chemical structure sketcher.

Tests independence in a contingency table of up to five rows and columns using Pearson's statistic.

Interactive chi-square curve with p-values and critical values.

Finds chi-square probabilities and critical values.

Solves systems of congruences using the Chinese remainder theorem.

Finds the Laplace transform of a function with steps.

Breaks a number into primes with the steps shown.

Converts emissions or energy figures into everyday equivalents like miles driven.

Finds F-distribution probabilities and critical values.

Interactive chart of nuclides with decay modes and nuclear structure data.

Browse earthquake locations on a map with depth and time filters.

Interactive 3D walk-through of how a four-stroke engine turns fuel into motion.

Draws chemical structures in the browser and exports them as SMILES or molfile.

Shows AND, OR, NOT, NAND, NOR and XOR gate outputs as you toggle inputs.

Converts numbers among binary, decimal and hexadecimal.

Computes combinations and permutations with or without repetition.

Standard normal table with an interactive bell curve.

Calculates percentages, percent change and percent of a number.