Free chi-square calculator — run goodness of fit tests and tests of independence with full (O−E)²/E working tables, p-values, critical values, and Cramér’s V effect size. Supports contingency tables up to 6×6
Free arc length calculator — find arc length of circle arcs (s=rθ), functions (∫√(1+f’²)dx), parametric and polar curves. Also finds radius from arc length using the sagitta-chord formula. Full step-by-step working
Standard atmosphere calculator — find temperature, pressure, density, and speed of sound at any altitude using the ISA model. Includes density altitude calculator, pressure altitude converter, and full ISA reference table from sea level to 80km
Air properties calculator — find density, dynamic viscosity, kinematic viscosity, specific heat (cp, cv), thermal conductivity, Prandtl number, and speed of sound at any temperature. Includes molar mass of air (28.9647 g/mol) and a complete reference table from −50°C to 1000°C
Free density calculator — solve ρ=m/V for density, mass, or volume, find density of cylinders and spheres, use water displacement, and look up water density in kg/m³, lb/ft³, g/cm³, and lb/gal at any temperature
Free uniform circular motion calculator — solve for period, frequency, angular velocity, centripetal acceleration, centripetal force, and normal force. Full UCM formula reference and AP Physics 1 worked examples
Free variance calculator. Calculate sample variance (÷n−1) or population variance (÷n), coefficient of variation (CV%), and variance percentage (% change between two numbers) — with complete step-by-step working for each
Free margin of error calculator. Find MOE from sample statistics or proportions using MOE = z*(or t*) × standard error, build a confidence interval, or solve the required sample size for a target margin of error — with full step-by-step working
Free standard error calculator. Calculate the standard error of the mean (SEM = s/√n) or the standard error of estimate for regression (SEE = √(SSres/(n−k−1))) with complete step-by-step working
Free critical value calculator for t, z, and chi-square distributions. Find t critical values, z critical values, and chi-square critical values instantly with confidence level or alpha input, step-by-step working, and printable reference tables