Math calculators

Everyday arithmetic, algebra, and geometry — worked out clearly.

Percentages, fractions, ratios, geometry, and the little calculations that come up all the time — with formulas you can reuse anywhere.

Calculators

244

Topics: All Percentage (75) Fractions (4) Geometry (63)

Math / Percentage

Test Time Per Question Calculator

Compute the average minutes you can spend per question on a timed test from the total test length, the number of questio...

basic

10,874 4.1 1 min

Math

Paired t-Test Statistic Calculator

Compute the paired-samples t-statistic from the mean of the paired differences (d̄), the standard deviation of those dif...

basic

10,143 4.7 1 min

Math

Complex Number — Polar to Rectangular Calculator

Convert a complex number from polar form r∠θ (with θ in degrees) to rectangular form a + b·i, where a = r·cos(θ) and b =...

basic

8,294 4.6 1 min

Math

Sigmoid (Logistic) Function Calculator

Compute the standard logistic / sigmoid function σ(x) = 1 / (1 + e^(−x)) — the canonical S-shaped activation function an...

basic

6,938 4.2 1 min

Math

Trigonometric Sum-of-Angles Calculator

Compute sin(A+B), cos(A+B), and tan(A+B) from two angles A and B (in degrees), using the angle-addition identities sin(A...

basic

6,394 4.0 1 min

Math / Percentage

Odds to Probability Converter

Convert betting odds expressed as "X to Y for the event" into the implied probability of the event occurring, with the c...

basic

4,306 4.7 1 min

Math

Pearson r Correlation from Running Sums Calculator

Compute Pearson's product-moment correlation r directly from streaming sums Σx, Σy, Σxy, Σx², Σy², and sample size n. r...

basic

2,844 4.3 1 min

Math

Multinomial Coefficient from Three Counts Calculator

Compute the multinomial coefficient C(n; k₁, k₂, k₃) = n! / (k₁! · k₂! · k₃!), where n = k₁ + k₂ + k₃. This counts the d...

basic

2,784 4.0 1 min

Math

Sum of Cubes from 1 to n Calculator

Compute the closed-form sum of the first n positive cubes: 1³ + 2³ + ⋯ + n³ = (n·(n+1)/2)² = (Σk)². Note that the sum of...

basic

477 4.9 1 min

Math

Spearman Rank Correlation from Σd² Calculator

Compute the Spearman rank-order correlation coefficient ρ from the sum of squared rank differences and the number of pai...

basic

22,638 4.5 1 min

Math

AIC and BIC from Log-Likelihood Calculator

Compute the Akaike (AIC) and Bayesian (BIC) information criteria for model comparison from a fitted model's log-likeliho...

basic

22,326 3.9 1 min

Math

Vector Projection of a onto b Calculator

Compute the projection of vector a onto vector b in 3-D: proj_b a = (a · b / |b|²) · b. Reports the scalar projection co...

basic

21,944 4.7 1 min

Math / Geometry

Distance Between Two 3D Points

Compute the Euclidean distance between two points in 3D space, given their (x, y, z) coordinates.

basic

21,632 4.1 1 min

Math / Geometry

Spherical Cap Volume Calculator

Compute the volume of a spherical cap (the portion of a sphere cut off by a plane) from the sphere's radius and the cap'...

basic

21,599 3.8 1 min

Math / Geometry

Triangle Circumradius from Sides Calculator

Compute the circumradius R of a triangle from its three side lengths a, b, c: R = abc / (4·area), where area is computed...

basic

19,233 4.3 1 min

Math

Complex Number Multiplication Calculator

Multiply two complex numbers in rectangular form, returning the real and imaginary parts of the product, plus its modulu...

basic

17,760 4.1 1 min

Math / Geometry

Central Angle from Arc Length and Radius Calculator

Compute the central angle subtended at the centre of a circle by an arc of given arc length, using the radius: θ_radians...

basic

16,755 4.5 1 min

Math

Standard Deviation of Grouped Frequency Data Calculator

Compute the population standard deviation of grouped data from up to six (midpoint, frequency) pairs. First computes x̄...

basic

15,331 4.6 1 min

Math

Sample Skewness from Third Moment and Variance Calculator

Compute the sample skewness — the third standardized moment of a distribution — from the centred third moment m₃ = E[(X...

basic

14,995 4.1 1 min

Math

Catalan Number from n Calculator

Compute the n-th Catalan number C_n = (2n)! / ((n+1)! · n!). C_n counts non-crossing handshakes of 2n people, balanced p...

basic

11,752 4.8 1 min

Math

Log-Odds (Logit) from Probability Calculator

Compute the log-odds (logit) of a probability p: logit(p) = ln(p/(1−p)). The logit maps (0,1) to (−∞, +∞) and is the inv...

basic

9,701 4.8 1 min

Math

Gini Coefficient from Five Income-Quintile Shares Calculator

Compute the Gini coefficient of income inequality from the cumulative income shares of the five population quintiles. Af...

basic

8,524 5.0 1 min

Math / Percentage

Study Hours Per Credit Hour Calculator

Estimate weekly study hours required for a college course load using the rule of thumb that each credit hour requires 2–...

basic

7,824 4.3 1 min

Math

Geometric Series Finite Sum Calculator

Compute the sum of the first n terms of a geometric series with first term a and common ratio r: S_n = a · (1 − rⁿ) / (1...

basic

5,681 4.5 1 min

Showing 169 to 192 of 244 results

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Percentages, fractions, ratios, geometry, and the little calculations that come up all the time — with formulas you can reuse anywhere.

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Math calculators

Test Time Per Question Calculator

Paired t-Test Statistic Calculator

Complex Number — Polar to Rectangular Calculator

Sigmoid (Logistic) Function Calculator

Trigonometric Sum-of-Angles Calculator

Odds to Probability Converter

Pearson r Correlation from Running Sums Calculator

Multinomial Coefficient from Three Counts Calculator

Sum of Cubes from 1 to n Calculator

Spearman Rank Correlation from Σd² Calculator

AIC and BIC from Log-Likelihood Calculator

Vector Projection of a onto b Calculator

Distance Between Two 3D Points

Spherical Cap Volume Calculator

Triangle Circumradius from Sides Calculator

Complex Number Multiplication Calculator

Central Angle from Arc Length and Radius Calculator

Standard Deviation of Grouped Frequency Data Calculator

Sample Skewness from Third Moment and Variance Calculator

Catalan Number from n Calculator

Log-Odds (Logit) from Probability Calculator

Gini Coefficient from Five Income-Quintile Shares Calculator

Study Hours Per Credit Hour Calculator

Geometric Series Finite Sum Calculator