Featured contributor MSc Applied Statistics; 7 years in analytics and data tooling.

Daniel Oh

Senior Contributor, Math & Statistics

0 calculators 0 articles Member since Jun 2026

About

Daniel writes and reviews the math and statistics calculators. His explainers lean on worked examples, clean formulas, and obvious edge cases so readers can copy the logic straight into a spreadsheet.

He previously worked as a data scientist at a consumer-tech startup before moving into full-time writing and tooling.

Areas of expertise

Statistics Probability Percentages Data analysis

Education & credentials

BSc Mathematics — University of Toronto
MSc Applied Statistics — ETH Zürich

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

12,214 4.7 1 min

Other / Tech

Video Bitrate Calculator

Estimate the recommended H.264 video bitrate for a given resolution, frame rate, and motion-complexity factor (rule-of-t...

basic

3,192 4.2 1 min

Statistics

Cohen's d Standardised Effect Size Calculator

Calculates Cohen's d standardised effect size between two groups from their means and pooled standard deviation.

basic

8,308 4.6 1 min

Physics / Mechanics

Snell's Law Calculator

Compute the angle of refraction when light passes from a medium of refractive index n₁ into a medium of refractive index...

basic

18,684 3.8 1 min

Statistics / Probability

Negative Binomial Distribution Mean Calculator

Calculates the mean and variance of a negative binomial distribution from the number of required successes r and success...

basic

24,512 4.5 1 min

Statistics

ROC AUC (Trapezoid) from 5 Points Calculator

Compute the area under a ROC curve using the trapezoidal rule on 5 user-supplied (FPR, TPR) operating points (plus the i...

basic

24,558 4.7 1 min

Math / Percentage

Bisection Method Step Calculator

Perform one bisection-method step: compute the midpoint m of the bracket [a, b], evaluate the new bracket based on the s...

basic

19,366 4.2 1 min

Physics

CPU Instruction Execution Time from CPI and Clock Rate Calculator

Calculates CPU execution time = (instruction count × CPI) / clock_frequency, and MIPS = clock_frequency / (CPI × 10⁶).

basic

13,148 4.1 1 min

Statistics / Probability

Binomial Coefficient (n choose k) Calculator

Compute the binomial coefficient "n choose k" using factorials. Useful for combinations, Pascal's triangle, and binomial...

basic

9,041 4.5 1 min

Math / Fractions

Fraction Calculator

Add, subtract, multiply, and divide fractions — with automatic simplification.

basic

6,691 3.9 1 min

Physics / Mechanics

Impulse and Change in Momentum from Force and Time Calculator

Calculates impulse J = F · Δt and the resulting change in momentum. Given the object mass, also computes the change in v...

basic

2,519 4.3 1 min

Math / Geometry

Sphere Volume Calculator

Volume and surface area of a sphere from radius or diameter.

basic

13,312 4.4 1 min

Showing 37 to 48 of 566 results

explainer Statistics

Standard Deviation in Five Minutes

Standard deviation is "average distance from the average". That one sentence covers 90% of everything you ever need to remember about it.

Daniel Oh

Mar 20, 2026 3 min

tutorial Math

Percentages Without the Headache

Every "X% of Y" problem, every "what percent of", every percent-change question — written out the way you'd actually say them.

Daniel Oh

Jan 7, 2026 3 min

Reviewed by Daniel Oh

These calculators were technically reviewed by Daniel Oh for accuracy.

Health

Young's Rule Pediatric Dose Calculator

Calculate an age-based pediatric dose from a known adult dose using Young’s Rule. A quick educational tool for students...

basic

22,624 5.0 1 min

Best Free Calculator

Browse categories

Daniel Oh

Multinomial Coefficient from Three Counts Calculator

Video Bitrate Calculator

Cohen's d Standardised Effect Size Calculator

Snell's Law Calculator

Negative Binomial Distribution Mean Calculator

ROC AUC (Trapezoid) from 5 Points Calculator

Bisection Method Step Calculator

CPU Instruction Execution Time from CPI and Clock Rate Calculator

Binomial Coefficient (n choose k) Calculator

Fraction Calculator

Impulse and Change in Momentum from Force and Time Calculator

Sphere Volume Calculator

Standard Deviation in Five Minutes

Percentages Without the Headache

Reviewed by Daniel Oh

Young's Rule Pediatric Dose Calculator