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

Sports

Broad Jump Power Output Calculator

Estimates average lower-body power from a standing broad (long) jump using distance and body mass via the Johnson & Baha...

basic

14,714 4.8 1 min

Math / Geometry

Cone Surface Area from Radius and Slant Calculator

Compute the lateral (curved) surface area, base area, and total surface area of a right circular cone given its base rad...

basic

16,535 3.9 1 min

Everyday Life / Shopping

Gift Cost Split Calculator

Compute how much each person owes when splitting a group gift, with optional shipping and an organizer's share.

basic

6,099 4.8 1 min

Statistics / Descriptive

Weighted Mean from Values and Frequencies Calculator

Calculates x̄_w = Σ(w_i · x_i) / Σw_i for up to six value/weight pairs. Used in grade calculations, portfolio returns, a...

basic

11,541 4.1 1 min

Statistics / Descriptive

Z-Score from Raw Score, Mean, and SD Calculator

Calculates the z-score: z = (X − μ) / σ, indicating how many standard deviations X is from the mean μ. Also computes the...

basic

15,648 3.9 1 min

Math / Fractions

LCM Calculator

Find the least common multiple of two or more whole numbers, with the full prime-factor breakdown.

basic

7,478 3.9 1 min

Everyday Life

Plant Watering Frequency & Volume Calculator

Estimates how often to water a plant and how much water to use from pot diameter, soil drainage, and light conditions.

basic

4,007 4.3 1 min

Other / Games

Chess Elo Expected Score Calculator

Compute the expected score (probability of winning) for player A against player B from their Elo ratings using E_A = 1 /...

basic

8,899 4.2 1 min

Math / Percentage

Complex Number Calculator

Add, subtract, multiply, or divide two complex numbers (a + bi) and (c + di), and see the result in both rectangular and...

basic

5,707 3.9 1 min

Biology / Human Body

Body Adiposity Index Calculator

Estimate body fat percentage using the Body Adiposity Index, an alternative to BMI based on hip circumference and height...

basic

10,859 4.9 1 min

Other / Tech

RAID Storage Capacity Calculator

Compute the usable storage capacity of a RAID array given the number of disks, the size per disk in TB, and the RAID lev...

basic

19,628 4.8 1 min

Math / Percentage

Standard Error of the Mean Calculator

Compute the standard error of the mean (SEM) — how precisely the sample mean estimates the population mean — from a list...

basic

20,841 4.2 1 min

Showing 61 to 72 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

22,628 5.0 1 min

Best Free Calculator

Browse categories

Daniel Oh

Broad Jump Power Output Calculator

Cone Surface Area from Radius and Slant Calculator

Gift Cost Split Calculator

Weighted Mean from Values and Frequencies Calculator

Z-Score from Raw Score, Mean, and SD Calculator

LCM Calculator

Plant Watering Frequency & Volume Calculator

Chess Elo Expected Score Calculator

Complex Number Calculator

Body Adiposity Index Calculator

RAID Storage Capacity Calculator

Standard Error of the Mean Calculator

Standard Deviation in Five Minutes

Percentages Without the Headache

Reviewed by Daniel Oh

Young's Rule Pediatric Dose Calculator