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

Sample Size for Margin of Error of a Proportion Calculator

Compute the minimum sample size needed for a desired margin of error E around a proportion p̂ at a given confidence leve...

basic

5,882 4.9 1 min

Math / Geometry

Distance from Point to Plane Calculator

Compute the perpendicular distance from a 3-D point (x₀, y₀, z₀) to the plane a·x + b·y + c·z + d = 0, using d_pt = |a·x...

basic

12,793 3.9 1 min

Physics / Electricity

Magnetic Force Calculator

Compute the magnetic component of the Lorentz force on a charged particle moving through a magnetic field.

basic

21,470 4.0 1 min

Ecology / Energy

Electricity Bill Calculator

Estimate the monthly electricity cost of an appliance from its wattage, daily use, and your tariff.

basic

17,116 4.1 1 min

Math

Wilson-Score Confidence Interval for a Proportion Calculator

Compute the Wilson-score confidence interval for a binomial proportion p̂ = x/n. Unlike the standard Wald CI, the Wilson...

basic

13,265 4.3 1 min

Chemistry / Solutions

Dilution Calculator

Use C1V1 = C2V2 to plan solution dilutions accurately.

basic

6,665 4.0 1 min

Math / Percentage

Weighted Grade Calculator

Compute a course grade as a weighted average of up to four components (e.g. homework, quizzes, midterm, final), given ea...

basic

5,906 4.5 1 min

Chemistry / Solutions

Combined Gas Law Calculator

Find the missing pressure, volume, or temperature using the combined gas law for a fixed amount of gas.

basic

20,335 4.1 1 min

Sports

Volleyball Spike Jump Height & Reach Calculator

Calculates a volleyball player's spiking height and compares it to standard net height from standing reach and vertical...

basic

19,057 3.9 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

12,417 4.3 1 min

Math / Geometry

Rhombus Area Calculator

Compute the area of a rhombus from the lengths of its two diagonals.

basic

19,724 4.3 1 min

Math

Negative Binomial Distribution PMF Calculator

Compute the negative binomial PMF — the probability that the r-th success occurs on the k-th trial, given a per-trial su...

basic

22,752 4.8 1 min

Showing 253 to 264 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

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Daniel Oh

Sample Size for Margin of Error of a Proportion Calculator

Distance from Point to Plane Calculator

Magnetic Force Calculator

Electricity Bill Calculator

Wilson-Score Confidence Interval for a Proportion Calculator

Dilution Calculator

Weighted Grade Calculator

Combined Gas Law Calculator

Volleyball Spike Jump Height & Reach Calculator

Geometric Series Finite Sum Calculator

Rhombus Area Calculator

Negative Binomial Distribution PMF Calculator

Standard Deviation in Five Minutes

Percentages Without the Headache

Reviewed by Daniel Oh

Young's Rule Pediatric Dose Calculator