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

Statistics

Sample Excess Kurtosis of 5 Numbers Calculator

Compute the adjusted excess kurtosis g₂ of a 5-number list (zero for a normal distribution; positive = heavier tails / m...

basic

13,537 4.2 1 min

Physics / Electricity

Ohm's Law Calculator

Relate voltage, current, and resistance — solve for whichever variable is missing.

basic

14,511 4.7 1 min

Finance

Gross Margin Return on Inventory (GMROI) Calculator

GMROI = Gross Margin ($) / Average Inventory Cost ($). A ratio > 1 means every dollar in inventory earns more than $1 in...

basic

24,325 4.0 1 min

Physics / Mechanics

Centripetal Force Calculator

Compute the centripetal force required to keep an object moving in a circle of given radius at a given speed.

basic

18,832 4.7 1 min

Sports

Ski Resort Vertical Descent and Runs per Day Calculator

Estimates total vertical descent (number of runs × vert per run), lift time vs ski time, and calories burned: ~400 kcal/...

basic

12,709 4.9 1 min

Health

Surgical Apgar Score from EBL, Lowest HR, and Lowest MAP Calculator

Compute the Surgical Apgar Score (Gawande et al. 2007), a 10-point post-operative risk-of-major-complication score from...

basic

7,090 4.4 1 min

Physics / Mechanics

Doppler Effect Calculator

Compute the frequency observed by a stationary observer when a source moves at velocity v_s, using the classical Doppler...

basic

22,365 3.8 1 min

Math / Geometry

Cube Surface Area Calculator

Calculate the surface area, volume, and space diagonal of a cube from a single side length.

basic

19,002 4.7 1 min

Health

Glasgow Coma Scale (GCS) Calculator

Calculates the Glasgow Coma Scale total score from eye opening, verbal response, and motor response to assess the depth...

basic

22,655 4.7 1 min

Food / Drinks

Cocktail Dilution Calculator

Estimate the final ABV of a stirred or shaken cocktail given starting ABV, total liquid volume, and the typical 25–40% d...

basic

12,507 4.7 1 min

Health

Corrected QT Interval (QTc) Using Bazett's Formula Calculator

Calculates the corrected QT interval QTc = QT / √(RR), where RR = 60/HR (seconds). Normal QTc: <440 ms (male), <460 ms (...

basic

4,515 4.5 1 min

Math

Hedges' g Effect Size Calculator

Compute Hedges' g — Cohen's d adjusted for small-sample bias — from the mean difference, pooled SD, and total degrees of...

basic

21,360 4.6 1 min

Showing 337 to 348 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 Excess Kurtosis of 5 Numbers Calculator

Ohm's Law Calculator

Gross Margin Return on Inventory (GMROI) Calculator

Centripetal Force Calculator

Ski Resort Vertical Descent and Runs per Day Calculator

Surgical Apgar Score from EBL, Lowest HR, and Lowest MAP Calculator

Doppler Effect Calculator

Cube Surface Area Calculator

Glasgow Coma Scale (GCS) Calculator

Cocktail Dilution Calculator

Corrected QT Interval (QTc) Using Bazett's Formula Calculator

Hedges' g Effect Size Calculator

Standard Deviation in Five Minutes

Percentages Without the Headache

Reviewed by Daniel Oh

Young's Rule Pediatric Dose Calculator