# Probability-Distributions

> Statistical distribution calculator and visualizer for continuous and discrete probability functions. (iPhone/iPad app by Matthew Bognar.)

- Source: https://appshunter.io/ios/app/probability-distributions/id889106396 (this page in markdown: same URL + `.md`)
- Developer: [Matthew Bognar](https://appshunter.io/developer/889106399)
- Category: Education
- Price: $1.99
- Rating: 4.90/5 from 193 App Store ratings · 70 written reviews indexed
- Age rating: 17+
- Requires: iOS 14.0 · 2 MB
- Languages: American English
- Released: 2014-06-22
- Data updated: 2026-08-24
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/probability-distributions/id889106396/reviews.md

## What is Probability?

Compute probabilities, determine percentiles, and plot the probability density function for the normal (Gaussian), t, chi-square, F, exponential, gamma, beta, log-normal, Pareto, and Weibull distributions.

Compute probabilities, approximate percentiles, and plot the probability mass function for the binomial, geometric, hypergeometric, Poisson, and negative binomial distributions.

## Key features

- Compute probabilities
- Determine percentiles
- Plot probability density function
- Plot probability mass function
- Supports 10+ continuous distributions
- Supports 5+ discrete distributions

## Chart rankings

- #34 in Top Paid · Education (US App Store)

## What do users think of Probability?

Overall sentiment: positive

**Pros**

- 👍 Easy to use interface
- 📊 Great for probability distributions
- 💡 Useful for checking work and homework
- 💰 Free advanced functions
- 📈 Visualizes data and distributions
- 🚀 Quick calculations
- 📚 Valuable educational tool
- 💯 Accurate results

**Cons**

- 🚫 Not allowed on some exams
- 🤔 Some users want more features

**Most requested features**

- Exam mode similar to Geogebra
- Poisson distribution
- Allow setting plot boundaries (e.g., for Beta distribution)
- Make formulae available in offline mode
- Clearly introduce parameters
- Add options after graph rendering (area above, between, outside values)
- Consistent terms for df across distributions

## Recent user reviews (10 of 70)

All indexed reviews: https://appshunter.io/ios/app/probability-distributions/id889106396/reviews.md

### 3/5 — Good for education but needs improvement

*2025-11-12*

As a teacher I need exam mode such as Geogebra to use during exams

### 5/5 — Finally!  A simple, free N(0, 1) calculator.

*2024-03-31*

Subject line says it all.  P(Z<x) for normal and a bunch more for essential statistical tests.  THANK YOU!!!!

### 5/5 — look what it pooped out

*2022-02-09, version 0.9.2*

absolutely love this man, great for checking work and giving hints to solutions!

### 5/5 — Sick App

*2021-10-04*

I love probability distributions.

### 1/5 — Wow just wow.

*2020-12-31, version 0.9.2*

I met my wife because of this app. Needless to say I’m not happy and it’s this apps fault.

### 5/5 — iPhone SE (2020) issue has been fixed

*2020-11-13*

Works perfectly now. Much better than using tables.

**Developer response:** Thanks for the update! I'm glad it is working well.

### 4/5 — very good, but new problem appeared in iphone se

*2020-10-27*

Now the app doesn't show if I'm using P(x >) or P(x <). It cuts off and only shows "P(." although it's not a huge problem since I can guess which option shows. I didn't have this problem in a previous version also.

### 5/5 — Amazing! Love it!

*2020-03-06, version 0.8*

Love the app. Saved me too many times 😬 One thing missing to make it the mathematic essential app. Poisson. Besides that, best thing I’ve come across.

### 5/5 — BOGNAR IS THE GOAT

*2020-02-12, version 0.8*

Goat status: 100%

### 5/5 — Does advanced functions for free!

*2019-11-19*

This could be really useful for students in college stats courses who are on a budget and can’t afford to buy a $100+ dollar graphing calculator. It does basic advanced functions like binomial pdf - for free.  I don’t know if it does invNorm or Z-Test calculations ( possibly not) but for a calculation app that you don’t have to pay for this is pretty great and was just what I was looking for.

## Frequently asked questions about Probability

### What does this app do?

This app allows you to compute probabilities, determine percentiles, and plot the probability density or mass functions for a variety of common statistical distributions. It covers both continuous and discrete probability models.

### What statistical distributions are supported?

The app supports over 10 continuous distributions including normal (Gaussian), t, chi-square, F, exponential, gamma, beta, log-normal, Pareto, and Weibull. It also supports 5+ discrete distributions like binomial, geometric, hypergeometric, Poisson, and negative binomial.

### Is this app free to use?

Yes, the application is completely free to use. There are no in-app purchases or advertisements, providing an uninterrupted experience for all users.

### Who would benefit from using this app?

This app is ideal for students learning statistics, researchers analyzing data, statisticians performing complex calculations, and anyone who needs to understand or visualize probability distributions in their work or studies.

## Version history (last 5 releases)

### 0.9.3 — 2025-07-13

Small UI changes. Updated Boost numerical library.

### 0.9.2 — 2020-11-13

Bug fixes for iOS 14.

### 0.9.1 — 2020-09-21

Fixes for iOS 14.

### 0.9 — 2020-09-21

Fixed compatibility issue with iOS-14.

### 0.8 — 2018-07-03

Small enhancements and bug fixes.

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-24.*