# Proportion Calculator

> Solve any proportion for x — free, fast and exact.


## Posts

- [Hello world!](https://proportioncalculatorfree.com/hello-world/): Welcome to WordPress. This is your first post. Edit or delete it, then start writing!

## Pages

- [Methodology](https://proportioncalculatorfree.com/methodology/): This page explains how our calculators work: the formulas they use, how we test them, and what their limits are.
- [About](https://proportioncalculatorfree.com/about/): Proportion Calculator Free is a free online toolkit for solving proportions — from a simple a/b = c/d problem in 10th grade math to a two-proportion z-test in a statistics course.
- [Statistics](https://proportioncalculatorfree.com/statistics/): Welcome to the Statistics hub.
- [Math](https://proportioncalculatorfree.com/math/): Welcome to the Math hub.
- [Sample Size for Proportion](https://proportioncalculatorfree.com/sample-size-for-proportion/): How many people do you need to survey?
- [Sample Proportion](https://proportioncalculatorfree.com/sample-proportion/): The sample proportion p̂ (p-hat) is the proportion in a sample: p̂ = x ÷ n, where x is the number of successes and n is the sample size.
- [Two-Proportion Confidence Interval](https://proportioncalculatorfree.com/two-proportion-confidence-interval/): A two-proportion confidence interval estimates the difference between two population proportions, p1 − p2, from two independent samples.
- [Proportion Confidence Interval](https://proportioncalculatorfree.com/proportion-confidence-interval/): A proportion confidence interval gives a range of plausible values for a population proportion, based on a sample.
- [Two-Proportion Z-Test](https://proportioncalculatorfree.com/two-proportion-z-test/): A two-proportion z-test compares the proportions from two independent groups — for example, the share of men and women who support a policy, or the success rate of two treatments.
- [One-Proportion Z-Test](https://proportioncalculatorfree.com/one-proportion-z-test/): A one-proportion z-test checks whether a sample proportion is far enough from a claimed population proportion to be surprising.
- [Golden Proportion](https://proportioncalculatorfree.com/golden-proportion/): The golden proportion, also called the golden ratio, is the number φ (phi) = 1.6180339887… It is the ratio where a/b = (a + b)/a — the whole relates to the longer part exactly as the longer part relates to the shorter part.
- [Proportional Scale](https://proportioncalculatorfree.com/proportional-scale/): Proportional scale is how maps, models and drawings shrink or enlarge real life without changing its shape.
- [Percent Proportion](https://proportioncalculatorfree.com/percent-proportion/): A percent proportion is the proportion part/whole = percent/100.
- [Direct and Inverse Proportion](https://proportioncalculatorfree.com/direct-and-inverse-proportion/): Some quantities grow together, and others grow apart. In a direct proportion, y = kx: doubling x doubles y.
- [Proportional Relationship](https://proportioncalculatorfree.com/proportional-relationship/): A proportional relationship is a relationship between two quantities where one is always a constant multiple of the other: y = kx.
- [Ratio and Proportion](https://proportioncalculatorfree.com/ratio-and-proportion/): A ratio compares two quantities, and a proportion says two ratios are equal.
- [Proportion Calculator](https://proportioncalculatorfree.com/): A proportion calculator that solves a/b = c/d for x in seconds.


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