Units of measurement

Many different units of measurement are used throughout Equus.

Equestria has two main units of length: the royal hoof and the standard hoof.

#### Royal hoof

The royal hoof (rH) was introduced as a way of standardizing measurements by using the exact length of Princess Celestia's hoof from back to front as a unit, although later on it was more precisely defined based on planetary measurements which are less prone to change.

A royal hoof is defined by the Equestrian Institute of Statistics to be precisely 1/150,000,000 of the circumference of Equus.

The average mare is 4.5 royal hooves tall and the average stallion is 5 royal hooves tall.

#### Standard hoof

The standard hoof (sH) was introduced as the hooves of an average Pony are significantly smaller than those of Celestia.

It approximates the length of an average Pony hoof as 3/4ths of a royal hoof, making it 1/200,000,000 of the circumference of Equus by definition.

The average mare is 6 standard hooves tall and the average stallion is 6.7 standard hooves tall.

#### Multiples

Legs are equivalent to 3 hooves. The standard leg (sL) equals 3 standard hooves and the royal leg (rL) equals 3 royal hooves.

Legs are also called paces as the length of a Pony's leg is similar to the distance covered by taking two steps.

Steps (sS and rS) or half-paces are equivalent to 1.5 hooves.

The length of 60 standard paces is known as a toss (T).

The length of 60 tosses is known as a walk (W).

The length of 60 walks is known as a journey (J).

### Area

The basic unit of area in Equestria is the Equestrian acre, which is equivalent to a square of a one Equestrian standard pace side.

### Volume

The basic unit of volume in Equestria is the Equestrian gallon or cubic standard hoof.

It has a subdivision, the Equestrian cup (1/60 of an Equestrian gallon) and a multiple, the Equestrian barrel (60 Equestrian gallons).

### Time

The basic unit of time is the second. A second is 1/60th of a minute, a minute is 1/60th of an hour and an hour is 1/24th of a day.

A moon is equivalent to 29.5 days and a sun is equivalent to 365.25 days.

Equestria uses the Selenial Calendar, which pegs the latest Canterlot eclipse as day 1 of the year 1001. Previously, the Helial Calendar was used, which pegged the day 1 of the year 1 at the coronation of Princess Celestia.

### Speed

For speed, paces per second or walks per hour are common measurements.

### Weight

The bit (b) is the standard unit of weight.

It is defined as the weight of a gold bit made of pure gold, which is 1/4th of a royal hoof in diameter and 1/16th of a royal hoof in width.

### Force

The standard unit of force is the bit of force, which is equivalent to the force of gravity on a bit of weight in Equus at sea level.

### Energy

The standard unit of energy is the Equestrian calorie, which is equivalent to applying a force of a bit over a standard pace.

### Power

The standard unit of energy is the dray, which is equivalent to an Equestrian calorie per second.

### Charge

The basic unit of electric charge is the silver deposition (sD), which is the charge needed for a silver nitrate solution to deposit the amount of silver in a silver bit made of pure silver.

As a silver deposition is an unwieldily large unit, it's more common to use a subdivision, usually the division of this unit by sixty cubed.

### Tension

The basic unit of tension is the bolt (B), equivalent to an Equestrian calorie per the division of a silver deposition by sixty cubed.

### Current

The basic unit of current is the spark (S), equivalent to the division of a silver deposition by sixty cubed per second.

## Qilinia

Qilinia uses the imperial hoof (iH), whose length is pegged to the royal hoof.

## Griffonstone

Griffons use claws (c), which are equivalent to the length of a fully extended Griffon claw between the furthest tips of the talons. A claw is approximately 7/3rds of a standard hoof or 7/4ths of a royal hoof.

## Yakyakistan

Yakyakistan uses hooves. The yak hoof (yH) isn't standardized, but Yak hooves are similar in length to a Pony hoof so a measurement in yak hooves usually doesn't need conversion to standard hooves.

## Changeling Lands

Changeling hives traditionally used the hoof of their queen as a measurement unit. These units became standardized among hives as time passed and remained in use even as some hives lost their queens.

A changeling royal hoof (cH) is roughly 11/8ths of a pony standard hoof.

## Conversion tables

### Length

To standard hooves

From standard hooves