Estimating how long or tall a foot is usually isn’t too difficult, since it’s a length most people are familiar with. Nine inches, however, can be a bit more of a challenge.

Using common objects to relate to nine inches, however, can help you get an accurate estimate of just how tall that is.

## Smartphones

Smartphones vary in length and height, depending on the brand and model. However, many phones, including some iPhone versions, are about four and a half inches tall. This is half the length of nine inches.

Picture a smartphone, and then imagine doubling the height of the phone. By doing this, you can get an accurate estimate of how tall nine inches is.

## A United States Dollar Bill

In the United States, a bill note is two and a half inches tall and six inches long. Picture the length of a dollar bill. Six inches is two-thirds of nine inches, so by imagining a dollar bill and then picturing another half of a dollar bill right next to it, you can get a great idea of how tall or long nine inches is.

## A Thumb

Thumb size varies a good deal, but in general, an adult’s thumb is about one inch long. This is, of course, one-ninth the size of nine inches. Look at your thumb, and then picture eight more thumbs stacked on top of it. You can also move your thumb along a surface to mark out inches. Either way, you’ll be visualizing about how long nine inches is.

## A Crayon

Most new crayons are about three inches long. This is one third the length of nine inches. If you can picture three crayons laying end to end, you can picture how long nine inches is.

## A Ruler

A standard ruler is 12 inches or one foot long, so three-quarters of that length is nine inches. If you’re looking at or picturing a ruler, simply imagine three inches less than that, or take away the top one-quarter of the ruler, and you’ll have an accurate approximation of how tall nine inches is.

## A Standard Paper Sheet or Notebook

In the United States, standard printer paper is eight and a half by 11 inches in size. This makes it easy to estimate nine inches. The short side of the paper is only one-half inch shorter than nine inches, so it’s a great approximation. The longer side is only two inches longer, so if you can picture taking away two inches, you can visualize nine inches.

Most standard spiral notebooks, such as those used for school essays and notes, are also eight and a half by 11 inches in size.

## A Square Pillow

One of the most common sizes for square pillows, such as couch throw pillows or decorative bed pillows, is 18 by 18 inches. Eighteen inches is twice as long as nine inches. To estimate how tall nine inches is, simply look at or visualize a standard throw pillow and cut the size in half.

Even longer bed pillows often have a height of 18 inches at each side, so you can still visualize nine inches by picturing half of a pillow’s height.

## Dolls

Dolls can come in any size or shape, but there are some common standard measurements that are often universal, which help when it comes to buying doll clothes. One of the most common sizes for larger dolls is 18 inches.

These dolls are one and a half feet tall, which is exactly twice as tall as nine inches, so if you picture half the height of a larger doll, you can estimate how tall nine inches is.

Other standard doll sizes include eight and 10-inch dolls. Nine inches is 1.125 times the size of the shorter eight-inch doll, and the taller doll is nine-tenths the size of nine inches. Picturing dolls of this size make it simple to get an accurate estimate of how tall nine inches is since they’re both so close in size.

## A Lunch Plate

Like any dish, lunch plates can be found in a variety of shapes and sizes. However, most standard lunch plates have a diameter of nine inches. Picturing a lunch plate can give you a very accurate estimate of how long or tall nine inches is.

Smaller bread plates are usually about six inches in diameter, which is two-thirds of nine inches. This estimate also works for square plates, which are usually either nine by nine or six by six inches.

## A Standard Bike Tire

Bike tire sizes can vary slightly depending on the bike size and what the tire will be used for, but many bike tires have a diameter of 27 inches. This is three times the size of nine inches. If you can picture a bike tire, imagine the diameter, and then split that into thirds. Each third will be about nine inches long.