If you are looking to get a sense of how long 4 inches is, comparing it to other objects that you can relate to will be helpful.
This comes in handy if you don’t have access to a measuring tape or ruler.
You can say that something is about 4 inches long but without actually measuring it or comparing it to something of the same size, you are just estimating.
How long is 4 inches?
4 inches is equal to 10.15 centimeters or 101.6 millimeters.
Here are some other items that are 4 inches long.
4 quarters
If you measure a USA 25 cent coin, you will see that it is exactly 1 inch in diameter.
The great thing about coins is they have to be an exact size so they work well for measuring.
Place 4 quarters together in a row and they will equal 4 inches long.
So if you want to compare something that is 4 inches long with another item, use 4 quarters.

Business envelope
The common business envelope is 4 inches wide and 9.5 inches long, so you can use the width of the envelope to compare it with another object that is 4 inches long.
You can also use the length of the envelope but it won’t be as accurate as 4 inches would be less than half of the size.

2 Golf tees
Golf tees are a great item to use when comparing the size of other items.
The standard-size golf tee is 2 inches long. Placing 2 of them together in a row would equal 4 inches long.

Toilet paper roll
Toilet paper rolls are not a common item to use for measuring, but it makes a great item to use for comparing size as most people are familiar with them.
Picturing a standard toilet paper roll will give you an idea of something that is 4 inches long.
They are actually 3.7 inches long if you want to be exact.

Men’s wallet
Although wallets are available in different sizes, it’s common for a men’s wallet to be around 4 inches in length.
If you have a folded wallet in your back pocket, it should be close to 4 inches in size which makes it a common and easy to use item to compare with something else of the same size.

2 Pink erasers
The common pink eraser like the ones you would see in schools and stationary stores, has a length of around 2 inches.
If you have 2 of these erasers and place them together, they would equal close to 4 inches long.

2 AA batteries
If you have an AA sized battery in your house, you can use it for measuring the length of another object.
The AA battery is 1.99 inches in length so placing 2 of them together will measure just about 4 inches long.
This length includes the button terminal of the battery.
