How To Measure A Turtle

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how to measure a turtle

It’s critical to measure a turtle if he’s growing at the right rate, if he’s healthy or not, and also how big his enclosure should be.

A turtle’s measurement is taken as a straight line from the carapace’s front to its rear and this is called the straight carapace length.

The straight carapace length is done by constructing an imaginary line that passes through or above the turtle. You should avoid going along the carapace’s ridge since some species have highly domed surfaces, like musk turtles, that will give you false readings.

Consider it like putting bookends on both ends, then measuring the distance between them. The width of the bookend would be the turtle’s carapace.

When you’re measuring a baby turtle, make sure to use a soft tape measure or even a piece of string that has been measured against a ruler. Baby turtles will have a softer shell than adults and you don’t want to hurt them by using a hard measuring tape.

Turtle shells come in all sorts of shapes and sizes. Some turtles have long, narrow shells while others have stocky, round shells. The type of shell a turtle has is called the carapace.

Correct Shell Measurement

Measuring The Carapace Of The Turtle

If you strictly want to measure the carapace of the turtle you will need to take a soft measuring tape that will stretch from the bottom edge of the carapace up to the center of the carapace until the bottom edge. This will be the total length of the carapace.

The width of the carapace is taken at the widest part of the shell and goes the same way with the measuring tape from one end of the carapace across to the opposite edge.

RELATED READ: How Strong Is A Turtle Shell?

Measuring The Plastron Of The Turtle

The plastron is the underside of the turtle and it can be quite different in shape and size from the carapace. The plastron is generally flatter than the carapace and some turtles have a hinged plastron that allows them to completely close up their shell.

When measuring the plastron, you will again use a soft tape measure. Start at the end of the plastron where the turtles tail is located and stretch it up to the other side of the plastron where the turtles head is. This will be the total length of the plastron.

The width of the plastron is taken at the widest part and it is measured in the same way as the carapace width.

RELATED READ: How To Take Care Of A Turtle

Measuring The Shell’s Height

The position of the turtle’s lungs beneath its shell makes it difficult to put it on its back. If you must turn the turtle over for any size measurements, do so as soon as possible and carefully. You run the risk of harming your turtle if you leave it on its back for more than one minute at a time.

You’ll need a meter ruler and a straight flat stick that’s longer than the turtle’s carapace in width. Carefully flip your turtle onto its back and from this point on, move swiftly.

Along the hinge, place the straight flat stick across the plastron of the turtle with the level placed on top of it. After you’ve got both items together and level, stand up vertically using your meter ruler as a guide and measure the turtle’s height.

The hinge of the turtle’s shell usually corresponds to the plastron’s highest point, so be sure to measure from this area on the plastron.

RELATED READ: Turtle Shell Peeling

What Is The Weight Of A Turtle?

Over time, you may use the weight measurement of the turtle as a way to track your turtle’s growth development and health condition.

It is important to keep track of your turtle’s weight and maintain its body mass within 1% of its total size. These statistics will assist you in determining how much your turtle can safely shed versus what it has lost at each weigh-in.

You need a scaler and a bowl to measure the weight of a turtle. Place the turtle in the bowl and then put it on the scale. If you don’t have a scaler, you can use a postal or food scale. If you use a food scale, you will need to subtract the weight of the bowl from the total weight that is displayed on the scale.

The more motionless the turtle, the more accurate your weight measurements will be. If you see that your turtle is too active, place it upside down in a gentle matter and move as fast as you can after doing so.

RELATED READ: How Big do Red-Eared Slider Turtles Get?

How To Measure A Tortoise

Tortoises are measured in the same way as turtles.

Place the tortoise against a wall, with its shell touching the wall. Place the ruler along the length of the shell, in the middle.

Ensure that both the scute’s rear portion and the low end of the ruler are firmly pressed against the wall. Look straight down (at right angles to) where an appropriate marking on the ruler is over that scute.

Place your thumb on the measurement and hold it there as you lift the ruler to reveal the length.

RELATED READ: How to Set Up an Indoor Box Turtle Enclosure

How Do You Measure A Red-Eared Slider?

Red-eared sliders can be measured in the same way as any other turtles.

The only difference is that their carapace is much flatter than other turtles. This means that you will need to be more careful when measuring the turtle’s width.

Be sure to measure the width at the widest point of the carapace. The easiest way to do this is to measure from one side of the shell to the other.

If you are unable to get an accurate measurement from one side of the shell to the other, then you can measure the turtle’s length and width.

RELATED READ: Caring For Baby Red Eared Sliders

Can You Tell How Old A Turtle Is By Its Size?

growth rings

No, you cannot tell how old a turtle is by its size. You need to look at the growth rings on the shell to determine its age.

The growth rings are annual and they can be counted to determine the age of the turtle. The number of growth rings will tell you how many years the turtle has been alive.

The growth rings are not visible on young turtles and they become more visible as the turtle ages. There are growth rings on the carapace and on the plastron.

RELATED READ: How Much Does a Russian Tortoise Cost?


There are a few ways that you can measure a turtle.

  • You can use a meter ruler and a straight flat stick to measure the height of the turtle.
  • You can use a scaler and a bowl to measure the weight of the turtle.
  • You can use a ruler to measure the length and width of the turtle.
  • You can also use growth rings on the shell to measure the age of the turtle.

No matter which method you choose, be sure to be as accurate as possible for the best results.