The sandbox calculator is everything you should be looking for when picking a sand play tool! It's not just about calculating the volume of the sandbox — we'll tell you exactly how much sand to fill a sandbox is enough, all according to your child's age. 🏖️

Keep up with us to find out how many bags of sand for a sandbox is a bare minimum, what the density of sand is, and discover all the math that stands behind our sandbox calculator.

Playing in sand can bring a lot of joy — check what you can use it for when you no longer need it: paver sand tool! 👷

How to adjust the amount of sand to the age of the child?

It would be best if you chose the depth of sand in the sandbox depending on the age of your child. Here's how to do it!

AgeRecommended depth
Infant, 1-2 years old2.5 in (6.4 cm)
Toddler, 2-3 years old3 in (7.6 cm)
Preschooler, 3-5 years old5 in (12.7 cm)
Gradeschooler, 5-12 years old9 in (22.9 cm)

Remember to consider your own kid's preferences!

How to use the sandbox calculator?

It's even easier than it seems! You'll only need 3 or 4 steps, depending on the shape of a sandbox!

  1. Choose the shape of the sandbox. You can choose between:

    • Round;
    • 4-sided (rectangular or square);
    • 5-sided (pentagonal);
    • 6-sided (hexagonal); or
    • Custom — the sandbox area of your choice.
  2. Find the age of your child in a list.

    The depth of the sandbox depends on the age of a child. You may also choose the custom depth of your choice.

  3. Enter the dimensions of your sandbox.

    Depending on a shape of a sandbox chosen, the play sand calculator will ask you either about its length & width, radius, or one side.

  4. Your results are already here. 🍾

Here's your answer for "calculate how much sand I need for sandbox", given in a unit of your choice.

You've put the sandbox sand calculator to a good use — do you already know how to construct the box itself? Let us inspire you with the
brick calculator and the board foot tool! 🧱

How to calculate the volume of a round sandbox? ⚫

That's an unusual sandbox! We can compute its volume easily, using the equation taken from our sandbox calculator:

Round sandbox volume = π * r2 * Depth


  • π — Equal to around 3.14,
  • r — Radius of a circle; 2 times the radius is the diameter,
  • Depth — Depends on the age of a child, see the sandbox age table.
💡 In order to calculate how much sand for a sandbox we need, we ought to know the density of sand. It's equal to 0.057874 lb / cubic inch (1601.9 kg/m³)

For more information on the round calculations, visit the area of a circle calculator. 📚

How to calculate the volume of a 4-sided sandbox? ⬛

Is your sandbox rectangular or square? No problem at all; our sandbox calculator's prepared for all the possible options!

To calculate it all by yourself, use the following equations:

Rectangular sandbox volume = Length * Width * Depth; or

Square sandbox volume = Side * Side * Depth


  • Depth depends on the age of a child.

Still hungry for 4-sided calculations? Try:

How to calculate the volume of a pentagonal (5-sided) sandbox?

That's the tough one! Let's take up the challenge:

  1. Measure one of the sides of the sandbox.

  2. Use the equation taken from the sandbox sand calculator:

    5-sided sandbox volume = (Side² * √(25 + 10√5) / 4) * Depth

Depth depends on the age of a child. See the paragraph at the top of the page for more details.

The pentagons are not as scary as it seems! Check everything about them in the pentagon calculator. ⬠

How to calculate the volume of a hexagonal (6-sided) sandbox?

This problem is a little bit more complicated — but just follow these steps:

  1. Measure one of the sides of a hexagon.

  2. Use the equation, as featured in our play sand calculator:

    6-sided sandbox volume = (3 * √3/2 * Side²) * Depth

Depth depends on the age of a child. See the paragraph at the top of the page for more details.

Still want to know more about hexagons? Visit the hexagon calculator. ⬡

How much sand to fill a sandbox?

  1. In order to calculate the amount of sand, we first need to know the sand density that matches the unit you used when computing the volume of a sandbox.

    0.057874 lb/cu in, or 100.0063 lb/cu ft, or 1601.9 kg/m³, 1.6 g/cm³

  2. And here comes the easy step — multiply the volume of your sandbox with the density of sand. For instance:

    Amount of sand (lbs) = Volume of a sandbox (cu in) * 0.057874 lb/cu in

  3. Hey, you're already done! Go ahead and make yourself a nice cup of tea. ☕

How many bags of sand for a sandbox?

Our calculations are based on a following fact:

💡 A standard 14" x 26" (36 by 66 cm) sandbag or 17" x 32" (43 by 81 cm) sandbag can hold around 50 pounds of sand.

In order to calculate the number of bags for your sandbox, use the following formula:

No. of bags = Amount fo sand needed (lb) / 50

Yay, that definitely was an easy job! 🤓

Łucja Zaborowska, MD, PhD candidate
Shape choice
circle with radius marked

Child's age
1-2 years old (infant)
Radius (r)
Sand needed
No. of sandbags needed
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