# Volume Calculator

Use to find the amount of silicone rubber and casting resin needed.

#### Mold Box Volume - Rectangular

in.in.

in.

#### Part Volume

in.in.

in.

#### Net Volume

Box Volume (in.³)– Part Volume (in.³)

= Net Volume (in.³)

#### Mold Box Volume - Cylindrical

in.in.

#### Part Volume

in.in.

#### Net Volume

Cylinder Volume (in.³)- Part Volume (in.³)

= Net Volume (in.³)

#### Silicone Rubber Needed:

### grams

### pounds

#### Casting Resin Needed:

### fl. oz.

### gallons

### Amount of RTV Needed for Making a Silicone Rubber Mold

*Note: There are 21 grams per cubic inch of Silicone Rubber.*

There are 453 grams in 1lb.

##### Formula for a Square/Rectangle Mold: Length x Width x Height

**Example:** You have a mold box that needs to be filled up 9" x 4" x 2" = 72 cubic inches in order to completly cover your original/part.

Now using the same formula subtract the cubic inches (volume) of your part.

**Example:** Your part is 8" x 3.5" x 1.5" = 42 cubic inches.

Then you would take 72 - 42 to give you a total of 30 cubic inches.

30 cubic inches x 21 grams per cubic inch = 630 grams of RTV needed.

And then if you want to calculate that into lbs. take 630 divided by 453 grams per lb. = 1.39 lbs. of RTV.

##### Formula for a Round Mold: Pi x Radius (squared) x Height

**Example:** The diameter of a mold is 4" (the radius would then be half of that being 2") and the height is 3".

**So this is what it would look like:**

2" x 2" (radius squared) x 3.14 (pi) x 3 (height) = 37.68 cubic inches.

Now using the same formula subtract the cubic inches of your part.

**Example:** The part is 3.5" diameter (1.75" radius) by 2.75" high.

**So this is what it would look like:**

1.75" x 1.75" (radius squared) x 3.14 (pi) x 2.75" (height) = 26.45 cubic inches.

Then you would take 37.68 - 26.45 to give you a total of 11.23 cubic inches.

11.23 cubic inches x 21 grams per cubic inch = 236 grams of RTV needed.

And then if you want to calculate that into lbs. take 236 divided by 453 grams per lb. = .52 lbs. of RTV.

### Amount of Resin Needed to Cast a Part

*Note: There is .554 ounces in 1 cubic inch of Alumilite Resin.*

##### Formula for a Square/Rectangular Piece: Length x Width x Height

**Example:** If your piece is 3" x 4" x 2" = 24 cubic inches. Take 24 cubic inches x .554 ounces per cubic inch = 13.25 ounces.

**Formula for a Round Piece:** Pi x Radius (squared) x Height.

Use the same formula as the RTV round mold (section 1) to calculate resin needed. Then multiply that by .554 ounces per cubic inch to determine ounces needed.