How Much Does a Cast Iron Tub Weigh

The best types of bathtubs are made of cast iron owing to its many advantages.

Having been popularized in the 1800s by royal families around the globe, cast iron tubs are still going strong to this day given their great looks, high heat retention levels, and durability. With heat retention, your electricity bill will not be high each time you relax in the bathtub.

The average cast iron tub weighs roughly 250 to 500 pounds. This depends also on its shape and size.

Knowing the weight of cast iron bathtubs is vital in determining whether your floor is strong enough to support the bathtub upstairs. Even with that, you need to factor in the weight of the water.

Given that the weight of water is 8.34 pounds a gallon, you need to find the total weight of water when the bathtub is full then add it to the weight of the bathtub as shall be shown in the following sections.

Types Of Cast Iron Bathtubs And Their Weights

The three main types of cast iron tubs, their dimensions and weights are as shown below:


These have a typical length of 60 to 75 inches with a capacity of about 82 gallons.

Their weights are from 400 pounds and upwards. The weight of water will be (82*8.34=) 683.88 pounds. The total weight will be (400+683.88=) 1083.88 pounds.


These bathtubs often measure about 60 inches in length with a 32-gallon capacity.

Their weight is about 320 pounds. The weight of water will be (32*8.34=) 266.88 pounds. The total weight will be (320+266.88=) 586.88 pounds.


These are the smallest of the lot with a length of about 50 inches and a 32-gallon water capacity and 250-pound weight.

The weight of water will be (32*8.34=) 266.88 pounds. The total weight will be (250+266.88=) 516.88 pounds.

To be on the safe side, ensure your floor supports the total weight of the water and bathtub plus 300 more pounds. The 300 extra pounds are provision for the size of a big human being (the average human weighs 137 pounds).

Luckily, today’s buildings are built with a specific live load of certain pounds per square foot. This ensures that even the heaviest person using the heaviest bathtub will not have an issue.

Your Bathtub And The Floor

Your Bathtub and The Floor

The fact that you are checking the weight of your cast iron tub means that you need to support or carry it.

It is advisable that your house can handle the weight of the items you will be buying. Residential building codes dictate the weight that can be supported by the floor with the United States having a maximum live load of 40 pounds per square foot.

To obtain the maximum weight supported by your floor, multiply the live load by the area of the floor.

For example, if you live in the United States and your floor is 8 by 10 feet, the weight your floor can support is (8*10*40=) 3200 pounds. The live loads for other countries can be found here for reference.

However, before you install the bathtub in your house, ensure the live load of the floor is checked by an expert first.

The Weights of Other Bathtub Types

Perhaps your bathtub is not made of cast iron, and you are wondering how much it weighs. There are good bathtubs made of other materials such as fiberglass, steel, acrylic, and others.

While these materials make good bathtubs, cast iron beats them in that they are poor heat retainers, less durable, and less stable (due to less weight).

Their weights are as follows:

  • Fiberglass: a bathtub made of fiberglass and measuring 60 inches will weigh in at about 80 pounds.
  • Acrylic: a 60-inch bathtub made of acrylic will weigh in at about 110 pounds.
  • Steel: for steel, a bathtub measuring 60 inches will weigh in at 75 pounds. Steel will often be covered in enamel or porcelain to prevent rusting. These materials are part of the weight.

With this information, you will be able to make the right decision concerning the bathtub of your choice. Or you can opt for a shower instead.