How Much Water Does a Bathtub Hold?

Have you ever wondered exactly how much water it takes to fill up a bathtub? With tubs ranging in size from small apartment tubs to large corner garden tubs, the amount of water required can vary dramatically.

Determining the water capacity of your tub depends on its dimensions and typical fill level. A standard 5 foot tub holds 35-45 gallons when full, but most baths only require 20-40 gallons. Oversized and extra-deep soaker tubs can hold over 100 gallons fully filled. Compare this to the average shower using just 10-25 gallons per use.

Read on to learn key factors in calculating your tub’s capacity and typical water usage.

How Much Water Does a Bathtub Hold?

Determining how much water a bathtub holds depends on a few key factors, primarily the dimensions of the tub.

Bathtubs come in many shapes and sizes, from small apartment tubs to large soaker tubs. The capacity can range from 30 gallons for a small tub to over 100 gallons for an extra-large soaking tub.

Here’s an overview of the main considerations for calculating bathtub water capacity.

Standard Bathtub Sizes

The most common bathtub size in the US is 60 x 32 inches (5 feet long and 2.5 feet wide). This is the typical size for most families.

For this standard size, the average water capacity is:

30-50 gallons for a regular bathtub depth of 14-17 inches
60-80 gallons for a deeper soaking tub depth of 18-20 inches

Some key factors that affect the capacity are the shape of the tub (oval tubs hold more) and whether it has an anti-slip surface or texture that displaces water. Overall, most regular tubs of this size hold 35-45 gallons when full.

Small Bathtubs

Compact and apartment-sized tubs are often 48-54 inches long but retain a standard width of 32 inches. These smaller tubs have a capacity of:

25-35 gallons for a typical depth of 14-17 inches

The shortened length reduces overall capacity. A small 50 x 32 inch tub will hold about 30-40 gallons filled. Short soaking tubs around 54 x 32 inches can hold 35-50 gallons.

Large & Extra-Large Bathtubs

For larger tubs, such as corner garden tubs or soaker tubs, the capacity increases. Some examples:

66 x 32 inch tub – 45-55 gallons
72 x 36 inch tub – 60-80 gallons
60 x 42 inch oval tub – 80-100 gallons

Extra-large tubs designed for two people or more can exceed 100 gallons easily. Always check the product specs for the capacity of oversized tubs.

Calculating Bathtub Gallon Capacity

You can calculate the approximate water capacity of any bathtub by multiplying length x width x depth.

For example, a 60 x 32 inch tub with a depth of 14 inches would be:

60 in x 32 in x 14 in = 27,200 in3

Convert the cubic inches to gallons by dividing by 231 (the number of cubic inches in a US gallon):

27,200 in3 / 231 in3/gallon = 117 gallons

So for this example tub, the total capacity is around 117 gallons when full.

Use this method to estimate how much water your specific tub holds. Measure each dimension in inches – length, width and typical depth when filled. Multiply together, then divide by 231 to convert to gallons.

Factors That Affect Water Level

When estimating the actual amount of water needed to fill a tub, there are some additional factors to consider:

Tub shape – Curved tubs and oval tubs require more water than rectangular tubs
Anti-slip surface – Textured tub floors displace water so more is needed to cover the surface
Water depth – Filling to different depths requires more or less water
Tub materials – Porcelain enameled steel tubs retain heat better than acrylic or fiberglass
Presence of a tub filler – Faucet fillers require less water than standing fillers

To optimize your bath volume, choose an oval or curved tub with smooth surfaces, and fill to a moderate depth. Tubs with textured or anti-slip floors may require 5-10 more gallons to account for displacement.

Standard Bathtub Fill Volumes

While every tub has a maximum capacity, most people fill their tubs to a comfortable depth using far less water. Here are some typical fill volumes for common tub uses:

Bath for one – 25-35 gallons
Soaking bath – 35-50 gallons
Two-person bath – 40-60+ gallons

The average bathtub faucet flow rate is 1.5 gallons per minute on low pressure settings. So a typical 30 gallon bath would take around 20 minutes to fill completely.

Water Usage Factors

When estimating your overall home water usage, also consider:

Number of baths per week – The more frequent baths, the more water used
Showering vs. bathing – Showering generally uses less water than a bath
Bathing children – More frequent kid baths increases hot water requirements
Temperature settings – Heating water accounts for up to 25% of home energy costs

Using a water-efficient showerhead (under 2.5 gallons per minute flow rate) will conserve hot water. Also consider installing a tankless water heater for greater efficiency.

Here is a table summarizing key bathtub sizes and water capacities:

Tub Type	Typical Dimensions	Full Capacity	Typical Fill Volume
Standard tub	60″ x 32″ x 14″	35-45 gallons	25-40 gallons
Small tub	54″ x 32″ x 14″	25-35 gallons	20-30 gallons
Large tub	66″ x 32″ x 18″	45-60 gallons	30-50 gallons
Extra-large tub	72″ x 42″ x 20″	80-100+ gallons	50-80 gallons
Jacuzzi tub	70″ x 70″ x 22″	150-200+ gallons	80-150 gallons

How Much Water Does a Standard Bathtub Hold?

For a standard bathtub with dimensions of 60 x 32 inches (5 x 2.5 feet), the average water capacity is:

35-45 gallons for a regular depth of 14-17 inches
60-80 gallons for a extra deep soaker tub of 18-20 inches

This accounts for the most common US bathtub sizes. However, the actual amount of water used for a typical bath is less than maximum capacity.

Key Factors Affecting Water Volume

Tub shape – Curved tubs require several more gallons than rectangular tubs
Floor surface – Anti-slip textured floors displace water so more is needed to cover
Filling depth – More water is required to fill a deeper bathing level
Tub material – Porcelain steel retains heat better than acrylic or fiberglass

Typical Fill Volumes

While an average tub holds 35-45 gallons when completely full, most people do not fill tubs to maximum depth.

Typical fill volumes for common bathing uses are:

Bath for one – 25-35 gallons
Soaking bath – 35-50 gallons
Two-person bath – 40-60+ gallons

The average tub faucet has a flow rate of 1.5 gpm (gallons per minute) on low pressure. So filling a 30 gallon bath takes around 20 minutes.

Factors That Increase Water Usage

When estimating total home water consumption, also consider:

Frequency of baths per week – More baths means more water used
Comparing showers vs. baths – Showers generally use less water
Bathing children – Frequent kids’ baths increases hot water needs
Temperature settings – Heating water accounts for up to 25% of home energy costs

Using water-efficient fixtures can help conserve hot water and lower your energy bills.

How Much Water Does a Large Bathtub Hold?

Larger and deeper bathtubs can hold considerably more water than standard tubs. Some examples of oversize tub capacities:

Large Tubs

66 x 32 inch tub – 45-55 gallons
72 x 36 inch tub – 60-80 gallons
60 x 42 inch oval tub – 80-100 gallons

Extra-Large Tubs

60 x 60 inch double tub – 90-120 gallons
72 x 42 inch corner tub – 100-140 gallons
70 x 70 inch corner Jacuzzi® – 150-200+ gallons

Factors Affecting Water Volume

Key considerations for large tub capacity:

Tub shape – Curved and oval tubs require several more gallons than square tubs
Tub depth – Deeper soaking tubs hold considerably more water
Tub length – Longer tubs have greater capacity
Special features – Jets, bubbles, and other features displace water

Typical Fill Volumes

While extra-large tubs hold over 100 gallons if filled completely, typical fill volumes are:

Soaking bath – 50-70 gallons
Double tub bath – 60-90 gallons
Jacuzzi tub – 80-150 gallons

Filling these tubs requires longer faucet run times. For example, filling a 100 gallon soaking tub could take over an hour at average faucet flow rates.

How Much Water Does a Bathtub Use per Bath?

While bathtub capacity ranges widely, actual water usage depends on your specific bathing habits:

Key Factors in Water Use

Number of baths per week/month
Typical fill volume used
Depth filled to for bathing
Time spent in the bath
Number of people per bath

The more frequently you bathe and the more water used per bath, the higher your overall hot water usage.

Average Water Usage Estimates

Standard tub – 25-40 gallons per bath
Large tub – 30-60 gallons per bath
Soaking tub – 40-80 gallons per bath

The average household takes 1-2 baths per week. So estimate:

1 person – 25-80 gallons weekly
2 person home – 50-160 gallons weekly

This translates to 100-300 gallons of water for bathing per month.

Compare this to the average shower using 10-25 gallons per shower. Over a month, showering uses 30-75% less water than weekly baths.

Saving Water

To conserve hot water when bathing:

Take showers instead of baths when possible
Install a low-flow showerhead (under 2.5 gpm)
Only fill tub partially instead of full capacity
Reuse bath water for washing or irrigation
Consider installing a tankless water heater

How Much Water Does a Bathtub Hold Compared to a Swimming Pool?

While bathtubs hold anywhere from 30-200 gallons, swimming pools hold tens of thousands of gallons in comparison.

Key Differences

Purpose – Bathtubs are for bathing, pools are for swimming and recreation
Size – Bathtubs are only several feet long, pools can be over 15 yards long
Depth – Tubs average 2-3 feet deep, pools are up to 10 feet deep
Capacity – Tubs hold dozens of gallons, pools hold thousands or more

Here’s how average bathtub and swimming pool water capacities compare:

Small 50 gallon tub vs. 10,000 gallon pool
Large 100 gallon tub vs. 15,000 gallon pool
200 gallon Jacuzzi® tub vs. 30-50,000 gallon pool

Clearly, residential pools require enormously more water than bathtubs – up to 250 times more even for small pools.

Usage Factors

Pool size, frequency of use, evaporation rates, and local climate all affect water consumption. Pools in hot climates can lose thousands of gallons per month through evaporation.

While pools use far more total water, baths require heating all water used. Pool heating is less energy intensive by comparison.

Conservation Tips

Save water around pools by:

Installing a pool cover to minimize evaporation
Maintaining proper water levels to avoid unnecessary refilling
Ensuring water recirculates properly through filtration systems
Checking for and repairing any cracks or leaks promptly

Proper ongoing pool maintenance is key to minimizing water waste.

FAQ About Bathtub Water Capacity

How Many Gallons Does It Take To Fill A Bathtub?

Most regular tubs take 20-30 gallons to fill for a typical bath. Larger and deeper tubs require 35-50+ gallons. Actual usage depends on fill volume and bathing frequency.

How Do You Calculate The Capacity Of A Bathtub?

Measure the tub’s length, width, and typical depth in inches when filled. Multiply L x W x D to get cubic inches, then divide by 231 to convert to gallons.

How Much Water Does A Jacuzzi Tub Hold?

Jacuzzi tubs range from small 60-inch models holding 60-80 gallons up to large 70+ inch tubs holding 150-200+ gallons. Their extra jets and features displace more water.

How Many Gallons Of Water Are In A Kid’s Bath?

Kid’s baths require around 10-15 gallons of water for younger children in smaller tubs. Older kids in standard tubs use 15-25 gallons.

Should I Take Baths Or Showers To Save Water?

Showers generally use less water than baths – 10-25 gallons per shower versus 20-40+ gallons per bath. To conserve, limit baths to 1-2 times per week max.

Final Thought

A standard bathtub holds 35-45 gallons but typical baths use just 20-40 gallons per use. Larger and deeper tubs can hold 80-150+ gallons fully filled.

Compare this to showers using 10-25 gallons. Know your specific tub size, filling habit, and usage frequency to best estimate your home’s bathtub water consumption.

How Much Water Does a Bathtub Hold?