The height you should fill a bathtub to is around 2/3 full as once you step into the bathtub it will cause the water to rise as you displace the water which can cause the water to spill over.
The amount of gallons that a 5 foot bathtub holds is roughly 80 gallons of water and smaller bathtubs hold around 40 gallons of water.
The amount of gallons of water it takes to fill a Jacuzzi bathtub is between 80 gallons to 120 gallons of water.
Smaller Jacuzzi bathtubs would use around 80 gallons of water and larger Jacuzzi bathtubs would use around 120 gallons of water.
A bath uses more water than a 20 minute shower especially if you use a low flow shower head.
With a low flow shower head your 20 minute shower will only use around 20 gallons of water or sometimes less and a bath uses around 30 to 40 gallons of water.
However if your shower head is a 2 gallon per minute shower head then it could use more water than a bath taking a 20 minute shower or could turn out to be the same.
A 10 minute shower with a low flow shower head is around 5 to 8 gallons of water and with a high flow shower head the 10 minute shower is between 17 gallons to 20 gallons of water.
An average shower uses between 17 gallons to 20 gallons of water depending on the flow of your shower head and the length of your shower.
I've read my water meter before a shower and after as hower and my shower uses 20 gallons in a 10 minute shower but my shower head is a 2 gallon per minute shower head.
If you have a 1 gallon per minute shower head or low flow shower head then you may only use 10 gallons of water in the 10 minute shower or 20 gallons in a 20 minute shower.
Showers mostly use less gallons of water than a bath if you take shower showers and use a low flow shower heads.
I love the pressure of my higher flow shower head even when I use more water.
We have plenty of water here so there's need to worry about conserving water.
An average bathtub or bath uses around 30 gallons of water.
Showers are also cleaner than baths as with a bath you sit in the filth and showers rinse all the germs away.
The average American shower uses 17.2 gallons (65.1 liters) of water and lasts for 8.2 minutes at average flow rate of 2.1 gallons per minute (gpm) (7.9 lpm).