Introduction: Trampoline, the wonder device is now very popular to the people. It is made by a piece of strong fabric fixed in a steel frame. There are numbers of metal coiled spring. It is fixed on steel legs in a certain height.
The users ride on the fabric and jump on it.When they fall on it after jumping, they bounced and rebounded back from the fabric for the action of the spring. So the fabric is called by bounce mat.
There are different shapes and sizes of Trampoline in the market. The sizes are different because the open area at the backyard of the users are different. The shapes also are made different according to the requirement of the users.
Different Shapes:
The different shapes are Round,Square,Rectangular etc. Octagonal Trampolines also available. The sizes of Round Trampolines from 8 ft. to 14 ft. are popular. For Rectangular Trampoline – 8 ft. X 12 ft size is the common size for a family. 9 ft X 14 ft. size is for the professionals, and the 10 ft. X 17 ft. size is the Olympic size. The Oval shape (in between Round and Rectangular) and the Octagonal shape are not so popular.
Round Trampolines:
The common sizes of ROUND Trampolines are as 8 ft, 10 ft, 12 ft. and 14 ft. The 8 ft. round Trampoline is for the users who have a small garden and can provide a smaller space for the Trampoline. It can be use by one kid who is smaller at a time. It is good for those who have a small space to provide for Trampoline. Again who have a small child and who want the cost to be in the lowest range can choice this specification of Trampoline. Above all it is safe only for one kid at a time. More than one kid at a time may be dangerous for them.

Image Credit: https://www.youtube.com/watch?v=K343T0zpwXg
The 10 ft. round Trampoline is also for the users who have a small garden and can provide a smaller space for the Trampoline. It can be used by one kid who is larger a bit at one time. It also not fit for more than one kid at a time which may be dangerous for them.
The 12 ft. round Trampoline is also called as medium size Trampoline. It is perfect in respect of size to accommodate in a small garden. Two smaller kids can jump and enjoy by riding on it at a time. But there is a risk for to larger kids use it at one time.
The 14 ft. round Trampoline is ideal for a family. In spite of it requires some big space in the garden it is more safe than the Trampoline with smaller sizes available in the market. Due to the larger landing space kids can jump on it safely and enjoy the bounce of it.
Rectangular Trampolines:
Now about the Rectangular Trampoline
The common sizes of rectangular Trampoline are 7 ft X 10 ft, 8 ft X 12 ft,9 ft X 14 ft and 10 ft X 17 ft. are available in the market. The smallest size of rectangular Trampoline (7 ft X 10 ft) is portable and the user can place it at the suitable area of the garden. Due to the smaller size the user can shift it to the another area in the backyard to use the former space for any other activities also. But there is some risk if two kids jump on it at a time. There may be a chance of collision or they can fall out of the Trampoline. Due to the total body weight of two kids the frame of the Trampoline may be damaged. But it is suitable for the lower budget.

Image Credit: https://www.youtube.com/watch?v=Q78WrD7Wm20
The Trampoline with the size of 8 ft X 12 ft. is very popular for the families. The bounce on it is also good. The kids love it for the right amount of bounce on it. It is also ideal for two kids jump on it at one time. It is also great for the young kids who are looking for being gymnast or a sports person for its bounce.
The trampoline with the size of 9 ft X 14 ft. is very effective for the families and for the professional gymnasts. In the family who are very conscious with their health or who need to loss their body weight can choice it. They can overcome the monotonous running, jogging or passing a long time at a gymnasium by the Trampoline workout. It has been observed that the loss of calories by jumping for just ten minutes on a Trampoline is equal to running for thirty minutes.
Other shapes of Trampolines:
The Oval shaped Trampoline also are not bad. It is like a hybrid of round and square Trampolines. It takes a little extra space than the round one. So if the users have plenty space in the garden then it is the favourite place of the kids. Almost all the area of the Trampoline is offered for jumping.

Image Credit: https://www.youtube.com/watch?v=5g5v6SCQfKo
The Square Trampolines are not very popular. But a Square Trampoline offers some extra jumping space than the round Trampolines.
The Octagonal Trampolines are not popular as the price of it more than the round and rectangular Trampolines because a few makers sale it in the market. But the bounce of it is better than the others.
So, before buying a Trampoline you have to think about the space you can provide for it.
Conclusion:
The number of users at a time is an important criteria to choice a Trampoline. The total body weight of the users at a time should be lower than the maximum capacity of the Trampoline. The durability of the Trampoline also to be checked. Above all the budget for it is to be fixed after determination of the requirements.
Lastly the 12 ft. round Trampoline is most suitable for two kids at a time. For the use of the whole family the 14 ft. or 15 ft. Round Trampoline can be good. It will take some larger space in the garden. For the people who can provide a lesser space then the 10 ft X 17 ft rectangular Trampoline is most suitable for a family.