With the changes in the luggage restrictions that affect the checked and the carry-on luggage for every flight, having your own scale will allow you to pre-weigh you luggage before getting to the airport.
The digital and the analog scales are the two available types on the market. The accuracy of the device is an important consideration, and you will find that the accuracy is greater on the digital model and so is the readability. Since price of the two types vary so little, it makes good sense to purchase the digital model.
You must remember to actually put the scale in your luggage before completing your packing, since you will be using it to measure any additional luggage you will choose to return with. Make sure that the scale is not too heavy to add any significant additional weight to your luggage. Also make sure that it will weigh up to and a little more than, the maximum weight you will normally travel with. If planning to use it for other purposes, you should purchase one with a higher weight limit.
Scale manufacturers usually make the devices available in units of pounds (lbs.) and kilograms (kg.). Getting these units in ounces (oz.) and in grams (gm.) is also possible. Having a carry case for the unit is convenient as with other digital devices, and be sure to select one that can be easily handled and read without much difficulty.
Several features are also available with some scales like a tape measure. This is very handy since you are able to measure the dimensions of the luggage. This will allow you to comply with the carry on dimension regulations. Other features that may be included are, LED flashlight, an alarm/timer and additional batteries.