When comparing Fitbit Zip vs Fitbit Charge, the Slant community recommends Fitbit Zip for most people. In the question“What are the best fitness trackers?” Fitbit Zip is ranked 7th while Fitbit Charge is ranked 26th. The most important reason people chose Fitbit Zip is:
The Zip keeps you motivated through friendly competition. Along with giving you a rank among your friends, you can also cheer them on or taunt them.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Social component to help keep you motivated
The Zip keeps you motivated through friendly competition. Along with giving you a rank among your friends, you can also cheer them on or taunt them.
Pro Easy to hide under your clothes
The Fitbit Zip fitness tracker is very small, so you can easily wear it somewhere that it will be hidden (belt, pocket, bra strap, etc.). Unlike most trackers which have wrist bands, you don't have to worry about trying to make it blend in with what you're wearing.
Pro Fitbit app lets you track a variety of health-related stats
The app doesn't only display the stats from your device, it also lets you track a variety of different health-related stats by entering them manually. You can log your food for the day, how you slept, activity, weight, and more.
Pro Automatic synching that's easy to setup
The Fitbit Zip fitness tracker wirelessly syncs with both PC and smartphones via the Fitbit app. After getting it set up you don't even think about syncing, it's just automatic.
Pro Integrates social features
Users can see their friends' activity, compete one-on-one, and earn badges.

Pro Battery lasts a week or more on a single charge
The battery is rated for 7 days, and has been tested up to 9 days by reviewers.

Pro Multifunction display
In addition to fitness metrics, a Fitbit Charge synced with a phone will display time and caller ID.

Pro Smart alarm wakes you up at the optimal time
The Charge tracks sleep cycles, and its alarm can be configured to take this into account, attempting to select an optimal wake time.
Cons
Con Lacking many of the features that fitness trackers often offer
The Fitbit Zip only tracks distance, steps, and calories burned. It's basically a pedometer with a smart tracking platform you can use for manually tracking the rest of your day. It can't tell you stairs climbed or heart rate, and there is no alarm, sleep tracking, or GPS.
Con Issues with the battery not working
The contacts in the device are very sensitive. If you don't place the battery in just right, it will only work for a short period of time before the battery needs to be readjusted or replaced.
Even when following instructions provided by the company, some people report that still can't get it working properly. The battery may end up lasting days instead of the promised 4-6 months.
You can see how to properly change the battery here.
Con Easy to lose
The tiny size of the Fitbit Zip makes it very easy to lose track of.
Rather than a wrist watch like many other trackers, it only has a slide on clip. The clip is fairly secure for normal activity, but you may knock the tracker off without realizing it.
Con Lacks a rechargeable battery
The Fitbit Zip fitness tracker runs on a 3-volt lithium-ion battery that lasts between 4 and 6 months. It requires getting a new battery every time it runs out of charge.
Con Flimsy two-prong wrist strap
Fitbit was expected to update their wrist strap with the Charge, but an upgraded buckle can only be purchased with Charge HR.
