Small steps. Big impact.


Fitbits are being assembled


Front shot of packaging

Hi All,

So I’m happy to announce that the first production Fitbits are in the process of being assembled. You can see Unit #2 in its packaging above. We’ve also closed pre-orders.

It’s been a long journey to this point. However, we’re about 2 weeks behind where we’d like to be. A lot of reasons for that, some logistical (some of our testing equipment was frustratingly stuck in Indonesian customs for 3-4 days) and some of our own making. The biggest issue we have right now is assembly throughput; it takes about 600 seconds to assemble and test a Fitbit, which is really long. We’re working to get that time down, but in the meantime, this is what it means for our schedule:

The first 10% of orders will finish being assembled and ship from Singapore to the US on July 30/31. They will arrive in the US on Aug 3/4th. It takes 2-3 days for Fedex International Priority to deliver these and clear customs. We will open these up in our US warehouse and do one final set of testing and verification and to load them with the latest firmware. We currently have 19 firmware bugs, which is not too bad at this stage and which we will stamp out between now and then.

We will start shipping these first units to customers on the week of August 10th. I will make a post when they ship to the US, when they arrive in our warehouse and also comment on the status of our bug queue.

Fitbits will continue streaming into the US in weekly shipments. We expect the last 25% of the orders to be shipped to the US around Aug 21st and shipped to customers on Aug 25/26th. The website will be open to all when the first units start shipping.

In general, you should get a final confirmation email a few days before your Fitbit will ship, which will give you a chance to review your order and confirm or cancel.

We’re excited to get these out to you as soon as we can!

Again, it’s been a long journey to get to this point. Here’s some photos and videos that give you an idea of what’s going on what right now as the Fitbits are being assembled:

Another packaging shot and the display in action showing steps:

Diagonal shot of packaging Showing steps

Video of the circuit boards being assembled by an SMT machine:

A small set of our finished circuit boards:

Lot of finished circuit boards

Lot of chromed housings and Fitbits with its guts hanging out

Lots of chromed housings Guts are hanging out

Lots of partially assembled Fitbits

Lots of partially assembled Fitbits

A Fitbit being “welded’ together in a ultrasonic welding machine. Ultrasonic waves are used to melt the plastic together in very tightly sealed unit. This is a $30,000+ machine we are using.

Fitbit QA


Hi Everyone,

We’re still on track here.

The main thing that we’re focused on now is developing testing systems to test each Fitbit as it goes through the assembly process. There’s several steps to the testing process.

The first is testing circuit boards. The Fitbit has 3 circuit boards. 2 are in the wearable Fitbit and 1 is in the wireless base station. After each circuit board is assembled, it is placed into a test fixture. One of our actual test fixtures is show below:


An operator places the circuit board into the fixture and then closes the lid on top of the board. The fixture contains many metal pins which make contact with special areas of the board. When the lid is closed, these pins make firm contact. Through these pins, we’re able to run tests which exercise various parts of the board automatically. Here’s a closeup of the board after the fixture lid has been closed on top of it. The black rubber feet gently push the board onto the test pins:

Closeup of the test fixture making contact with a board

Basically, we want to ensure that the right components have been placed on the board, that all the components are connected properly and that there are no manufacturing defects such as electrical shorts. We also do some mechanical tests such as automatically pushing the button to make sure that it’s connected properly. Here’s a solenoid switch that when commanded, pushes a button on the circuit board:

Solenoid switch to auto push buttons

2 of the boards are also connected by a cable, so we also do tests to make sure that the cable has been connected properly. Here’s an overhead shot of a test fixture that tests the cable connections. You can see the yellow cable drooping between 2 of the boards:

Testing the cable connections

Here’s some shots of the overall test fixtures:

Overall fixture

Fixtures in the lab

Once the circuit boards have passed testing, they are assembled in the Fitbit case or enclosure. Once enclosed we do another series of tests to ensure that

1. The enclosure process has not damaged the boards or the cable
2. The charging contacts and the USB cable have been properly soldered

We plug the Fitbit into its charger both ways to test proper charging contact connectivity and also connect the base station to a PC to make sure that the USB cable has been soldered properly and that the PC can communicate with the radio inside. We then do a series of special button presses on the Fitbit to put into a self-test mode, which does a final exercise of its functionality, including lighting up the display, checking components, etc.

In short, all this is to ensure that the Fitbits will be working well when they arrive on your doorstep.

FYI, 4 of our team are also flying to Singapore early Wednesday morning to start the assembly process. I’ll keep you posted on that.

Fitbit Website


In parallel to the Fitbit device, we’re working on the website. We expect to open this up to pre-order customers pretty soon. Here’s a couple sneak peek screen shots of our development. When we’re ready to open the beta of the website up, we’ll make a blog post and any volunteers can sign up by making a comment on that post.


We’re also busy polishing and further validating the software running on the Fitbit device itself. Here’s an older movie of the Fitbit in action when we were just testing basic functionality. You won’t see the button on the Fitbit here b/c when we shot the video, we were in middle of testing the tactile feel of different buttons. You can see the step counter iterating through 10 steps and see the screen in action here:

In terms of shipping, I still don’t have a concrete date other than late spring/early summer. I know you guys are still waiting, patiently. All I can say for now is that we’re getting closer. I’m anxious myself as I want to get the date out there and get my own stress levels down. :)

Support and Orders


Hi all,

Just a friendly reminder. If you have any order inquiries, like changing your address or card number, please send them to, rather than posting a comment to this blog. You’ll get a much faster response that way and it can be tracked. We want to make sure  you get a prompt answer.

thanks all

Fitbit Packaging


One of the things we’re trying to figure out as we get closer to shipping is the packaging. Originally, the goal of the packaging was to support the Fitbit in an purely online retail environment only. That gave our designers the leeway to design packaging without having to include a lot of the marketing copy that you see slapped over typical brick and mortar packaging.

Here were a few of the early concepts:

basic_box jewel_box

We thought the second “jewel box” concept would provide a great out of box experience for people who bought the Fitbit online and we went pretty far down the path of designing and prototyping the packaging:


However, as we started to get interest from brick and mortar retailers, we realized the packaging had some problems in the retail environment.

One, there was no way for curious people to see the product before they bought it and we didn’t think a single photo on the packaging would suffice. However, we didn’t want to do a typical clear “blister” pack which we felt looked cheap and was extremely difficult to open, at least for people not named Edward Scissorhands.

Secondly, the shape of the box was not ideal. Due to its long narrow shape, we felt when people took it off the shelf to look at it and then placed the box back on the shelf, they would tend to place the box on its back rather than on its narrow bottom. Also, due to the box’s 8″ long landscape orientation, it was not great for pegging onto a pegboard.

So we set out to solve these problems with another round of packaging design. We played around with a few concepts that we felt addressed the need for people to see the actual product, had shapes that promoted “correct” placement on shelves and also was peggable:


Our prime candidate currently is the concept below:


A brief look into how the Fitbit algorithms work


Again, I apologize for the infrequency of these blog posts. I’m a procrastinator when it comes to writing these things, which is bad.  A commenter suggested in a previous post that we make shorter more frequent updates rather than really long infrequent updates, which is what I’ll try to do in the future.

That said, you’re stuck with a long post this time around :)

On shipping…The bad news is that I still can’t give out a concrete date, yet. The good news is that we’ve resolved the problems around charging, which had been holding us up. I hope to have a firm shipping date soon. We’re waiting for one last round of prototypes to confirm our design and to tune a few last things. You’ve already been waiting patiently and the last thing we’d want to do is ship out anything that isn’t worthy of your wait. Rest assured, my team and I are singularly focused on getting the Fitbit out the door in a high quality way. I get enough queries from friends and relatives constantly asking when we’re shipping. :)

We’re also steadily working on the website. We hope to release a preview of that before the Fitbit ships so that you can get familiar with the interface.

We’ve also had a bunch of questions about the algorithms behind the Fitbit, so let me talk about that. The Fitbit’s primary method of collecting data is an accelerometer. Its accelerometer constantly measures the acceleration of your body and algorithms convert this raw data into useful information about your daily life, such as calories burned, steps, distance and sleep quality.

How do we develop these algorithms? Our approach is that we have test subjects wear the Fitbit while also wearing a device that produces a “truth” value. For calories, this “truth” device might be something like a Parvo Medics TrueOne 2400 or a Cosmed K4b2. You’d look really stylish wearing one of these:


These devices measure the gas composition of your breath, which is a very accurate way of measuring calorie burn. By wearing this type of device and the Fitbit at the same time, equations/algorithms can be developed that attempt to accurately convert the raw data collected by the Fitbit into the calorie numbers reported by the “truth” device.

Developing these algorithms take a lot of experimentation and test data. Sometimes the algorithms you develop work very well in one case but completely fail in another. For instance, your algorithm might be really accurate for slow walking but starts to fall apart during running. A lot of our research is finding algorithms that work reasonably well across a lot of different scenarios.

Here’s a recent result from a calorie measurement test we ran on a treadmill. RevB is the 2nd hardware revision of the Fitbit. The light grey line is what the treadmill showed for calories burned. The black line is what the Parvo TrueOne 2400 reported. The vertical lines are error bars which show the range of accuracy for the Parvo. As long as the Fitbit falls within those error bars, you can consider the results to be pretty good. As shown on this graph, the Fitbit measures calories reasonably well up to 8mph, where it starts to underreport calories slightly. This is an older result…we’ve improved things since then. The Fitbit’s software is also upgradeable over the wireless link, so as we constantly improve our algorithms, these improvements will be automatically uploaded to your Fitbit.

Calories burned on treadmill test

To develop the algorithms for step counting, we have test subjects wear the Fitbit while also carrying a click counter and clicking off steps. Sometimes we also have the test subject wear competitive devices so that we can measure how good we are against them. Here’s a photo of a typical setup. I’ve masked out the competitive devices to protect the innocent. (also, so they don’t get upset at us :) )

Device Test Belt

We really try to put the step counting algorithms through a lot of different (some crazy) scenarios:

This graph shows % step accuracy for climbing stairs quickly at 2 stairs/sec for the Fitbit vs 2 leading pedometers:

Fast stair climbing

You see that we’re fairly close to each other. We all average about ~89% accuracy.

An interesting thing happens when we start taking stairs a bit slower at 1 stair/sec:

Slow stair climbing

You see that the first pedometer really collapses to 20.5% accuracy, the 2nd pedometer degrades slightly and the Fitbit actually improves.

Here’s another graph which shows results from an 80 year old male with a cane walking 0.25miles around the block in 11 minutes (1.5mph). The Fitbit does pretty well here with 97.4% accuracy.

Results for an 80 year old male with cane

Most pedometers have trouble with people who take soft steps, which include a lot of elderly people. The cane here also can cause confusion, since the cane could look like a 3rd step in a stride. Even though these were some of the best pedometers on the market, they still had trouble in cases where you just weren’t simply walking smoothly and firmly in a straight line.

In general throughout our step counting tests, we found that the more expensive pedometers have better accuracy. If you ever get a free pedometer at work, just toss it out. Are you in the market to to buy a $5 or $10 pedometer? Don’t bother. Chances are you’ll be very disappointed.

Birth of the Fitbit


Sorry, it’s been a while since our last post. We’ve been tweaking the design to fix some of the issues I mentioned in the last post. I had been hoping to make one single post when all the issues had been resolved, but it’s been taking a while and so instead of keeping you in the dark further, here is the incremental update.

1. We’ve made some changes to improve the assembly time and process. Things can always be better on this front, but I think we’re closed to locked down on this aspect.

2. The button design was changed to make it easier to press. The pressing action is a lot less stiff, due to a softer rubber that we switched to and the shape of the button was altered to make it easier to press.

3. Charging. Ah, this has been the bane of our existence for the past few weeks. I think we’ve made some good progress, though. The stiffness of the contacts has been increased and this has helped in making sure that the contacts would no longer get deformed during the assembly contacts.

However, we still have not been able to get reliable contact between charging contacts. Here’s a couple photos to illustrate things:

Downward Charging Problem Side to Side Charging Problem

You can click through to see the larger pictures, but essentially, there is a lot of side to side movement and up and down movement once the Fitbit has been placed on the charging base station. This movement causes the contacts to potentially miss contact with each other and therefore no charging occurs.

It’s very possible that this misalignment is due to the imprecise nature of the process used to make the prototypes, since we don’t see this misalignment in the computer design files. Our prototypes are made by taking a block of plastic and using a computer driven drill to carve out the prototype. This drilling or “machining” process is a lot less precise than the final production process, which is injection molding: injecting molten plastic into steel molds.

However, just to be safe, we’ve made some more changes to prevent this issue and we are getting some more prototypes built to test things out, but I think it will be at least another 2 weeks before we know the answer for sure. In the meantime, we’ve ordered a lot of the individual electrical components and we expect those to arrive within 8 weeks.

I also wanted to give you a glimpse into the design process that got the Fitbit to this point. In the beginning, we commissioned a top industrial design firm to come up with design for the Fitbit. This firm has done a lot of groundbreaking products including the Palm Zire.

The first stage of the industrial design process was to come up with some basic shape concepts [click through to see larger image]:


Step 1 Shape Concepts

These are a subset of the shapes that we considered. This stage allowed our design firm and our team to come to an agreement about the usability and wearability of the Fitbit.

The second stage was to come up with some more developed pencil sketches of the basic shapes. This would allow us to hone in on the aesthetic direction of the Fitbit. Again, these are just a subset:


Step 2 Sketches


From these sketches, we selected 3 designs that would be further developed into computer renderings. Here’s the rendering of the winning design:


Fitbit Final Step Rendering


You can see the Fitbit’s final U shape evolve from the early shape concepts to the final rendering. You might also notice that the winning rendering is similar, but not quite the same as what our actual final product looks like. There are many reasons for this but the underlying thread is that engineering reality often causes the design to change. For instance, it was very difficult to fit all the components into the shape, so the Fitbit had to be thickened…the translucent display effect shown above was technically challenging to execute in a cost-effective and space-efficient manner, etc. In any case, I think both our industrial design and engineering team did a great job in converging on the actual final design that you see on our front page:

Fitbit with flower screen

Fitbit named 2009 CES Best of Innovations Honoree

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Every year, the CEA (Consumer Electronics Associations) names several companies as Design and Engineering award honorees. The awards are given to companies which demonstrate the best advancements in design and engineering.

For 2009, Fitbit was named an honoree and also named the best in the Health and Wellness category. This also means the Fitbit will be displayed at the 2009 Consumer Electronics Show, which is run by the CEA and is the world’s largest consumer electronics tradeshow.

Fitbit is public


So we were excited to finally be able to tell people what we were working on.

Check out our presentation at Techcrunch 50.

We were also named one of 5 runner ups for the winner of the conference.

We’ll be announcing Fitbit at Techcrunch 50

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We’ll be announcing Fitbit at Techcrunch 50 in San Francisco.  We look forward to telling you all about what we are working on Tuesday, September 09, 2008.

See you then!