Scale Magazine Comparison Series                       
"FX-100 vs. 120-Z Comparison Test"

The most popular pages of this magazine are the comparisons between like-models of various scale companies.  We feel that it's important to compare and contrast like models in order to understand the differences between them.  After all - scales that look similar are often completely different.  This leads us to this week's comparison between the Gram Precision / Vector FX-100 and the My Weigh 120-Z.   These are both important scale models as they represent the lowest priced market entries by both companies.   It's not uncommon to find these scales selling for around $22 on the net.

Both the 120-Z and FX-100 share a similar design.   We feel that these two scales mark the best overall design of any value-priced pocket scale.  They are both small in size, but their expansion trays (cover upside down) expand the weighing surface. Their expanded weighing tray is larger than many other pocket scales (including scales that are much larger in overall size).   This is an important new design trend where form follows function - yet these scales are truly beautiful designs.    To compare the designs of the FX-100 & 120-Z against older pocket scales is sort of like comparing an Acura NSX to a Ford Pinto.   Make no mistake, the FX-100 and 120-Z are high performance mini pocket scales.

Gram Precision FX-100
My Weigh 120-Z
Accuracy  (as tested) +/- 0.3 grams* +/- 0.1 gram
Maximum Capacity
100 Grams
120 Grams
4 HBM Sensors
4 HBM Sensors
Weighing System
1.5" Aluminum Load Cell
1.5" Aluminum Load Cell
Stabilization Time
~1 Second
~1 Second
2 modes:Grams, Ounces
4 modes: Grams, Ounces, Pennyweight, Troy Ounces
Tare Max
100 Grams
120 Grams
No,  not calibratable by user
Yes, with 100g weight
5 Years with no fee
Lifetime / 30 years with no fee
Integrated Cover / Expansion tray
Integrated Cover / Expansion tray
Power 2 AAA Batteries - Not Included 3 Lithium Button Batteries - Included
Shenzhen China
Fuzhou China
Suggested Retail
Testing Results:

We tested 5 FX-100's and. 5 120-Z's.  All scales were put in a 70f room and allowed to sit for 24 hours before tested.   Our test facility is a controlled environment that allows us to fully evaluate scales.  First (if possible) we calibrate the scales using a 100gram F1 weight.  We use F1 test weights for all of our tests and record the results on a spreadsheet to fully compare the products.   Each scale is tested by placing a 0.5, 1, 2, 5, 10, 20, 50, and 100 gram weight on the tray 10 times.   The results are then compared for an overall accuracy number, skew (reproducibility) and stability.  Then we put the scales into a 45f refrigerator for 30 minutes,  removed them and then ran the tests again in order to test for temperature compensation.

There was a big difference in the accuracy of these two models. This is because the FX-100 is not recalibratable. This meant that at 100 grams the FX-100 always showed 100.3g on the display.  There is no way to adjust or calibrate the FX-100.  So, the FX-100 was always inaccurate by between 0.1g and 0.3g.   The 120-Z is recalibatable and thus it was able to show consistent results accurate within 0.1g.  The picture below shows our frustrating results.  

*We don't know why Gram Precision (Bonso) decided not to make the FX-100 recalibratable.  This led to a very frustrating lopsided test where the 120-Z was significantly more accurate than the FX-100.  Both the FX-100 and 120-Z use an FSCII Internal processor and 1.5" aluminum load cell with high quality HBM or equivalent sensors.  Both scales would have likely shown the exact same accuracy if the FX-100 had been able to be recalibrated.
The reason why this is particularly frustrating for us is that Bonso (the owner of Gram Precision / Vector) is a high quality scale manufacturer.  If a consumer purchases an FX-100,  takes it home and finds it to be inaccurate,  there is nothing they can do to fix the problem.  This could have been easily resolved by adding one more button to the front of the scale (like the 120-Z) to allow for user calibration.  We think perhaps Bonso is trying to keep the FX-100 as a low end model and thus reserved user-calibration for their higher end scales.
Mode FX-100 120-Z
Grams 100g x 0.1g 120g x 0.1g
Ounces 4.00oz x 0.01oz 4.25oz x 0.005oz
Troy Ounce  (no function) 3.860ozt x 0.005ozt
Pennyweight  (no function) 77.2dwt x 0.1dwt


Cosmetically the finish of both scales was quite perfect.  They both come in modern color-boxes with multi-lingual manuals included.  Both scales have their own design patents.

Both Scales have an integrated expansion tray

The 120-Z is operated by two large rubber buttons, one on either side of the LCD.  On button acts as On, Off and Tare and the other button changes modes.  The 120-Z reads in four standard modes: Grams, Ounces, Troy Ounces and Pennyweight. 

The FX-100 is operated by one small rubber button at the front of the scale below the LCD and one recessed button oddly placed on the bottom of the scale that you must press with your fingernail.   The button on the front of the scale acts as On, Off and Tare and the fingernail button on the bottom of the scale changes modes.  The FX-100 reads in two standard modes: Grams and Ounces.


Both Scales are Great Values.   The 120-Z has a higher capacity, reads in more modes, has the ability to be recalibrated and thus is more accurate.

Learn More about these Scale Brands:


We encourage you to provide feedback on this article and/or tell us your personal experience with a scale.

Important Disclaimer:   Scales are sometimes difficult to compare.  Our results are just a sample of tests done at random conditions.  The actual operating conditions of your scale may vary from our test conditions and your results may differ from our results.   We did our best to test the scales in a blind and unbiased manner.  We receive advertising and other consideration from companies  that support this site.  We do our best to not allow this to affect the results of our tests and evaluations.  However, we strongly recommend that you do your own comparison tests in your actual operating environment to determine which scale is best for your needs.    The terms My Weigh, Bonso, Gram Precision, Vector, 120-Z, FX-100, Pocket Tech, and all are trademarks or trade names of their respective parties.  Names are used for comparison purposes only and for the purposes of this article.  No other rights are expressed or implied.  This article and all images therein are copyright 


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