AMB Robotics Calculator

After months of hard work, I’m proud to announce the release of the new online version of the AMB Robotics Calculator! You can find it now at

The site features nine calculators:

Mechanism Calculator

Find the properties of a mechanism given its gear ratio, or to find the proper gear ratio needed to give the mechanism certain properties

Gearbox Options Selector

Find sets of gears that produce the desired overall ratio, filtered by restrictions on gear sizes and spacing. Useful for designing gearboxes without guess-and-check or testing geometrical interferences.

Chain/Belt C-C Distance Calculator

Determine the proper center-to-center spacing between two sprockets or pulleys based on either the belt/chain length or an approximate center-to-center distance

Reduction Swap Selector

The robot is already manufactured and you find you need to change the reduction of a mechanism. This finds the options for reductions of a desired ratio while keeping the same center-to-center distance

Drivetrain Simulator

Find the proper gear ratio for your robot’s drivetrain based on the distance you want to travel as quickly as possible. Featuring “predictive stop” mode where the simulator attempts to stop at the target distance at zero speed.

Projectile Trajectory Calculator

Plan the trajectory of an object launched by a shooter based on the initial or target values. Includes a more accurate method for calculating the drag coefficient of a ball using empirical testing (in the docs).

Pneumatics System Simulator

Determine how many air tanks your robot needs based on the number and size of its cylinders and how often they fire

Beam Bending Calculator

Check the deflection or twist in an extrusion of uniform cross-section. Helpful for determining whether a profile or axle will be strong enough to carry the desired load

Lead Screw Calculator

Determine the properties of a lead screw based on its dimensions and materials, and convert between rotational and linear motion and force

All calculators feature custom URLs to save your calculations for future use and share with teammates. The majority of inputs are available in either imperial or metric units. All calculators are fully documented with derivations for most equations. All of the calculators should work on mobile as well, though I admit the formatting isn’t perfect.

Thanks to FUN for sponsoring the calculator website. For any questions, comments, or suggestions, feel free to reach out by PM or email. Happy robot building!


This looks awesome! Thanks for sharing, love that it’s a website and not another google sheet to keep track of. Something seems off on where the red line ends up in obstacle distance. Both Height and distance appear to be scaled by a factor of ~3.33.

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Of course when I try to add some basic input validation the morning of release it introduces bugs that I don’t catch. And you’re right about the obstacle problem, it accidentally got converted to meters when you input feet (factor of 3.28). Should be fixed now :slight_smile:


These are two of my favourite features. The docs for each of the calculators are incredibly thorough and well explained. Thanks for all the hard work that went into this incredible resource!


This is phenomenal!
Great job!


This looks so cool!! I’m definitely going to get distracted while playing around with it :joy:

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So this is like the jvn but like, new, updated for motors, and more features?

Yes in a sense. Much of what JVN’s sheet does is included.

I’ve had the AMB calculator as an Excel sheet since 2017 and updated it every year or two. It’s slowly grown over the years to include more and more useful calculations. But I’d say this is the biggest update yet, moving it to a website instead of Excel and adding a bunch of new features.


One of the “worst” parts about the AMB calc in the past has been trying to remember where I’d saved the most recent version :joy: (or find the latest thread here with the link). Absolutely love the updated feature set, and an easy to remember (with shareable links) website URL to boot!

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Thank you @AriMB for the continued hard work on this!


my only request.

When you copy and share the link. and all the team members are sharing links to designs.

I wish there was a field at the top that let me give it a name ( and that was also in the shared URL) so I can tell each mechanism ratio from the other mechanism ratios.

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Thanks for the suggestion. I added a custom title option for each calculator, right under the main heading.

The title is always the first query parameter after the web address so URLs are easily identifiable without opening them. The title is also copied into the tab title to make it easier to tell apart multiple tabs of the same calculator.

As a note, I’ve thought about what’s the best way to keep track of a bunch of calculator URLs for the robot that will get updated throughout the season. My suggestion for my team will be to open a google doc with a section for each subsystem. Any calculations will get their URL copied to that document (with a word or two description) so they can be referenced later. If changes are made the URL will get updated, but a record of the previous calculations is saved in the file history in case we need to revert something.


What happens if two folks use the same title? Say, if I use “winch test” will it override your winch test? Might need a unique identifier or something on the end of so.

That’s not a problem. The title isn’t saved anywhere other than as a URL query parameter, same as all the other inputs you change in the calculator. It pulls double duty in that way: showing the title as a URL parameter makes it identifiable without opening the page, and when the page is opened the title is read in like any other option. As long as you don’t confuse yourself, you could make every calculator with the same (or no) custom title.

this is great thank you!

so our team is talking about this. ATM it looks like we will be using linktabs in onshape and appending a version to the name to keep track, and to keep a history of the mechanism with its calculator.

there was talk of doing some sort of Featurescript that could generate the AMB URL from the selected gearbox. But that would be a way future thing.


Interesting idea, I hadn’t thought about using Link Tabs. Playing around with it quickly, it doesn’t seem like the embedded tab holds onto whatever URL you originally give it instead of allowing the URL query parameters to be changed. That seriously messes with the link sharing/saving. So when you close the document and reopen it, or try to open the link in a regular tab, it just sends you to a blank calculator (which kind of defeats the purpose). However, pasting a URL in with query parameters does seem to work. So I guess you could work in the calculator in a normal tab and then copy into Link Tabs to save your work.

I don’t have a ton of experience with Link Tabs though, so maybe you can get it to work correctly. And if anyone has more information on how Link Tabs works in the background, I can try to see if I can figure out a way to change the site to make it work natively (but I wouldn’t rely on that at this point).

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The biggest downside of moving from Excel to a website is the reliance on an internet connection. This isn’t a dependency I take lightly, as not everyone has access to stable internet connection at home or in their team spaces.

To remedy this, I have been working for the past few days to package the website as an installable application that doesn’t rely on the internet. You can download the installer by going to the normal website and clicking the “Offline Installer” button in the top right corner.

After running the installer you should see AMB Robotics Calculator as a new program in the start menu. With this program, you can both create links to share with online users and open other users’ saved links all without an internet connection. The program is only available for Windows at the moment, but if there is a strong enough demand I can look into packaging for Mac and Linux.

For users with an internet connection, I still recommend using the online site over the downloadable option to make sure you get any updates or bugfixes automatically. I will do my best to rebuild the application whenever updates are made and post here to let users know to download the new version, but I can’t guarantee that it will happen immediately. I bug tested the program myself and it seems to work properly, but if anyone finds something that I missed please let me know so I can fix it.


With the new season and lots of new robots to be designed, I’m bumping this thread for people who didn’t see the release over the summer


Over the past few weeks I’ve had a chance to add two new calculators to the site. The updated site is still in the same place, Previous calculators haven’t been changed. The new calculators haven’t been thoroughly beta tested, I’m hoping releasing the update early will allow for the community to find any problems before the season.

Motor Curve Generator

Compare motor curves between different motors, with varying voltages, current limits, and gear reductions. At this point the motor data is collected from each manufacturer, not tested on a common dynamometer and therefore technically not directly comparable. Hopefully soon we will get a single source of data for all of the motors, ideally an independent source.

Planetary Gearbox Calculator

Find the combination of planetary stages to get as close as possible to the desired ratio. It currently does not check whether the combinations given are within the load ratings, as there are a lot of missing values with the new motors and the MAXPlanetary table is all green up to three stages. If this is a highly requested feature, I’ll think about adding it.


I noticed that there is a difference between AMB and Recal/WCP calculators for CC on this belt ratio with HTD Belts. It is fine with normal more common pulleys like 24-24 but this one is odd.
Something completely random but very odd.

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