Introducing CalcStack - interactive calculators for your websites

I’m super-pleased to unveil the brand new CalcStack; a combination of much design, development, testing and refinement over the past several months, plus valuable collaboration with several prominent RapidWeaver users in this community.

What is CalcStack? A need frequently arises in modern websites and webapps to provide users with interactive calculators. Calculators are often needed for tasks like shipping estimators, product or service quantifiers, simple infographics, quote forms, savings and interest calculators, conversion calculators, educational purposes and various other tasks.

CalcStack lets you construct a variety of simple and more complex number calculators to go on your websites. You’ll find the intuitive user interface makes CalcStack both quick and easy to configure within Stacks 3. No code is required to accomplish the basics. Generated calculators are really fast, HTML5 valid, fully mobile-first responsive and styled attractively with Bootstrap to compliment the rest of your website. Compatibility is provided for all major themes.

Potentially CalcStack could save you a fortune in having calculators custom coded for your website. CalcStack brings the added time-saving flexibility of being able build and update your own calculators independently - at any time.

Lots of options exist for generated answers; including the ability to copy them to a clipboard, tweet them with a message or pass them onto another page or contact form. Additionally if you already use FormsPlus, you will find CalcStack integrates seamlessly with your existing forms!

A 20 minute video has been published here that demonstrates the basics of CalcStack and how to build some more complex implementations. The same RapidWeaver 7 project file used in the video is available here and you can find the rest of the documentation and a free demo version here on the product page for download.

If you have any questions about CalcStack or require support, please get in contact with me direct via email. The RW announcement forums are not always a good place to raise a support request. It is very noisy here and I get loads of notifications everyday; so sometimes I miss questions. I work on a zero inbox policy, so anything emailed to me is typically answered same-day. :slight_smile:


Hi Will CalcStack looks very promising, wonder if it’s similar to the Formula stack of 1LD?
Will have a look at the video later, yes indeed great if it’s integrate with the existing forms as FormPlus stack etc. Will be very useful… looking forwards to see all the possibilities of this stack.



I was highly anticipating this stack since its announcement as I know and have many use cases for this functionality – instant buy :wink:

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Now, that answers a need. The integration with FormsPlus is extremely useful.

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I’m extremely excited about this Stack. It’s been wonderful working with Will and getting it integrated with FormsPlus. Fantastic work Will!



Just watched the video Will and it looks excellent and offers lots of exciting possibilities. And thanks for taking the time to put that video together and explain it so well. Much appreciated.

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Hi Will I had just a more in depth look at your CalcStack… looks really great.

Wonder if it’s similar to the Formula stack of 1LD?
And if it would work/ integrate with the Foundry stacks? -would be great at a pricing page for quotations.
So how would this integrate with the FormPlus stack?


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Thank you all for the really positive feedback about the new CalcStack. I can’t believe how many copies have been sold when I logged in and checked the stats at the weekend - I nearly fell backwards off my chair!

A few feature requests were received by email, and I’m happy to report that every single one has been incorporated into the 1.1.0 free update going out tonight, together with a couple of other useful changes…

CalcStack 1.1.0

  • Warning messages are now clearly displayed in edit mode, if form inputs have no name attributes provided
  • Continued improvements and easier integration with FormsPlus
  • The range slider now supports negative numbers (e.g. -17) and decimalised steps (e.g. 0.25, 0.50)
  • You can now customise the width of the range legends (green value balloons) in the CalcStack style settings
  • Added the ability to have CalcStack ‘write’ calculated answers into other parts of the page, including blocks of text, link buttons and other input boxes. See the website for further setup details about this
  • Support for optional sound effects (like clicks), for when calculation inputs are changed by the end user - the sustainable transport infographic example on the website demonstrates this nicely
  • New advanced option to have number input boxes automatically focused (selected) on click, for better accessibility and less clicking
  • A couple of other minor changes to the underlying source code

I don’t normally post details of minor ‘point’ release updates on these forums, but thought I would on this occasion to demonstrate that this stack is actively being developed and is evolving all the time.


Great Support Will ! And very useful new features in this update…

A really must have stack for every RW user.


I’m so excited to check this out. Have not had time to work on my site lately, but I think this will be an amazing addition, as are all your stacks, @willwood.

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Yes indeed looking great as all work of Will. Support always a 10/10.


is there a way to prevent the input of negative numbers in a number box ?

I use the calcstack in a formsplus stack to let customers order products and negative input gives a wrong outcome.

Here’s a simple test I’ve done, the calculation is simple but what my test does demonstrate is that we can get multiple answers from one input and that answers can be shown in std text stacks (HeaderPro in this case).
I’m going to have fun with Calc :slight_smile:


Looking great Paul :+1:

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Instant Buy. Thank you very much!


Finally have some time to look at this stack. Just purchased and listening to your soothing voice on the video :slight_smile:thanks again, @willwood :slight_smile:


Me too, just purchased the CalcStack.
As Lisa says ‘Will Woodgate has some of the best Stacks and Support out there’, no doubt about it :+1:


I finally got around to use the CalcStack and it exceeded all my expectations :thumbsup:
Great job Will!


Thanks, that’s brilliant to hear! :+1:

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Yes, in fact, it’s a great stack :slight_smile: