So, I'm trying to figure out how to let merchants input wholesale prices and retail prices alongside eachother.

I had in mind just to have all input fields editable, and then mirror the users action (e.g., a user inputs a price without VAT, the corresponding input field WITH VAT would then be auto-filled) - can't make this work with the devs though, so trying another approach.

A problem I keep running into is the number of digits - being able to input an appealing price, might result in a price having 3 digits - to make net calculations correct.

I've been searching the internet for examples on someone who did this (Shopify, Faire, Amazon, etc), but have been struggling to find anything.

Input is very welcome, and references if you've seen someone else do this in a smart way. Thanks a bunch.

What I'm trying to do so far..

  • 4
    Your devs are not being honest with you - what you want should be easily achievable using any number of flavours of javascript. Secondly, I think you probably need legal/accounting advice about rounding numbers more than you need UX advice. If you have legal and accounting departments, go ask them how rounding works in this situation and then get your devs to apply those rules in the build. Commented Apr 14, 2023 at 8:13
  • Nice job asking a question with clear, visual examples of what you're explaining.
    – JohnGB
    Commented Apr 14, 2023 at 14:17
  • I'm not sure I understand this question correctly, but as far as I know this is really trivial and every eCommerce and accounting system has this feature. You can even do this with a spreadsheet, so I'm not sure I understand correctly, especially considering you say developers can't do this (and if that's what I think it's, it's the first thing you learn in a programming course)
    – Devin
    Commented Apr 14, 2023 at 16:01

3 Answers 3


Firstly, you need to be aware that although some countries (e.g. Denmark) have consistent 25% VAT rate, other countries (e.g. Germany) have multiple VAT rates depending on the product and service, so you can't simply select the country and know the VAT rate unless it's for a specific group of products that all have the same VAT rates applied.

It terms of how your pricing is entered, that should come down to how your customers want to enter the pricing. For some, the pricing will be based on costs plus markup, and they won't be bothered by how pretty the end price is, but others may find it important. Unless you know for sure how they want it done, you can't really say a given solution is better than another for your specific customers.

That said, if I were trying to make a generic solution for a range of customers and I wasn't sure which method they used, I would suggest exactly what you already have there, only if the option for "Entering prices incl. VAT" is disabled, I would also then show or enable a button to prettify the final prices. You'd need to work on what description would be clearest to your customers, but some possible names could be "Round VAT incl. prices", or "Prettify final prices". Essentially the button would open a small dialog that would let a customer choose the parameters for the prettifying. It could be just rounding to the nearest X cents, or some smart pricing system. That's a different UX challenge. However, what is important, is that it would change the price ex. VAT to have a final price incl. VAT be pretty.

It may also be a reasonable solution to have a "suggested ex. VAT price" column and customers can use as a guide, but there are few situations where I would think that would be a better solution.


If these price values are used for searching / filtering, then I would round the numbers in all cases. Yes, if converted, that would not be the same. But for humans it is much more convenient to work with "round" numbers than with randomly looking ones. In your example, I would round them as follows:

  • 20,39 - 24,90 --> 20 - 25
  • 20,58 - 24,90 --> 20 - 25

Also I would not provide any text explaining the rounding. Or if provide, then I would just put a small "?" icon (single icon for the whole screen/page, no reference numbers etc.) and nothing more. Because if the numbers are not self explainable, then something is wrong.

If you are unsure, how well will it be acceptable by the users, you can suggest 2 options: One as in your example and one as I suggested. Ideally, don't pick any of them as default, but use for 50% users the 1st approach as default and another as alternative, and for 50% users use the 2nd approach as default and the 1st as alternative. Then see what will be the preferences.


If we are talking about accounting each user MUST see correct arithmetic calculations which he could check with calculator.

To make this possible:

  • add VAT column
  • if user enters price excl. VAT, adjust price incl. VAT
  • if user enters price incl. VAT, adjust price excl. VAT

Above adjustments should be done to make verifiable calculations. So, if it's allowed to have 3 digits after decimal point it should be displayed. If no, some intelligence should be added to adjust both prices based on VAT value to avoid 3rd digit.

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