What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No signup required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.


JotForm Support
You cannot use the specific cell in the matrix field in the "IF" statement of the conditions. What you can do is pass the total calculated value in a separate text box or form calculation widget and use that in your conditions as the validation.
1. Below are guides to help you get started on doing calculations in your matrix field:
https://www.jotform.com/help/343HowtoPerformFormCalculationintheMatrixField
https://www.jotform.com/help/414HowtoPerformCalculationintheMatrixFieldThroughCondition
2. Now to do that validation, here I setup a "Text" field as the warning message:
3. I then setup a conditional logic wherein I will hide the submit button and show the "Text" field if the total value is less than 100.
4. Here's a sample form that I made to see how it work.
https://form.jotform.com/70371139777968
I hope that helps. If I misunderstood your concern, please do provide us more details.

Thanks for the reply. Yes, you understood my doubt correctly.
But the issue is that we have 3 columns which need validation. If we use 3 form calculation widgets with 3 different messages, it will confuse our customer.
In order to make it easy, we can make a cell in the matrix which shows the total and have a validation error by changing the color of 'total cell' to red (rather than a message), it will not confuse the customer.
I know how to do the total in a matrix, but I don't know how to do validation in the cell of the matrix.
Please guide. Thanks

JotForm Support
Hello drishtee_,
Can you please explain the validation condition on how you want to calculate the value of all the three columns of matrix field? Please explain your requirement a bit more in detail and we will try to help you if it is possible to achieve your requirement with one single calculation widget.
We will wait for your response.
Thank you!

Vegetable basket subscription model
a. customer is asked to enter number of family members (basket is designed on the basis of number of family members  500 gm per family member per day)
b. the basket is delivered every monwedfri
c. the customer has to plan for the entire week in advance
d. Row  name of vegetable, Column  MonWedFri
e. customer can choose any vegetable in any quantity and plan the basket, but the total quantity shouldn't exceed 500 gm per family member per day
Link  https://form.jotform.me/63612568159463

JotForm Support
Hi,
I'm currently checking your requirement. Please allow me some time to further investigate. I'll get back once I've found results.
Regards

JotForm Support
As per further checking, I think the requirement would best achieve by creating 3 Form Calculation Widgets as it should evaluate that the family shouldn't exceed 500 gm per day.
For example, If every column has a total greater than 500 then set the condition to hide the Submit button.
Please let us know if you need further assistance.
Regards 
The value is not fixed. It is dependent upon the input by the customer. If customer enters 1, the value is 500, if customer enters 2, value should be 1000, if customer enters 3, value should be 3000. Can't this be in cell matrix itself.

JotForm Support
I'm sorry, I'm quite confused with your calculation. What is entered on the matrix field? Is it quantity of items OR grams? If you could give us a complete example with calculation then that would help us.
Note that you cannot assign direct value on your matrix field, you also cannot make a validation on a specific cell on your matrix field.
The only way I see this is possible is by recreating the matrix field into separate text boxes, radio buttons, check boxes, drop down and other default form fields that can be use in the conditional logic.
I suggest checking the following links that would help you make further calculation and advance setup:
Conditional Logic: https://www.jotform.com/help/57SmartFormsUsingConditionalLogic
Conditional logic to perform calculation: https://www.jotform.com/help/268ConditionalLogicInsertsTextCalculationIntoAField
Calculation using widget: https://www.jotform.com/help/259HowtoPerformFormCalculationUsingaWidget
Assigning calculation value on fields: https://www.jotform.com/help/301HowtoAssignCalculationValue
I hope that helps.

Please refer the link  https://form.jotform.me/63612568159463
In the link,
a. first, a customer enters the 'no. of family members'
b. on the second page, a matrix appears, which has the quantity of potato & tomato calculated on the basis of a formula assigned to the same cell. The customer can also change the potato or tomato quantity as desired
c. In the last cell, the total of the potato quantity and tomato quantity is calculated.
d. We want that total to be ('no. of family members' x 500). If that's not the case, the form shouldn't submit.

JotForm Support
Hello,
I've tested your form and cloned it on my side in order to test it. Firstly, be aware of that you have too many missing conditions and you have added an autoresponder email but you do not request any email from your users. So, your autoresponder email has wrong settings.
Related to your questions:
a. first, a customer enters the 'no. of family members'
As I have seen you have already set this calculation correctly with conditions.
Also, you can use a dropdown list instead of a textbox for "no. of family members" field. So that, you can set calculation values easily as you can see the screenshot below:
b. On the second page, a matrix appears, which has the quantity of potato & tomato calculated on the basis of a formula assigned to the same cell. The customer can also change the potato or tomato quantity as desired.
As I've seen you've already done this with conditions. If you have any problem, for detailed information, please check the following guide: https://www.jotform.com/help/343HowtoPerformFormCalculationintheMatrixField
c. In the last cell, the total of the potato quantity and tomato quantity is calculated.
As I have seen you've already done this by adding a Form Calculation widget. It adds tomato and potatoes.
d. We want that total to be ('no. of family members' x 500). If that's not the case, the form shouldn't submit.
You can do this adding another calculation widget in order to calculate (no. of family members* 500). As you have already set the no. of family members required, the form will not be submitted if the user does not enter any value in that field.
As I have seen your form and calculations seem to work.
All in all, If you see any logical issue belongs to conditions, please check the documents that my colleague Charlie has already forwarded to you in the previous threads.
I hope this helps.
Thanks.