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# How to use formula fields in your tables
- URL: https://blog.jestor.com/how-to-use-formulas-in-your-tables/
- Published: 2026-09-16T18:50:07.000Z
- Updated: 2026-09-16T18:50:07.000Z
- Author: Bruno Bannach

**Formula fields in tables** calculate a value automatically from other fields on the same record, so the number is always current and nobody maintains it. In **Jestor**, you add a formula column, reference the fields you need and the result recalculates on its own.

## Why calculated columns beat manual ones

A number typed by a person is correct at the moment it is typed and drifts from then on. A number calculated from its inputs stays correct as long as the inputs do.

That difference matters most in financial data, where a stale figure leads to a payment that is wrong rather than just untidy.

Common calculations teams need:

- An overdue amount including interest
- The total of an order from its line items
- Days remaining until a due date
- Margin from price and cost
- A balance of contracted versus consumed

## What a formula can reference

| Source                     | Example                   | Result                        |
| -------------------------- | ------------------------- | ----------------------------- |
| A field on the same record | Amount                    | Base of the calculation       |
| Several fields combined    | Price and quantity        | Line total                    |
| A fixed multiplier         | Amount multiplied by 1.10 | Value plus ten percent        |
| A date field               | Due date against today    | Days remaining or overdue     |
| A connected record         | Data from a linked table  | Calculations across relations |

## Step by step to build one

1. **Add a column** and choose the formula field type.
2. **Name it clearly**, such as amount with late interest.
3. **Search for the field** you want to use as the base.
4. **Write the operation**, using the asterisk for multiplication and standard operators.
5. **Express percentages as multipliers**, so a ten percent increase becomes multiplication by 1.10.
6. **Check the result on real records** before relying on it.

## Why the field type of the inputs matters

A formula can only calculate on numeric data. If the amount was stored as text, the sum silently fails or returns something meaningless. That is the most common reason a formula does not work, and it is fixed by using the right field type from the start.

- **Calculated automatically:** the value updates with its inputs
- **No export needed:** the calculation lives with the data
- **Readable operators:** standard arithmetic, no scripting
- **Foundation for automations:** a calculated field can trigger a rule

## Frequently Asked Questions

### How do I add ten percent in a formula?

Multiply the base field by 1.10, which returns the original value plus ten percent. See [jestor.com](https://www.jestor.com/?ref=blog.jestor.com).

### Why does my formula not calculate?

Usually because the input is stored as text rather than as a number or currency field.

### Does the result update on its own?

Yes. The value recalculates whenever the fields it depends on change.

## Video Tutorial: Step by Step

With **Jestor**, you can automate workflows, connect teams, and build internal systems your way, all without code and powered by **AI**. Discover Jestor at [jestor.com](https://www.jestor.com/?ref=blog.jestor.com) and see how to take your company's operations to a new level of efficiency and control.