A calculated field is a custom field type whose value Lineup works out automatically from other data, instead of someone typing it in. You define the rule once — for example, "if this person's email ends in @example.com, label them an Example employee" — and every record that has the field gets a value that stays current on its own. When the underlying data changes, the calculated field updates to match.

Why should I use them?

• To stop maintaining data by hand. No more re-tagging people or re-counting seats every time something changes.
• To make your data reportable. Turn scattered details (email domains, start dates, seat records) into a single clean value you can filter, group, and export on.
• To keep your people consistent. One rule applies to every record, so you don't get five different spellings of the same category.

Calculated fields are set up in the custom field builder, alongside your other custom fields. 

Some things to know before you start

A calculated field is a new custom field type. A calculated field belongs to either a Person or a Team. It appears on that record just like any other custom field.

They're read-only. Because the value comes from a formula, nobody can type over it - not on the record, not in an import. If a value looks wrong, the fix is in the formula or in the source data. 

What a calculated field can store. After you select your calculation type, you'll choose one of two output types:

You pick one calculation type per field. There are four, covered next. If you need to combine them — say, a percentage built from a count — you build one field for each step and point the second at the first. See Using other fields as inputs.

The Four Calculation Types

1. Mapping - "If the value is X, show Y"

A Mapping field looks at one other field and translates its value into an output. Think of it as a lookup table: you list the cases you care about, and optionally a fallback for everything else.

How to set it up:

1. Choose your Output. Choose between Text or a Defined list of values.  If Defined list of values is chosen, you can define those output values below. 
2. Set your Mapping Calculations. Chose from system or custom fields to be mapped to another value. 
3. Map your values. These are this, then statements. First determine equals, contains, starts with or ends with, then enter the original value, then determine the output value. Add additional conditions as necessary. 
4. Set an "Otherwise" output or leave it blank. If you leave it blank, records that don't match any condition simply have an empty field.

How a condition matches depends on the source field:

• If the source is a fixed list (a Dropdown, a Radio button group, State, Country, or another calculated field with a defined list of values), you pick one or more values from that list. The condition matches if the source equals any of them.
• If the source is free text (Short answer, Long answer, Email, Name, and so on), you pick a match operator

2. Duration - "How long since or until a date"

A Time span field measures the distance between a date field and today, and keeps that number current.

How to set it up:

1. Choose a date field. Any pre-created custom field that is a date field type, like birthday. 
2. Choose an direction. "Days since the date" for dates in the past or "Days until the date" for dates in the future.
3. Choose how to display it. Choose between whole days (e.g. 42 days), years / months / days (e.g. 1 year, 1 month, 12 days), or a decimal year format (e.g. 2.152 years) .

Example — "Days since joined"

Point the field at the person's start date, choose days since, and display it in years / months / days. Every record now shows current tenure without anyone touching it.

Good for: tenure, time since last certification, days until a term or membership ends, and any "how long has it been" reporting.

3.  Aggregate - "count or total across the seats on this record"

An Aggregate field summarizes the seats attached to a Person or a Team into a single number — how many there are, or a total, average, minimum, or maximum of one of their values. You can narrow which seats are counted with a filter.

How to set it up:

1. Choose an operation:
   • Count. How many seats there are. Count doesn't use a source field.
   • Sum, Average, Minimum, or Maximum. Pick a numeric field on the seat to work from.
2. Click "Filter which seats to include in calculation". Then select between "All of the conditions" if you want 'and' statement conditions. Select "Any of the conditions" if you want an 'or' statement condition. 
3. Build your conditions. Each condition tests one field on the seat: 

A count with no filter simply counts every seat on the record - for example, "total seats on this team."

Example — "Actual Number of Attendees (SME)"

On a Team, count the team's seats where:

• (Post-Event) ABCD Credits Earned is none of 0
• Any of —
• (Post-Event) EFGHI Credits Earned is none of 0

Using "Any of" means a seat is counted once if either credit field has been filled in, so nobody is double-counted when both are populated.

Good for: attendance counts, total credits or hours across a person's seats, roster sizes, and any "how many of these meet the bar" metric.

4. Arithmetic - "Calculate from other fields"

What it does. An Arithmetic field combines numbers from other fields, other calculated fields, and fixed values you type in, using add, subtract, multiply, and divide.

How to set it up: build the calculation from operands (a number field, another calculated field such as an aggregate, or a constant) joined by operators.

• Two things to know before you build one:
  There's no operator precedence. The calculation runs strictly left to right, so a + b × c is treated as (a + b) × c, not a + (b × c). Order your operands to get the grouping you want.
• Results are rounded to 4 decimal places, with trailing zeros trimmed — 84.00 displays as 84.

When the field comes out blank: if any input has no value, if the result is too large to store, or if you divide by a value that turns out to be zero, Lineup leaves the field empty rather than showing 0 or an error. Dividing by a constant 0 you typed in yourself is blocked when you save, since it could only ever produce a blank.

Worked example — "Actual vs Targeted % Attendees"

Actual Number of Attendees (the Roll-up field from the previous example) ÷ Target Minimum Number of Attendees (a number field) × 100

This gives the percentage of the attendance target that was actually met — and because the Roll-up updates as seats change, the percentage does too.

Good for: percentages, per-person averages, ratios, and any figure you'd otherwise work out in a spreadsheet after export.