Why Do Some Excel Formulas Start With a “+”?

If you've encountered formulas in Excel that begin with a "+" symbol, you may wonder why it's used instead of the more familiar "=" sign.

Contents:

1. Quick Answer

2. Historical Context - Legacy from Lotus 1-2-3

3. Similarities and Differences

3.1. Percentage Formatting

3.2. Value vs. Formula Memory

3.3. Physical Key Location

Quick Answer

From a calculation standpoint, formulas that begin with + work identically to those that begin with = in most cases. For example:

=A1+B1  

+A1+B1 

Both will return the same result.

However, the equivalence is not absolute. There are subtle differences in behavior that can cause unexpected results, particularly when working with formatting or static values.

Historical Context

Legacy from Lotus 1-2-3

The use of + as the starting character for formulas originates from Lotus 1-2-3, a dominant spreadsheet application in the 1980s. In Lotus 1-2-3, all formulas were required to start with +.

When Microsoft Excel was introduced, it adopted the more intuitive = to start formulas. However, to support users transitioning from Lotus, Excel also allowed formulas to begin with +. This compatibility feature remains supported to this day, even though Lotus 1-2-3 has long since fallen out of common use.

Similarities and Differences

There are some subtle differences in behavior that can cause some unexpected results, particularly when working with specific formatting or static values.

1. Issue Percentage Formatting

When using numeric constants with a leading +, Excel may interpret the input differently than expected under certain formatting conditions.

For example:

Typing =50/100 into a cell formatted as a percentage, returns 50%. However when you type +50/100, the formula returns 0.5%, which isn't correct.

This behavior can lead to misinterpretation, especially when importing data or applying bulk formatting.

2. Value vs Formula Memory

Excel distinguishes between static values and formulas:

• Typing =100 explicitly defines the cell as a formula returning 100.

• Typing 100 enters a constant 100.

• Typing +100 will convert the cell from a formula into a constant value.

Unintended use of + may introduce errors or inconsistencies. So if you're looking to keep your values as a formula, you may want to explicitly use a =.

3. Physical Key Location

Another practical reason some users prefer starting formulas with a + is that it’s physically easier to type, especially on a standard keyboard layout.

For users working with a 10-key numeric keypad, common in accounting and finance, the + is positioned conveniently and aligns naturally with number entry.

This makes it quicker to begin simple calculations without breaking hand position, particularly when entering long sequences of numeric operations. While small, this ergonomic advantage can be noticeable for users entering large volumes of data or doing rapid tabular math.