# Easy Excel Formula to Allocate an Amount into Monthly Columns

Are you looking for an **Excel formula to allocate an amount into monthly columns** automatically? Spreadsheets like Microsoft Excel are powerful tools for managing and analyzing financial data. A common task is taking a total annual amount, such as a budget or revenue forecast, and spreading it evenly across 12 months.

In this article, we’ll show you a simple formula to do just that, as well as some more advanced techniques for allocating amounts based on custom monthly weightings, seasonality factors, and trend growth rates. Whether you’re managing a budget, forecasting revenue, or spreading out costs, these Excel formulas will save you time and help you work more efficiently.

## Simple Formula to Allocate Amount Evenly Across 12 Months

The easiest way to **allocate an annual amount into monthly columns** is to divide the total by 12. Here’s the formula:

=ANNUAL_AMOUNT/12

Where ANNUAL_AMOUNT is the cell reference containing your total amount for the year.

For example, let’s say your total annual budget is $120,000. Enter this amount in cell A2. Then, in cell B2, enter the formula:

=A2/12

This will allocate $10,000 to January. Copy this formula across the row to populate the amounts for the remaining months.

Annual Amount | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
---|---|---|---|---|---|---|---|---|---|---|---|---|

$120,000 | $10,000 | $10,000 | $10,000 | $10,000 | $10,000 | $10,000 | $10,000 | $10,000 | $10,000 | $10,000 | $10,000 | $10,000 |

### Accounting for Rounding Errors

One problem with simply dividing the annual amount by 12 is that it can sometimes lead to **rounding errors**. In the example above, $120,000 / 12 = $10,000 exactly. But what if your annual amount was $120,001?

$120,001 / 12 = $10,000.0833333…

Excel will display $10,000.08 in each month, which adds up to only $120,000.96 for the year. There’s a small $0.04 discrepancy due to rounding.

To fix this, use the ROUND function:

=ROUND(ANNUAL_AMOUNT/12, 2)

This rounds the result to 2 decimal places. You’ll get $10,000.08 in each month except December, which will get $10,000.09 to make up for the rounding error and ensure the monthly amounts add up to the annual total.

### Handling Leap Years

What if you’re allocating daily amounts and need to account for **leap years**? No problem – just use the DAYS360 function instead of dividing by 12:

=ROUND(ANNUAL_AMOUNT/DAYS360(DATE(YEAR,1,1), DATE(YEAR,12,31)), 2)

Where YEAR is the 4-digit year you want to allocate amounts for. This formula calculates the number of days in the year, accounting for leap years with 366 days, and divides the annual amount by total days instead of assuming 12 equal months.

## Allocating Based on Custom Monthly Weights

Sometimes you may want to allocate an annual amount into months based on **custom weightings** instead of spreading it evenly. For example, let’s say you run an ice cream shop and your monthly revenue allocation looks like this:

Month | Weighting |
---|---|

Jan | 2% |

Feb | 3% |

Mar | 5% |

Apr | 7% |

May | 10% |

Jun | 12% |

Jul | 15% |

Aug | 15% |

Sep | 10% |

Oct | 8% |

Nov | 6% |

Dec | 7% |

To allocate your annual revenue forecast of $500,000 based on these monthly weights, use the SUMPRODUCT function:

=SUMPRODUCT(ANNUAL_FORECAST, WEIGHTING_TABLE)

Where ANNUAL_FORECAST is the cell reference for your $500,000 forecast amount, and WEIGHTING_TABLE is the range containing your 2-15% monthly weighting percentages.

This formula multiplies each monthly weighting by the annual forecast amount, and sums up the resulting weighted allocation amounts, like this:

Month | Weighting | Allocation |
---|---|---|

Jan | 2% | $10,000 |

Feb | 3% | $15,000 |

Mar | 5% | $25,000 |

Apr | 7% | $35,000 |

May | 10% | $50,000 |

Jun | 12% | $60,000 |

Jul | 15% | $75,000 |

Aug | 15% | $75,000 |

Sep | 10% | $50,000 |

Oct | 8% | $40,000 |

Nov | 6% | $30,000 |

Dec | 7% | $35,000 |

Total | 100% | $500,000 |

Using this weighted allocation method, the months with the highest percentages (July and August at 15% each) get allocated the largest share of the total annual amount, while the slower months like January and February receive smaller portions based on their lower weights.

## Allocating Based on Number of Days in Month

Another common way to allocate amounts into monthly columns is by the **actual number of days in each month**. This is often used for fixed monthly expenses that get charged per day, like rent, utilities, or insurance premiums. Here’s the formula:

=ANNUAL_AMOUNT * DAYS_IN_MONTH / DAYS360(DATE(YEAR,1,1), DATE(YEAR,12,31))

Where:

- ANNUAL_AMOUNT is the cell reference for your total annual expense amount
- DAYS_IN_MONTH is the number of days in the specific month you’re allocating to
- YEAR is the 4-digit year you’re allocating for

This formula multiplies the annual amount by the ratio of days in the month to total days in the year.

For example, let’s say you have an annual insurance expense of $12,000. To calculate the allocated amount for January 2023, use:

=12000 * 31 / DAYS360(DATE(2023,1,1), DATE(2023,12,31))

Which equals $1,033.33, since January has 31 days out of the 360 day year in 2023.

You could automate this further by using the DAY and EOMONTH functions to dynamically calculate the number of days in each month:

=ANNUAL_AMOUNT * DAY(EOMONTH(DATE(YEAR, MONTH, 1), 0)) / DAYS360(DATE(YEAR,1,1), DATE(YEAR,12,31))

Where:

- MONTH is the number representing the month to allocate to (1 for January, 2 for February, etc)

## Allocating with Seasonality or Trend Factors

Finally, you can make your monthly allocation formulas even more sophisticated by incorporating **seasonality adjustments** or **trend growth factors**.

For example, let’s say your business experiences the following seasonal fluctuations in demand, represented as monthly adjustment factors (where 1.0 equals average demand, <1.0 is below average, and >1.0 is above average):

Month | Seasonality Factor |
---|---|

Jan | 0.8 |

Feb | 0.9 |

Mar | 1.1 |

Apr | 1.0 |

May | 1.2 |

Jun | 1.3 |

Jul | 1.5 |

Aug | 1.3 |

Sep | 1.1 |

Oct | 0.9 |

Nov | 0.8 |

Dec | 1.1 |

To apply these seasonality factors to a monthly revenue allocation, multiply the SUMPRODUCT result by the seasonality factor:

=SUMPRODUCT(ANNUAL_FORECAST, WEIGHTING_TABLE) * SEASONALITY_FACTOR

For example, the formula for January would be:

=SUMPRODUCT(500000, B2:B13) * 0.8

Which equals $8,000, reflecting that January revenues are typically 20% below average.

To further extend this to account for an expected revenue growth trend, use:

=(SUMPRODUCT(ANNUAL_FORECAST, WEIGHTING_TABLE) * SEASONALITY_FACTOR) * (1 + MONTHLY_GROWTH_RATE)^(MONTH_NUM-1)

Where:

- MONTHLY_GROWTH_RATE is your expected growth rate per month, expressed as a decimal (e.g. 2% growth would be 0.02)
- MONTH_NUM is the number of the month (1 for January, 2 for February, etc)

The ^(MONTH_NUM-1) part of the formula compounds the growth rate based on the month number, relative to the first month. So month 2 has growth of (1 + 0.02)^1, or 2% higher than January, while month 12 has (1 + 0.02)^11, which equals growth of 24.3% compared to January.

Combining these seasonality and trend formulas allows you to create detailed, customized monthly allocation models based on your business’ unique attributes and growth expectations.

## Summary

In conclusion, there are several useful **Excel formulas for allocating an annual amount into monthly columns**:

- Equal allocation across 12 months: =ROUND(ANNUAL_AMOUNT/12, 2)
- Daily allocation based on days in the year: =ROUND(ANNUAL_AMOUNT/DAYS360(DATE(YEAR,1,1), DATE(YEAR,12,31)), 2)
- Weighted allocation based on custom monthly percentages: =SUMPRODUCT(ANNUAL_FORECAST, WEIGHTING_TABLE)
- Allocation by actual days in each month: =ANNUAL_AMOUNT * DAY(EOMONTH(DATE(YEAR, MONTH, 1), 0)) / DAYS360(DATE(YEAR,1,1), DATE(YEAR,12,31))
- Allocation with seasonality adjustment factors: =SUMPRODUCT(ANNUAL_FORECAST, WEIGHTING_TABLE) * SEASONALITY_FACTOR
- Allocation with both seasonality and trend growth factors: =(SUMPRODUCT(ANNUAL_FORECAST, WEIGHTING_TABLE) * SEASONALITY_FACTOR) * (1 + MONTHLY_GROWTH_RATE)^(MONTH_NUM-1)

By using these formulas and techniques, you can quickly and accurately spread annual amounts across monthly columns based on your specific business needs and assumptions. This will help you save time, reduce errors, and create more robust financial models and plans. I hope you found this guide helpful – feel free to reach out if you have any other questions!

## People Also Ask

### What is the simplest formula to allocate an annual amount evenly across 12 months in Excel?

**=ANNUAL_AMOUNT/12**, where ANNUAL_AMOUNT is the cell reference containing your total amount for the year. For example, if your annual amount is in cell A2, you would enter

**=A2/12**in the first month’s cell and then copy the formula across the remaining months.

### How can I allocate an amount into months based on custom weightings in Excel?

**=SUMPRODUCT(ANNUAL_AMOUNT, WEIGHTING_TABLE)**, where ANNUAL_AMOUNT is the cell reference for your total amount, and WEIGHTING_TABLE is the range containing your custom monthly weighting percentages. This formula multiplies each monthly weighting by the annual amount and sums up the resulting allocation amounts.

### What formula should I use to allocate an amount into months based on the number of days in each month?

**=ANNUAL_AMOUNT * DAYS_IN_MONTH / DAYS360(DATE(YEAR,1,1), DATE(YEAR,12,31))**, where ANNUAL_AMOUNT is the cell reference for your total amount, DAYS_IN_MONTH is the number of days in the specific month, and YEAR is the 4-digit year. This formula calculates the allocation by multiplying the annual amount by the ratio of days in the month to total days in the year.

### How can I incorporate seasonality factors into my monthly allocation formula in Excel?

**=SUMPRODUCT(ANNUAL_AMOUNT, WEIGHTING_TABLE) * SEASONALITY_FACTOR**, where ANNUAL_AMOUNT is the cell reference for your total amount, WEIGHTING_TABLE is the range containing your custom monthly weightings, and SEASONALITY_FACTOR is the cell reference for the specific month’s seasonality factor.

### What is the formula to allocate an amount into months with both seasonality and trend growth factors in Excel?

**=(SUMPRODUCT(ANNUAL_AMOUNT, WEIGHTING_TABLE) * SEASONALITY_FACTOR) * (1 + MONTHLY_GROWTH_RATE)^(MONTH_NUM-1)**, where ANNUAL_AMOUNT is the cell reference for your total amount, WEIGHTING_TABLE is the range containing your custom monthly weightings, SEASONALITY_FACTOR is the cell reference for the specific month’s seasonality factor, MONTHLY_GROWTH_RATE is your expected growth rate per month (e.g., 0.02 for 2% growth), and MONTH_NUM is the number of the month (1 for January, 2 for February, etc.). This formula applies the seasonality factor and compounds the growth rate based on the month number.

Vaishvi Desai is the founder of Excelsamurai and a passionate Excel enthusiast with years of experience in data analysis and spreadsheet management. With a mission to help others harness the power of Excel, Vaishvi shares her expertise through concise, easy-to-follow tutorials on shortcuts, formulas, Pivot Tables, and VBA.