Estimating a duration in days from a number of months is essential in project management, finance (interest calculations, repayment deadlines) and everyday life. Precision depends on the definition of the month used.
How it works
Using the average month convention (30.44 days), simply multiply the number of months by 30.44. For a quick approximation in everyday life, use 30 days per month.
📐 Formula
Days = Months × 30.44 (precise)
Days ≈ Months × 30 (quick)
📊 Reference table
| Months | Days (×30.44) | Days (×30) |
|---|---|---|
| 1 | 30 | 30 |
| 2 | 61 | 60 |
| 3 | 91 | 90 |
| 6 | 183 | 180 |
| 9 | 274 | 270 |
| 12 | 365 | 360 |
| 18 | 548 | 540 |
| 24 | 730 | 720 |
💡 Practical examples
Example 1: 3 months
3 × 30.44 ≈ 91 days. Duration of a fiscal quarter or a probationary period.
Example 2: 6 months
6 × 30.44 ≈ 183 days. A semester, useful for construction projects or subscriptions.
Example 3: 18 months
18 × 30.44 ≈ 548 days. Duration of an average software development project or a training contract.