The formula
Monthly saving neededExcelGoogle Sheets
=PMT(B2/12,B3*12,B4,-B1)In D1 → $460.44
With 0% returnExcelGoogle Sheets
=(B1-B4)/(B3*12)In D2 → $500.00
✓ Tested. All 2 Excel results in this example were recalculated in LibreOffice Calc 25.2 and matched the values shown.
Worked example
Paste the data below into a blank sheet starting at cell A1 (or download the cheat sheet, where every example is set up). Highlighted cells hold the formulas and show the expected results.
| A | B | C | D | |
|---|---|---|---|---|
| 1 | Goal | 20,000 | $460.44 | |
| 2 | Annual return | 4.5% | $500.00 | |
| 3 | Years | 3 | ||
| 4 | Saved already | 2000 |
How it works
- B2/12
- Monthly return.
- B3*12
- Months until the goal.
- B4
- What you have now (positive here).
- -B1
- The goal as a negative future value, so the result is a positive deposit.
Common errors and fixes
Negative result?
Swap the signs: current savings positive, goal negative (or vice versa and add a minus).
Why does the formula return #NUM!?
Months is zero.
Does this work in Google Sheets?
Yes. The formulas on this page work the same way in Google Sheets.