Monthly savings with returns
v1aportetasamesesahorro_finalHow it is worked out
See what your monthly saving grows to once it also earns a return.
Each contribution arrives at a different moment, so each one earns for a different length of time: the first works for all sixty months and the last for none. Three hundred thousand a month for five years at 9 % a year grows to 22,627,241.
The expression that runs
aporte * ((1 + tasa / 100 / 12) ^ meses - 1) / (tasa / 100 / 12)The fields arrive with an example filled in: put your own numbers in and run it again. You can also edit the formula to fit your case.
What if the formula were yours?
This calculator is not hand-written: it is an Axioma formula. Open it in the editor to see how it is built, adapt it to your case and create the ones you need.
Where the difference comes from
Put aside with no return, sixty contributions of 300,000 would be eighteen million. The result is 22,627,241, so the return added 4,627,241 without you having to contribute anything more.
The formula is the future value of a series of payments: it adds up every contribution, each multiplied by how much it grew since it arrived. Doing it month by month would give the same figure with sixty multiplications instead of one.
Time does more than the amount
Doubling the contribution to 600,000 doubles the result, but doubling the term to a hundred and twenty months takes it far beyond double, because the earliest contributions have twice as long to grow.
That is why starting early with little usually beats starting later with more, and why skipping the contributions at the beginning costs more than skipping the ones at the end.
What the number leaves out
The result is nominal and gross: it takes off no inflation, no management fees and no tax on the return. With inflation at 5 % a year, a nominal 9 % is roughly a real 4 %.
Nor does it assume the rate will hold for five straight years. It is there to size a goal, not to promise an exact figure.
Frequently asked questions
- Are the contributions at the start or the end of the month?
- This formula counts them at the end of each month, which is the usual convention. If you contribute at the start, the real result is slightly higher because every contribution earns for one more month.
- How much would I have to save to reach a target?
- It is the same calculation the other way round: solve for the contribution from the amount you want. That is a formula you can write in the editor starting from this one.
- Can I set the return to zero?
- Not in this formula, since it would divide by zero. With no return the calculation is simpler: contribution times number of months.