Everyday annuity problems come down to one relationship between 8 figures. This calculator takes final balance, initial deposit, annuity amount, annual growth rate, periodic growth rate, rate of return, length of annuity, return status and turns them into annuity frequency, with the working shown so you can check the result rather than simply trust it.
What Is the Annuity Calculator?
It is built around annuity frequency, and it works the same way whether you are checking a homework answer, confirming a colleague's figure, or working something out for yourself. Everything runs in your browser, so nothing you enter is uploaded anywhere.
How the Annuity Calculation Works
The steps are applied in order, so an output that depends on another output updates as soon as the underlying figures change.
The relationship between final balance, initial deposit, annuity amount, annual growth rate, periodic growth rate, rate of return, length of annuity, return status and annuity frequency is fixed, so the same figures always give the same answer. That makes it a good cross-check: run the numbers a second way and see whether the result agrees.
Getting a Result You Can Trust
For anything that matters, write the inputs down next to the result. A calculation you can reproduce is worth far more than a number you cannot explain, and it takes a moment to record final balance and initial deposit and annuity amount and annual growth rate and periodic growth rate and rate of return and length of annuity and return status alongside annuity frequency.
Frequently Asked Questions
What do I need to work out annuity frequency?
Enter final balance, initial deposit, annuity amount, annual growth rate, periodic growth rate, rate of return, length of annuity, return status. The calculator then works through the relationship and reports annuity frequency.
What does the annuity actually calculate?
It takes final balance and initial deposit and annuity amount and annual growth rate and periodic growth rate and rate of return and length of annuity and return status and converts them into annuity frequency using the standard relationship for this problem. Each step is applied in turn, so every output is traceable back to the numbers you typed in.
How should I enter final balance?
Use the value you actually have, in the unit shown next to the field. Enter every value in the same unit system. The calculator assumes the figures you supply are consistent, so it cannot correct a mistake that happens before the calculation starts.
Why does a small change in one value move the answer so much?
That happens when an output depends on a ratio, because dividing by a small number magnifies any change in it. Check the units first, then check whether the value you entered is in the range the relationship was designed for.
Can I use this for a quick estimate as well as a precise answer?
Yes. The calculator is built for quick checks, so round your inputs to a sensible number of significant figures and the result will be just as useful. If you need more precision, keep the same method and add digits to the inputs rather than adjusting the method itself.