Future value calculator
1,000 invested at 5% per period for 10 periods grows to 1,628.89462678, of which 628.89462678 is interest. Enter one lump sum, the rate for each period and how many periods it compounds, with no deposits along the way. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Present value
- 1,000
- Interest rate
- 5
- Periods
- 10
- Rate decimal
- 0.05
- Growth factor
- 1.62889463
- Future value
- 1,628.89462678
- Interest amount
- 628.89462678
The future value of a lump-sum investment is the cash you hold after a constant periodic interest rate has compounded over a stated number of whole periods. Spreadsheets expose this identity as FV; textbooks write FV equals PV times one plus i to the n; searchers type future value calculator when they already know the present amount, the rate per period, and how many times that rate will be applied. This calculator takes those three numbers, treats the rate as percent points so five means five percent, requires periods to be a non-negative integer, and returns the compounded future value together with the growth factor and the interest earned.
What future value means and how the lump-sum identity works
The future value of a present amount is the result of applying a constant periodic interest rate a whole number of times. If the present value is PV and the periodic rate as a decimal is i, then each period multiplies the running balance by one plus i, and after n such periods the closed form is FV equals PV times one plus i raised to n. This calculator accepts the rate as percent points, so a typed five means five percent and i equals rate divided by one hundred.
When the rate is zero, the factor is one and the future value equals the present value: money that earns nothing does not grow. When the number of periods is zero, the same identity returns the original present value, which is the honest answer for a horizon that has not started. A negative rate models a constant contraction so long as the rate stays above negative one hundred percent and the factor stays positive.
The implementation does not look up a market yield, does not assume monthly versus annual compounding unless you already converted the quoted rate to the period you are counting, and does not add deposits along the way; those are other searches.
What you can do with it
Lump-sum savings and investment projections
Turn a present balance, a fixed periodic return, and an integer horizon into the future value and the interest earned for articles, planners, and landing-page widgets.
Classroom time-value-of-money checks
Let students submit present value, rate, and periods and verify the compounded future value, including the hard fail when the period count is negative or not an integer.
FAQ
How is the future value of an investment calculated?
Multiply the present value by (1 + rate/100) raised to the integer number of periods.
What happens if the number of periods is negative or not an integer?
A negative or fractional horizon is not accepted; enter a whole number of compounding periods, zero or more. Failed validation is not billed.
Is the rate a percent or a decimal fraction?
Enter rate as percent points per period, not as a decimal fraction — five means five percent per period, not 0.05. The engine divides by one hundred before raising the factor.
What do a zero rate and zero periods return?
A zero rate leaves the present value unchanged because the growth factor is one. Zero periods also returns the original present value, which is the honest answer for a horizon that has not started. A negative rate models contraction, as long as the rate is greater than −100% so that 1 + rate/100 stays positive.
Do I need to convert an annual rate if I count months?
Yes. The rate must match the period you count. If your periods are months, enter the monthly rate, not the yearly one, because the tool does not assume monthly or annual compounding on its own.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/fin/future-value \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"present_value":1000,"rate":5,"periods":10}'const res = await fetch("https://api.kit.forhosting.com/fin/future-value", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"present_value": 1000,
"rate": 5,
"periods": 10
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/fin/future-value",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"present_value": 1000,
"rate": 5,
"periods": 10
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/fin/future-value", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"present_value":1000,"rate":5,"periods":10}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"present_value":1000,"rate":5,"periods":10}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/fin/future-value", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"present_value": 1000,
"rate": 5,
"periods": 10
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "fin.future_value",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
A negative or non-integer period count fails with invalid_input instead of inventing a reverse-time or intra-period story.
What future value means and how the lump-sum identity works
A worked case of one thousand at five percent per period for ten periods has growth_factor 1.62889463 and future_value 1628.89462678 after half-up rounding to eight decimals, so the interest earned is 628.89462678.
Input contract, response shape, and error behaviour
Pair the result with your own contribution schedule if you need deposits along the way; start here when the product question is a transparent lump-sum future value for a page, a worksheet, or a batch of scenarios that already share one rate and one integer horizon. POST a JSON body with three required finite numbers: present_value (the lump sum today; aliases pv, principal, amount), rate (the interest rate per period as a percent such as five for five percent; aliases interest_rate, i, rate_percent, periodic_rate), and periods (the compounding count n, a non-negative integer; aliases n, nper, number_of_periods). Each field may arrive as a JSON number or as a numeric string. Missing fields, empty strings, booleans, and non-finite values fail with invalid_input naming the field and are not billed. If rate is less than or equal to negative one hundred percent, one plus i is not positive and the power is not a useful real factor, so that case is invalid_input as well. On success the body echoes present_value, rate and periods; reports rate_decimal and growth_factor rounded half-up to eight decimals; returns future_value and interest rounded the same way; and includes a short formula string restating FV equals PV times (1 + rate/100) to the power periods.
Where a future value calculator earns its keep
Educators teaching the time value of money can seed classroom examples that show one thousand at five percent for ten periods versus the simple-interest alternative PV times one plus i times n, and can demonstrate the hard fail when someone types a negative period count or a fractional n. Failed validation does not consume balance. Product and finance teams reconciling a stored present value against a quoted rate can post the same three numbers the product already stores and quote a stable future_value with an eight-decimal contract. Because the implementation is tier A parse, every successful call costs the published $0.002 base price with no model tokens and no outbound network. Keep the rate above negative one hundred percent, keep periods a non-negative integer, pin the rounded future_value in tests, and you get reproducible future-value results for widgets, CMS embeds, and edge workers without standing up a spreadsheet service of your own.
Integration use cases
Product and finance scenario tables
Compare two or three stored rates over the same whole-period horizon and pin a stable future_value contract in tests without opening a spreadsheet for each row.
Technical questions
What does the future value calculator cost?
The browser tool is free. API requests use prepaid balance at $0.002 per successful call; invalid input is not billed.