Expense ratio calculator
Operating expenses of 75,000 on average assets of 10,000,000 give an expense ratio of 0.0075, or 0.75% a year. Compare share classes of the same fund by what running them actually costs. Free in your browser.
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Run — free
Worked example
- Operating expenses
- 75,000
- Average assets
- 10,000,000
- Expense ratio
- 0.0075
- Expense ratio percent
- 0.75
The fund expense ratio — searched as an expense ratio calculator, total expense ratio, or TER calculator — is the share of a mutual fund's or ETF's average assets consumed by a year's operating costs. Given total annual operating expenses and average assets under management in the same currency, the identity is expenses divided by average AUM, returned as a decimal. Advisers, analysts, and long-term savers use this figure whenever they compare two share classes or estimate the fee drag on a holding. This expense ratio calculator accepts those two amounts, rejects a zero asset base instead of dividing by zero, and returns the decimal ratio together with the equivalent percent.
What a fund expense ratio means and how the TER formula works
A fund expense ratio answers one comparison question: what share of average assets did this mutual fund, index fund, or exchange-traded fund spend on operating the vehicle during the year? Searchers who type expense ratio calculator want that quotient as a decimal, not a sales load paid once at purchase, not a portfolio-turnover percentage, and not a 12b-1 line taken in isolation.
Total annual operating expenses is the numerator: the management fee plus administration, custody, transfer agency, legal, audit, and any 12b-1 distribution that the statement of operations treats as a fund expense. Average assets under management is the denominator: the mean net assets against which those costs are scaled, typically the daily average for the fiscal year or, when a daily series is missing, the simple mean of beginning and ending net assets. The identity is expense ratio equals operating expenses divided by average assets.
A result of 0.0075 means seventy-five basis points, or seventy-five cents of every hundred dollars of average AUM, went to running the fund that year. A result of zero means the expense line you supplied is empty. The calculator does not fetch a prospectus, does not annualize a stub quarter, and does not fold brokerage commissions, bid-ask spreads, or front-end loads into the ratio unless you already included those items in the expense total.
Prefer the same currency and the same fiscal year for both inputs; mixing a calendar-year expense total with a quarter-end AUM print is not a fund TER, it is a mixed snapshot that will mislead any share-class comparison you hang on the result.
Where an expense ratio calculator earns its keep
Advisers and discount brokers use an expense ratio calculator when two share classes of the same strategy differ only in the fee line and the client needs the decimal TER before money moves. Asset-management finance teams recompute the figure from the statement of operations and the average net-asset series so the board pack matches the prospectus print, including the case of a brand-new fund whose average assets are still zero and must fail rather than print Infinity.
Educators and CFA-style homework need an oracle that divides annual operating expenses by average AUM and rejects a zero denominator the way a marking scheme does, instead of letting a spreadsheet leak Infinity into a gradebook. Failed validation is not billed. Keep average assets positive, pin the rounded decimal in tests, and you get reproducible TER figures for spreadsheets, workflow tools, and edge workers without standing up a fund-analytics library of your own.
Use this capability when you already have both the expense total and the average AUM; if you have only a headline management fee and want a load-adjusted return or a tracking-difference figure, that is a different identity and does not belong in this expense-ratio definition.
What you can do with it
Share-class TER comparison
Convert each class's annual operating expenses and average AUM into a decimal expense ratio so two share classes of the same strategy rank by fee drag, not by raw dollar costs.
Prospectus and board packs
Reproduce the fund's disclosed TER from the statement of operations and the average net-asset series, including rejection when average assets are still zero.
Classroom and CFA homework
Mark expense-ratio items with a deterministic oracle that divides operating expenses by average AUM and fails loudly on a zero asset base.
FAQ
Does this include sales loads and trading costs?
No. The identity uses annual operating expenses over average AUM. Front-end loads, redemption fees, and brokerage commissions belong in the inputs only if you already folded them into the expense total.
What counts as operating expenses?
The management fee plus administration, custody, transfer agency, legal, audit and any 12b-1 distribution fee the fund books as an expense. Use the total for the whole fiscal year, in the same currency as the assets.
What if I only have beginning and ending net assets?
Average them yourself and enter that mean as average assets. A daily average for the fiscal year is the more precise base when the fund publishes one.
Why must expenses and assets cover the same period?
Because the ratio compares a year of costs with the assets they were spent on. Mixing a calendar-year expense total with a quarter-end asset figure gives a mixed snapshot that can mislead any share-class comparison.
What happens if average assets are zero?
The calculation is refused, because dividing by a zero asset base has no answer. A brand-new fund with no measured assets cannot have an expense ratio yet; expenses of zero, on the other hand, simply give zero.
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/expense-ratio \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"operating_expenses":75000,"average_assets":10000000}'const res = await fetch("https://api.kit.forhosting.com/fin/expense-ratio", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"operating_expenses": 75000,
"average_assets": 10000000
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/fin/expense-ratio",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"operating_expenses": 75000,
"average_assets": 10000000
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/fin/expense-ratio", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"operating_expenses":75000,"average_assets":10000000}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"operating_expenses":75000,"average_assets":10000000}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/fin/expense-ratio", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"operating_expenses": 75000,
"average_assets": 10000000
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "fin.expense_ratio",
"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
What a fund expense ratio means and how the TER formula works
Average assets must be strictly greater than zero because a zero AUM base makes the TER undefined; this endpoint fails with invalid_input instead of printing Infinity.
Input contract, response shape, rounding, and error behaviour
A brand-new vehicle whose average assets have not yet been measured must fail rather than print Infinity. POST a JSON body with two required finite numbers: operating_expenses and average_assets, in the same currency and covering the same fiscal year. operating_expenses (aliases total_operating_expenses, annual_operating_expenses, expenses, and total_expenses) must be finite and greater than or equal to zero. average_assets (aliases aum, average_aum, assets_under_management, and average_assets_under_management) must be a finite number strictly greater than zero because the expense ratio divides operating expenses by average AUM. If you only have beginning and ending net assets, average them yourself and pass the mean as average_assets. Missing fields, empty strings, non-finite values, a negative expense stock, and a zero or negative asset base fail with invalid_input naming the issue, and those failures are not billed. On success the body echoes both inputs, returns expense_ratio as the decimal quotient rounded to twelve places, expense_ratio_percent as one hundred times that quotient, and a formula string restating the identity. Example: operating expenses of seventy-five thousand against average assets of ten million yields expense_ratio 0.0075 and expense_ratio_percent 0.75. Example: operating expenses of one hundred against average assets of three hundred yields a repeating decimal rather than a silent empty payload. Pair the ratio with your own share-class notes if the memo needs a cheap or expensive flag; this endpoint computes the TER only and does not invent a product verdict, a net-of-fee return, or a tracking-error figure.
Technical questions
How is a fund expense ratio calculated?
Send finite numbers operating_expenses (≥ 0) and average_assets (> 0) in the same currency. The API returns expense_ratio = operating_expenses / average_assets as a decimal, plus the same figure as a percent.
What happens if average assets are zero?
The task fails with invalid_input. A fund expense ratio cannot divide by a zero AUM base, so the request is rejected and is not billed.
Is the result a decimal or a percent?
The primary field expense_ratio is a decimal (0.0075 for a 0.75% TER). expense_ratio_percent is the same quotient multiplied by one hundred for display.
What does the expense ratio calculator cost?
The browser tool is free. API requests use prepaid balance at $0.002 per successful call; invalid input is not billed.