Equilibrium yield calculator
See how close a reversible reaction gets to full conversion: 75 mol of product at equilibrium out of a theoretical maximum of 100 mol is a 75% equilibrium yield, and 12.5 g out of 25 g is 50%. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Equilibrium amount
- 75
- Theoretical maximum
- 100
- Equilibrium yield pct
- 75
- Yield fraction
- 0.75
- Precision
- 10
This equilibrium yield calculator reports how much of the theoretical maximum product is present when a reversible reaction sits at equilibrium. You supply the product amount at equilibrium and the theoretical maximum product amount that would form if the reaction went fully to completion under the same basis, both in the same unit such as moles or grams. The engine divides the equilibrium amount by the theoretical maximum and multiplies by one hundred to return the equilibrium yield percentage, along with the unitless yield fraction. Classic classroom checks include seventy-five moles of product at equilibrium with a theoretical maximum of one hundred moles, which yields seventy-five percent, and twelve and a half grams of product at equilibrium with a twenty-five gram maximum, which yields fifty percent. The engine uses only finite deterministic arithmetic with no network calls, no sampling, and no date-dependent shortcuts.
What equilibrium yield tells you
Equilibrium yield is the percentage of the theoretical maximum product amount that is actually present when a reversible reaction reaches equilibrium under a stated set of conditions. Unlike a full equilibrium constant solve, this page assumes you already know both numbers: how much product is observed or calculated at equilibrium, and how much product would form if the reaction went completely to products with the same stoichiometric basis and starting material inventory.
Dividing equilibrium amount by theoretical maximum produces a unitless yield fraction between zero and one for ordinary incomplete equilibria, and multiplying by one hundred produces the equilibrium yield percentage used in textbooks, process summaries, and lab write-ups. Zero equilibrium product with a positive theoretical maximum is allowed and yields zero percent, which is the correct limit when no product is present at equilibrium.
Where equilibrium-yield calculation fits in study, lab work, and software
Students meet equilibrium-yield problems when a textbook contrasts complete conversion with the product inventory at equilibrium, when a homework set already states both amounts and asks for the percentage of theoretical maximum achieved, or when a contest problem expects a clear numeric yield before discussing K, temperature, or pressure effects. Teachers can pre-generate answer keys for modest decimal amounts without trusting opaque apps that confuse equilibrium yield with percent yield after isolation or with conversion defined only on the limiting reactant.
Lab technicians and process chemists use the same closed form when equilibrium composition has been measured or modeled and the theoretical completion amount is known from stoichiometry: divide, scale to percent, and report how close the system sits to full conversion under those conditions. Developers call the same contract from scripts to seed deterministic test vectors for chemistry tutors, to normalize user-entered equilibrium parameters before a lab notebook export, or to satisfy programming-challenge statements that demand an equilibrium yield percentage rather than a hand-waved sketch.
What you can do with it
Homework and equilibrium-yield checks
Convert known equilibrium product amount and theoretical maximum into equilibrium yield percentage before discussing K or Le Chatelier effects.
Lab reports and education software
Report percent of theoretical maximum at equilibrium in lab notebooks, tutoring UIs, and automated worksheet generators.
FAQ
What does the equilibrium yield calculator cost?
It is free in your browser on this page.
What happens if the theoretical maximum is zero?
A zero theoretical maximum makes the ratio undefined (division by zero).
Does this tool solve for equilibrium composition from K?
No. You must already know the equilibrium product amount and the theoretical maximum. Use an equilibrium-constant or ICE-table tool for composition solves.
Why are results rounded to a precision?
Default precision is 10 decimal places; you can set precision from 0 to 15.
Can the equilibrium yield be above 100%?
Yes, the result is shown as calculated when the equilibrium amount is larger than the stated maximum. That usually means the maximum was understated or the two amounts use different bases, so check both before reporting it.
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/chem/equilibrium-yield \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"equilibrium_amount":75,"theoretical_maximum":100}'const res = await fetch("https://api.kit.forhosting.com/chem/equilibrium-yield", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"equilibrium_amount": 75,
"theoretical_maximum": 100
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/chem/equilibrium-yield",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"equilibrium_amount": 75,
"theoretical_maximum": 100
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/chem/equilibrium-yield", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"equilibrium_amount":75,"theoretical_maximum":100}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"equilibrium_amount":75,"theoretical_maximum":100}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/chem/equilibrium-yield", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"equilibrium_amount": 75,
"theoretical_maximum": 100
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "chem.equilibrium_yield",
"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.
Limits
max_abs_value | 1000000000000000 |
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 equilibrium yield means and what the response contains
This calculator returns the validated equilibrium_amount and theoretical_maximum, the derived yield_fraction and equilibrium_yield_pct, the precision used, a method tag equilibrium_yield, and a short formula reminder so API clients and worksheets can assert on the same closed form. There is no concentration-to-K path, no ICE table solver, no stoichiometric theoretical-yield builder from limiting reactant, and no experimental isolation percent-yield mode that mixes measured mass with theoretical mass under different labels: the engine either applies the ratio inside the supported numeric range or rejects the input with invalid_input. Rejected cases include missing required fields, non-finite values, magnitudes above the documented ceiling, negative equilibrium amount, and any theoretical maximum that is zero or non-positive, because a zero maximum makes the ratio undefined as division by zero.
How amounts are read, validated, and kept reproducible
Both values must be finite numbers within the documented absolute magnitude ceiling; the equilibrium amount must not be negative, and the theoretical maximum must be strictly positive so the division is defined. Optional leading plus signs and scientific notation on numeric strings are allowed when they parse as finite decimals; embedded spaces and non-numeric tokens are rejected. Values above one hundred percent are returned as computed when the equilibrium amount exceeds the stated maximum, which can happen if the maximum was understated or the amounts use inconsistent bases; the engine does not silently clamp. The preferred field for product present at equilibrium is equilibrium_amount, but aliases eq_amount, equilibrium, amount_eq, n_eq, and equilibriumAmount are accepted so spreadsheets, query strings, and typed forms can reuse the same contract. The theoretical maximum product amount uses theoretical_maximum with aliases max_amount, theoretical_max, amount_max, n_max, and theoreticalMaximum. An optional precision field, with aliases decimals and dp, chooses how many decimal places to expose for the numeric outputs, defaulting to ten and capped at fifteen so JSON goldens stay stable across runs and locales. Computation forms yield_fraction as equilibrium_amount divided by theoretical_maximum, then equilibrium_yield_pct as yield_fraction times one hundred. Pair the free browser run on this page with the priced API when you need the identical mathematical result inside an automated pipeline without re-implementing the percentage conversion yourself.
Where equilibrium-yield calculation fits in study, lab work, and software
Product and education tools use the endpoint when a learner types equilibrium amount and theoretical maximum and the UI must show equilibrium_yield_pct with a clear intermediate yield_fraction. On this page the work runs entirely in your browser; through the API each successful lookup costs $0.002, failed validation is not charged, and nothing is stored after the response returns. That split — free interactive exploration and a priced, identical API — matches the rest of the KIT tier-A catalog and lets you move from a classroom demo to an automated pipeline without changing the mathematical result. Pair it with equilibrium-constant or theoretical-yield helpers when you need related chemistry quantities, and with other science endpoints when you are building a small lab of free, deterministic equilibrium calculators.
Integration use cases
Deterministic test fixtures
Generate reproducible equilibrium_yield_pct and yield_fraction for unit tests, chemistry tutors, and CI assertions on equilibrium conversion.
Technical questions
How is equilibrium yield computed?
yield_fraction = equilibrium_amount / theoretical_maximum, and equilibrium_yield_pct = yield_fraction × 100. Both amounts must use the same unit.