Theoretical yield calculator
With 2.5 moles of limiting reagent and two moles of product per mole consumed, the theoretical yield is 5 moles. Give the ratio directly or the two coefficients from the balanced equation and get the most product a complete reaction could form. Free in your browser.
- Free
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- Your data stays on your device
Run — free
Worked example
- Moles
- 2.5
- Ratio
- 2
- Theoretical yield
- 5
- Ratio source
- ratio
Theoretical yield is the maximum amount of product you can expect when a reaction runs to completion with no side paths and perfect recovery. In mole form it is simply the moles of limiting reactant multiplied by the stoichiometric ratio of product to that reactant from the balanced chemical equation. This capability accepts those two pieces of data—or the two balanced coefficients that define the ratio—computes the theoretical product yield with deterministic arithmetic, and rejects negative moles so homework checkers and lab pipelines never treat an impossible inventory as a valid start.
What theoretical yield means and which numbers to send
Start from a balanced equation and identify the limiting reactant—the reagent that runs out first and therefore caps how much product can form. Convert that reactant to moles if you began from a mass, then read the stoichiometric coefficients of the product and of that reactant. The ratio product coefficient divided by reactant coefficient is how many moles of product form per mole of limiting reactant consumed.
Negative moles are invalid input because a starting amount below zero is not a physical inventory for a theoretical-yield problem. Zero moles is allowed and simply yields zero product, which is the correct limit when no limiting reactant is present. Classroom examples include two point five moles of limiting reagent with a two-to-one product-to-reactant ratio giving five moles of product theoretical yield, or coefficients two and one for the same result when you prefer to send the balanced numbers separately.
What you can do with it
Lab prep and stoichiometry sheets
Technicians and teaching assistants compute expected product moles from a known limiting inventory before converting to mass for labeling prep sheets.
FAQ
What happens if moles are negative?
Negative moles are not a valid starting inventory for theoretical yield; the field must be non-negative. Validation failures are not charged.
Is the theoretical yield calculator free?
The browser tool runs free on your device.
Does this return percent yield or mass of product?
No. It returns theoretical product moles only. Convert to grams with molar mass in your pipeline, and compute percent yield separately as actual over theoretical times one hundred.
Can I enter the coefficients instead of the ratio?
Yes. Give the product coefficient and the limiting reactant's coefficient, and the ratio is worked out for you. Coefficients two and one with 2.5 moles give the same 5 moles as a ratio of two.
What does theoretical yield mean?
It is the most product you could expect if the reaction ran to completion with no side reactions and perfect recovery. Real lab results fall below it, which is why it serves as the reference for percent yield.
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/theoretical-yield \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"moles":2.5}'const res = await fetch("https://api.kit.forhosting.com/chem/theoretical-yield", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"moles": 2.5
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/chem/theoretical-yield",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"moles": 2.5
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/chem/theoretical-yield", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"moles":2.5}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"moles":2.5}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/chem/theoretical-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
{
"moles": 2.5
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "chem.theoretical_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.
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
Students, tutoring apps, LIMS scripts, and prep-sheet generators can pin the same JSON in tests without embedding a full chemistry CAS.
What theoretical yield means and which numbers to send
Send the required field moles as a finite non-negative number, with optional aliases moles_limiting, limiting_moles, or n_limiting so client code can speak laboratory English. Provide either the field ratio (or stoichiometric_ratio, stoich_ratio, product_per_reactant) as a positive number, or both product_coeff and reactant_coeff as positive balanced-equation coefficients so the engine derives the same ratio. Identical inputs always produce identical JSON because the path is pure arithmetic with no network, no model, no random seed, and no wall clock.
Reading the response: yield, ratio, coefficients, and formula
Validation failures such as negative moles mention that negative moles are not allowed so students can correct a sign error without reading a stack trace. On success the response echoes moles of limiting reactant, the effective ratio after stable rounding, optional product_coeff and reactant_coeff when you supplied them, and theoretical_yield as the product moles expected at one hundred percent conversion. The unit field is always mol so UIs can label the number without guessing, formula restates theoretical_yield equals moles_limiting times product_coeff over reactant_coeff for quick display, and ratio_source reports whether the ratio came from the direct ratio field or from the coefficient pair. The method label is always stoichiometric_ratio so downstream routers can branch without sniffing shapes. Use theoretical_yield alone when a form only needs the answer cell; use moles and ratio together when a worked solution sheet must reprint the inputs next to the result; use the coefficient fields when grading software checks that students entered the balanced numbers correctly before the multiplication. Missing both ratio and coefficient pairs, non-finite numbers, and non-positive ratios or coefficients also raise invalid_input and are not charged after the engine rejects the request.
API usage, pricing, lab workflows, and practical limits
Call the free in-browser theoretical yield calculator for homework checks, lecture demos, and quick bench planning without installing a spreadsheet formula library or a computer-algebra system. Multi-step syntheses are not modeled as a chain inside one call; run the identity once per balanced step using the theoretical product of the previous step as the next limiting inventory when that is your process model. Source inputs follow the same retention rules as other KIT parse items. Send a JSON body with moles and either ratio or both product_coeff and reactant_coeff as numbers or numeric strings. Use the prepaid API when a tutoring platform, coding-assessment sandbox, LIMS integration, or curriculum generator needs a stable contract under KIT balance at $0.002 per successful item; validation failures never consume balance after the engine rejects the request. Pair this endpoint with a molar mass helper in your own pipeline when the next step is converting theoretical moles into expected grams, or with a percent-yield step when you already measured actual product mass—this capability intentionally stops at theoretical moles so each SEO intent stays focused. Authors shipping SDKs can map moles, ratio, and theoretical_yield into labeled inputs Limiting moles, Stoich ratio, and Theoretical product moles—the same columns students write when they rearrange stoichiometry tables by hand on paper.
Integration use cases
Homework and exam verification
Students enter limiting moles and the balanced ratio, compare theoretical product moles against structured JSON, and get a clear error when negative moles are submitted by mistake.
Tutoring apps and LIMS integrations
Curriculum tools and lab systems call a stable prepaid endpoint instead of reimplementing moles times ratio in every language and spreadsheet.
Technical questions
How do I calculate theoretical yield with this calculator?
Send JSON with moles set to the limiting reactant amount and ratio set to product/reactant from the balanced equation (or product_coeff and reactant_coeff). The response includes theoretical_yield in moles.
Can I send balanced coefficients instead of a single ratio?
Yes. Provide product_coeff and reactant_coeff as positive numbers; the engine sets ratio to product_coeff divided by reactant_coeff and multiplies by moles.