# Percent Yield Calculator

> Divides the actual (experimental) yield by the theoretical yield to give percent yield, plus the amount and percentage of product lost.

- Calculator id: `percent-yield` · Category: Chemistry (`chemistry`) · Tool name: `calculate_percent_yield`
- Canonical page: https://tttkmbb.com/chemistry/percent-yield · This document: https://tttkmbb.com/chemistry/percent-yield.md · JSON definition: https://tttkmbb.com/chemistry/percent-yield.json

## Purpose

Divides the actual (experimental) yield by the theoretical yield to give percent yield, plus the amount and percentage of product lost.

**Use when:** You have the theoretical yield from stoichiometry and the mass or moles actually isolated, and want the reaction's percent yield.

**Do not use when:** You still need the theoretical yield itself (compute moles of product from the limiting reagent with moles-mass first), or you want atom economy, which compares molar masses of reagents and product rather than isolated yield.

## Input

| Parameter | Type | Unit | Required | Description |
| --- | --- | --- | --- | --- |
| `actual_yield` | number |  | required | Amount of product actually obtained, in grams or moles (same unit as theoretical_yield). (min 0) |
| `theoretical_yield` | number |  | required | Maximum amount of product predicted by stoichiometry from the limiting reagent, same unit as actual_yield. (> 0) |

## Output

| Field | Type | Unit | Description |
| --- | --- | --- | --- |
| `percent_yield` | number | % | 100 × actual / theoretical. |
| `yield_fraction` | number |  | actual / theoretical. |
| `product_lost` | number |  | theoretical − actual, in the input unit. |
| `percent_lost` | number | % | 100 − percent_yield. |

## Formula

`percent_yield = 100 × actual_yield / theoretical_yield; product_lost = theoretical_yield − actual_yield`

## Data Sources

- OpenStax Chemistry 2e – 4.4 Reaction Yields — https://openstax.org/books/chemistry-2e/pages/4-4-reaction-yields (textbook, retrieved 2026-09-23)
- Wikipedia – Yield (chemistry) — https://en.wikipedia.org/wiki/Yield_(chemistry) (reference, retrieved 2026-09-23)

Data freshness: `static`. Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output.

## API

- `GET https://tttkmbb.com/api/v1/calculate/percent-yield?actual_yield=…&theoretical_yield=…`
- `POST https://tttkmbb.com/api/v1/calculate/percent-yield` with JSON body `{"inputs": {…}}`
- Response: unified envelope (`success`, `request`, `result.values`, `result.units`, `sources`, `freshness`, `timestamp`, `next_actions`, `links`); see https://tttkmbb.com/docs/response-format.md
- Schema: https://tttkmbb.com/api/v1/calculators/percent-yield · OpenAPI operationId `calculate_percent_yield` in https://tttkmbb.com/openapi.json
- Authentication: none. Rate limit: fair use, see https://tttkmbb.com/docs/rate-limits.md.

## MCP

- Server: `https://tttkmbb.com/mcp` (Streamable HTTP, JSON-RPC 2.0, no auth)
- Tool:  `run_calculator` with `{"calculator_id": "percent-yield", "inputs": {…}}`

## Example

- 4.5 g obtained of 5.0 g theoretical: inputs `{"actual_yield":4.5,"theoretical_yield":5}` → `{"percent_yield":90,"yield_fraction":0.9,"product_lost":0.5,"percent_lost":10}`
- 12.3 g obtained of 15.0 g theoretical: inputs `{"actual_yield":12.3,"theoretical_yield":15}` → `{"percent_yield":82,"product_lost":2.7}`

```
GET https://tttkmbb.com/api/v1/calculate/percent-yield?actual_yield=4.5&theoretical_yield=5
```

## Limitations

You still need the theoretical yield itself (compute moles of product from the limiting reagent with moles-mass first), or you want atom economy, which compares molar masses of reagents and product rather than isolated yield. All values are computed from the formula above; no measurement or live data is involved.

## FAQ

**Can percent yield exceed 100%?**

Not for a pure, dry product. A value above 100% indicates residual solvent, impurities or a weighing error; the calculator reports it with a note.

**Should I use grams or moles?**

Either, as long as both yields use the same unit for the same product; the ratio is identical.

## Related

- [Moles to Grams Calculator](https://tttkmbb.com/chemistry/moles-mass.md) — Convert moles of product from stoichiometry into the theoretical mass.
- [Molar Mass Calculator](https://tttkmbb.com/chemistry/molar-mass.md) — Molar mass of the product for the mass conversion.
- [Percentage Calculator](https://tttkmbb.com/math/percentage.md) — General percentage arithmetic.