Epoxy resin mix calculator
A 2:1 epoxy for a 100 ml mold splits into two thirds resin and one third hardener: enter the total amount and the ratio printed on the bottle, by volume or by weight, and get both amounts with their percentages. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Total mold volume
- 100 ml
- Resin parts
- 2
- Hardener parts
- 1
- By
- volume
- Parts total
- 3 ml
- Ratio
- 2:1
- Resin amount
- 66.6666666667
- Hardener amount
- 33.3333333333
Epoxy and polyester resin systems almost always ship as a resin plus a hardener that must be combined in a fixed ratio before the mold is poured. Whether the manufacturer prints two-to-one by volume, one-hundred-to-forty-five by weight, or another positive pair of parts, the practical question is the same: given the mold cavity volume or the total batch size you want to mix, how many millilitres or grams of each component do you measure? This epoxy resin mix calculator accepts a positive total amount and a positive resin-to-hardener ratio, then returns each component amount as a strict proportional split of that total.
How resin and hardener amounts are computed from a ratio
Start from a total mix amount V that matches your mold volume or the batch size you intend to stir. The manufacturer ratio is written as R parts resin to H parts hardener, either by volume or by weight. Both parts must be strictly positive finite numbers; a zero or negative side is not a valid system and is rejected immediately.
The total number of parts is P equals R plus H. The resin amount is then V times R divided by P, and the hardener amount is V times H divided by P. Those two quantities always add back to V within ordinary floating-point precision, so you can check conservation of the batch.
A classic two-to-one by volume system for a one-hundred millilitre mold therefore needs about sixty-six point six seven millilitres of resin and thirty-three point three three millilitres of hardener. A one-hundred-to-forty-five by weight system for a two-hundred-ninety gram pour needs two hundred grams of resin and ninety grams of hardener. The calculator also reports fractions and percentages so labels, worksheets, and machine mixers can assert the same split without re-deriving the arithmetic.
The optional by field only documents whether the ratio is interpreted by volume or by weight; the closed-form split is identical once the user measures both components in a consistent unit system. Optional unit text such as ml or g is echoed for display and never converted.
Where epoxy resin mix calculators show up in real work
Hobby makers casting coasters, river tables, jewelry blanks, and figurine molds constantly recompute resin and hardener for irregular cavity volumes; a single trusted oracle that returns both amounts from any positive ratio speeds the pour list and reduces wasted mix. Retail craft shops and resin-kit brands need floor demos and website configurators that accept the printed ratio on the bottle and a mold volume in millilitres without mental arithmetic errors.
Industrial small-batch shops writing job tickets for epoxy coatings, potting compounds, and composite layups encode the same proportional split when the technician scales a datasheet ratio to a given pot size. Content creators building how-to videos, blog gear guides, and printable pour charts need bulk tables of common mold sizes times common two-to-one and one-hundred-to-X systems without re-implementing validation in every spreadsheet.
If you later need density-based volume-to-mass conversion, pot-life timers, exotherm estimates, or multi-part systems beyond resin plus hardener, treat those as separate search intents and landings rather than overloading this epoxy resin mix calculator page.
What you can do with it
Mold pour planning
Enter cavity volume and the bottle ratio (2:1, 1:1, 100:45, …) to get exact resin and hardener amounts before you open the cups.
Retail and workshop demos
Show customers both component amounts for any positive ratio and mold size without mental math or spreadsheet mistakes on the floor.
FAQ
How does the epoxy resin mix calculator work?
Both ratio parts and the volume must be strictly positive.
Can I use a by-weight ratio instead of by-volume?
The arithmetic is the same proportional split; measure resin and hardener in a consistent mass unit such as grams.
What happens if the ratio is zero or negative?
Non-positive volume or ratio parts are rejected so invalid recipes never look like successful mixes.
What does it cost?
The browser tool is free and runs locally.
How much resin and hardener do I need for a 100 ml mold at 2:1?
Two thirds of the 100 ml is resin and one third is hardener. The two amounts always add back to the total you entered, so you can check that nothing was lost in the split.
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/hobby/resin-mix \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"volume":100,"resin_parts":2,"hardener_parts":1}'const res = await fetch("https://api.kit.forhosting.com/hobby/resin-mix", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"volume": 100,
"resin_parts": 2,
"hardener_parts": 1
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/hobby/resin-mix",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"volume": 100,
"resin_parts": 2,
"hardener_parts": 1
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/hobby/resin-mix", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"volume":100,"resin_parts":2,"hardener_parts":1}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"volume":100,"resin_parts":2,"hardener_parts":1}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/hobby/resin-mix", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"volume": 100,
"resin_parts": 2,
"hardener_parts": 1
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "hobby.resin_mix",
"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
Zero, negative, or non-finite ratio parts fail with a clear invalid_input error so bad recipes never look like successful pours.
What you send and what you get back
Send volume as a positive number for the mold total or batch size. Optional by may be volume or weight and defaults to volume. Optional unit is a short display string like ml, g, or fl oz. Classic checks include one hundred millilitres at two-to-one by volume, two hundred ninety grams at one-hundred-to-forty-five by weight, and a deliberate zero hardener part that must throw rather than invent free product. Send the ratio either as resin_parts and hardener_parts, or as a ratio string such as two colon one or one hundred colon forty-five. Aliases include mold_volume, total, and amount for the total; resin and hardener for the parts; mix_ratio for the string form; and measure or basis for the by field. Missing required fields, non-numeric strings, NaN, Infinity, non-positive volume, non-positive ratio parts, and malformed ratio strings fail with invalid_input and are not charged. On success the response echoes cleaned volume, resin_parts, hardener_parts, parts_total, a printable ratio label, by, and unit, plus resin_amount, hardener_amount, resin_fraction, hardener_fraction, resin_percent, hardener_percent, a human summary line, the formula text, and method resin_mix_ratio. Pricing for successful API calls is the published base of $0.002 per item; validation failures do not consume prepaid balance.
Where epoxy resin mix calculators show up in real work
Because this capability is a pure parse engine, API pricing is the published base of $0.002 per successful item and failed validation does not consume balance.
Integration use cases
Batch tickets and fixtures
Bulk-produce resin/hardener splits for job tickets, lesson answer keys, and regression tests with hard invalid_input on non-positive ratios.
Technical questions
How do I enter a 2:1 or 100:45 ratio?
Send resin_parts and hardener_parts as numbers, or send ratio as a string like "2:1" or "100:45". Either form is accepted.