UK coin weight calculator
Sixteen coins from 1p to £2 weigh 98.73 grams together, using official Royal Mint masses from 3.56 g for a penny to 12.00 g for a £2 coin. Enter how many of each you hold; the result is weight, not face value. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Penny
- 4
- Two pence
- 2
- Five pence
- 1
- Ten pence
- 3
- Twenty pence
- 2
- Fifty pence
- 1
- Total coins
- 16 g
- Total weight g
- 98.73
British circulating coins have official masses in grams, so the weight of a jar, a till bag, or a pocketful of change is a straight sum of counts times those published masses. This UK coin weight calculator accepts how many 1p, 2p, 5p, 10p, 20p, 50p, £1, and £2 pieces you have, multiplies each count by the current Royal Mint specification, and returns the combined weight in grams together with the total number of coins. Omitted denominations default to zero, so a pocket of only twenty-pence pieces still works. There is no live metal quote, no network, and no face-value conversion: the result is mass, not money.
What circulating UK coins weigh and how the total is summed
The eight circulating United Kingdom coins have fixed legal masses published by the Royal Mint for current issues. A copper-plated steel penny (1p) weighs 3.56 grams. A two-pence piece weighs 7.12 grams, twice the penny, a leftover of the 1971 decimal design that paired the 1p and 2p as a mass family.
The nickel-plated steel five-pence coin is 3.25 grams and the ten-pence coin is 6.50 grams. The cupro-nickel twenty-pence piece is 5.00 grams. The heptagonal fifty-pence piece is 8.00 grams.
The current twelve-sided one-pound coin, which replaced the round pound in 2017, is 8.75 grams. The bi-metallic two-pound coin is 12.00 grams. This calculator multiplies each count you supply by that official mass and adds the eight products.
The combined weight is the mass of the set in grams, not its face value in pounds and pence. A jar of mixed change is therefore a sum of integer counts times published grams, which is why a handful of fifty-pence coins can outweigh a larger stack of pennies of smaller mass. Counts may be zero or omitted, and omitted fields are treated as zero so you only fill the denominations you actually hold.
Where a UK coin weight calculator earns its keep
Charity counters, school fundraising, and small-shop cash-up need a live UK coin weight calculator that turns a sorted pile into a gram total without forcing visitors to paste a spreadsheet. Educators teaching decimal coinage can seed classroom examples that show why twenty 1p coins (71.20 g) weigh the same as ten 2p coins, without standing up a Royal Mint data vendor. Failed validation does not consume balance.
Keep every count a non-negative integer, pin the rounded gram field in tests, and you get reproducible bag weights for widgets, LMS modules, and edge workers without a live metals feed of your own.
What you can do with it
Charity and fundraising coin bags
Count the 1p through £2 pieces in a sorted jar and read the combined grams before a bank bag or postage limit is exceeded.
Till cash-up and float checks
Weigh a drawer of mixed sterling coins from denomination counts so the closing float’s mass matches the counted pieces, without converting to face value.
FAQ
How is the total weight of UK coins calculated?
Each denomination count is multiplied by its current Royal Mint mass in grams (1p 3.56, 2p 7.12, 5p 3.25, 10p 6.50, 20p 5.00, 50p 8.00, £1 8.75, £2 12.00) and the eight products are added. The combined mass is rounded half-up to two decimal places.
What happens if a coin count is negative?
A negative count is not a weighable set and is not billed.
Do I have to send every denomination?
No. Every count is optional and defaults to zero. Send only the coins you hold; omitted fields do not change the total.
Is this the old round pound or the 12-sided £1?
The current 12-sided pound at 8.75 g, introduced in 2017. The withdrawn round pound (9.50 g) is not circulating and is not in the table.
Why do ten 2p coins weigh the same as twenty 1p coins?
Because a 2p piece weighs 7.12 g, exactly twice the 3.56 g penny, a leftover of the 1971 decimal design that paired the two as a mass family. Both piles come to 71.20 g.
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/uk-coin-weight \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"penny":4,"pence_1":0}'const res = await fetch("https://api.kit.forhosting.com/fin/uk-coin-weight", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"penny": 4,
"pence_1": 0
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/fin/uk-coin-weight",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"penny": 4,
"pence_1": 0
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/fin/uk-coin-weight", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"penny":4,"pence_1":0}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"penny":4,"pence_1":0}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/fin/uk-coin-weight", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"penny": 4,
"pence_1": 0
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "fin.uk_coin_weight",
"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_count | 10000000 |
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
Negative counts are rejected as invalid_input because you cannot hold minus three pennies.
What circulating UK coins weigh and how the total is summed
A negative count is physically meaningless, and the task fails with invalid_input instead of inventing a negative mass.
Input contract, response shape, and error behaviour
If any count is negative the task fails with a message that the field must not be negative — those failures are not billed, because minus three pennies is not a weighable set. Example: four pennies, two 2p, one 5p, three 10p, two 20p, one 50p, two pounds and one two-pound coin weigh 98.73 grams across sixteen pieces. POST a JSON body with up to eight non-negative integer counts: penny (1p at 3.56 g; aliases pence_1, one_pence, p1), two_pence (2p at 7.12 g; aliases pence_2, twopence, p2), five_pence (5p at 3.25 g; aliases pence_5, p5), ten_pence (10p at 6.50 g; aliases pence_10, p10), twenty_pence (20p at 5.00 g; aliases pence_20, p20), fifty_pence (50p at 8.00 g; aliases pence_50, p50), one_pound (£1 at 8.75 g; aliases pound, pound_1, gbp1), and two_pound (£2 at 12.00 g; aliases pounds_2, two_pounds, gbp2). Every field is optional and defaults to zero when omitted, empty, or blank, so a request that only names two_pound still weighs a bag of two-pound coins. Each count may arrive as a JSON integer or as a numeric string. Non-finite values, fractional counts, and values above ten million fail with invalid_input naming the field. On success the body echoes the eight counts (zeros included, so the contract is stable), total_coins (the sum of the eight integers), total_weight_g (the combined mass rounded half-up to two decimal places), unit as the string g, and a formula string restating the eight-term identity. Pair the mass with your own postage or bag-limit table if you need a shipping check; this endpoint reports grams only and does not emit face value, metal composition, or plots.
Where a UK coin weight calculator earns its keep
Bank-bag and postage workflows can call the same pure module from the browser for a free preview and from the API when storing a till lot, so the mass a volunteer saw on a landing page matches the mass stored after they save a bag. The contract is deliberately small: eight counts in, combined grams out, so clients can wrap it in their own bag-limit and postage tables without fighting hidden state or a currency API.
Integration use cases
Classroom decimal-coinage demos
Show that twenty pennies match ten 2p coins by mass, using the same Royal Mint table the API and the free widget share.
Technical questions
What does the UK coin weight calculator cost?
The browser tool is free. API requests use prepaid KIT balance at $0.002 per successful call; invalid input is not billed.