UK100 Margin Calculator
Indices
Margin is the portion of your balance your broker sets aside while a UK100 position is open — it isn't a fee or a cost, it's held and released back to you when the trade closes. This calculator uses UK100's own real contract size and margin rate rather than a generic leverage assumption.
How is required margin calculated for UK100?
Say a trader has a $10,000 account and opens 1.00 lot of UK100 short (sell) at 10,713.78, with a 2.00% margin requirement.
Free margin — what's left available for other trades — is $10,000 minus $214.28, which is $9,785.72. Margin level (equity divided by used margin) starts at 4,666.9%.
What is the difference between margin and leverage?
Leverage is usually quoted as a ratio set by your account (like 1:100) — a cap on how large a position you're allowed to open relative to your balance, not a target. Margin is the actual dollar amount reserved for a specific position: on this $10,000 account, one lot of UK100 ties up roughly $214.28 in margin, an effective leverage of about 1.1:1 — typically far below the account's maximum allowed leverage.
What is a margin call and how do I avoid one?
Now say price moves 64 points against the position, to 10,777.78.
Margin level has dropped from 4,666.9% to 4,627.2%. If it keeps falling toward your broker's stop-out threshold (commonly 50-100%, broker-dependent), positions start getting force-closed automatically, starting with the largest loss — a margin call is the warning that usually comes before that. Keeping free margin well above zero, not just at the moment you open a trade, is what avoids this.
How margin works on UK100
The FTSE 100 tracks the 100 largest companies listed on the London Stock Exchange, many of which earn most of their revenue outside the UK. It is most active from the London open; the cash market is closed in the Asian session, so overnight moves follow other markets.
Margin is a deposit your broker holds while the trade is open, not a fee, and you get it back when the position closes. On this page one standard lot of UK100 has a contract size of 1, and the reference margin requirement is 0.5%, which is the same as leverage of 1:200.
Worked example: margin for one standard lot of UK100
The figures use rounded reference prices for illustration, not a live quote.
- Position value for 1.00 lot: 1.00 lot × 1 contract × 10,700.0 × 1.32 GBP-to-USD = $14,124.
- Margin at 1:10: $14,124 ÷ 10 = $1,412.40.
- Margin at 1:30: $14,124 ÷ 30 = $470.80.
- Margin at 1:200: $14,124 ÷ 200 = $70.62.
- Margin at 1:500: $14,124 ÷ 500 = $28.25.
Higher leverage lowers the margin you must post, but the position value stays $14,124, so a 40 point move still costs $52.80 per lot at every leverage setting.
Margin for smaller UK100 positions
- 0.10 lots: 0.10 lot × 1 contract × 10,700.0 × 1.32 GBP-to-USD = $1,412; margin at 1:200 = $1,412 ÷ 200 = $7.06.
- 0.01 lots: 0.01 lot × 1 contract × 10,700.0 × 1.32 GBP-to-USD = $141; margin at 1:200 = $141 ÷ 200 = $0.71.
- 1.89 lots (the size from a $10,000 account risking 1%): 1.89 lot × 1 contract × 10,700.0 × 1.32 GBP-to-USD = $26,694; margin at 1:200 = $26,694 ÷ 200 = $133.47.
Margin level on a $10,000 account: a full scenario
Assume a $10,000 account with no other open trades, buying 1.89 lots of UK100 at 10,700.0 with a stop 40 points below the entry.
- Position value: $26,694.
- Used margin at 1:200: $26,694 ÷ 200 = $133.47.
- Free margin on opening: $10,000 − $133.47 = $9,866.53.
- Margin level on opening: $10,000 ÷ $133.47 × 100 = 7,492%.
- Floating loss if price falls to the stop: 1.89 × 40 × $1.32 = $99.79.
- Equity at the stop: $10,000 − $99.79 = $9,900.21, so the margin level is $9,900.21 ÷ $133.47 × 100 = 7,418%.
Brokers watch the margin level and close positions automatically when it falls below a threshold that differs by broker, often somewhere around 50% to 100%. For the margin level to reach 100% here, equity would have to fall to $133.47, a loss of $9,866.53, which is 9,866.53 ÷ (1.89 × $1.32) = 3,955 points, taking price to 6,745.0. A properly sized stop closes the trade long before that, which is why margin trouble usually comes from oversized positions, not from leverage itself.
Leverage and position size are not the same thing
Position size is the number of lots, and it should come from your risk and stop distance (see the UK100 lot size calculator). Leverage only sets the margin for that size. Moving this account from 1:200 to 1:30 would raise the margin on 1.89 lots from $133.47 to $26,694 ÷ 30 = $889.80, which still fits inside the $10,000 equity, so the same 1.89 lots could be opened. The effective leverage of the position, $26,694 ÷ $10,000 = 2.7×, did not depend on the ceiling at all.
Verify UK100 margin with your broker
The 0.5% requirement and the contract size of 1 are reference values. Regulators, account types and brokers set different leverage caps, and some brokers raise the requirement around news or for large positions, so check the margin shown in your platform's order ticket before relying on this page. For the general concept, see margin in finance, margin calls and leverage on Wikipedia.
More tools for UK100
- Turn a risk amount and a stop distance into a lot size with the UK100 lot size calculator.
- Check what one point is worth per lot with the UK100 pip value calculator.
- Work out the result of a finished trade with the UK100 profit and loss calculator.
- Compare risk and reward before entering with the UK100 risk reward ratio calculator.
- Mark support and resistance from yesterday's range with the UK100 pivot points calculator.
- Compare a similar instrument: GBPUSD margin calculator.
- Compare a similar instrument: DJ30 margin calculator.
Conclusion
This math only holds if 1 units per lot and a 2.00% requirement are actually your own broker's real numbers for UK100 — margin requirements vary by broker and can change with volatility. Always confirm your own platform's real figures (Market Watch, then Specification) before relying on a suggested margin number for a real trade. See what margin actually is and how brokers use it, Wikipedia's entry on margin in finance for the underlying concept, and a real two-position MT4 example showing free margin in practice.
Contract specification
Point value and minimum lot step vary by broker on index/CFD instruments — a mismatch here is a common, avoidable cause of an unexpectedly large loss. Confirm this instrument's contract specification in your platform before sizing a real trade.
Frequently asked questions
Why might my broker's margin requirement differ from this calculator's default?
Margin requirements are set per broker and can change with volatility, account type, or regulatory tier.
Does leverage change how many lots of UK100 I should trade?
No. Lot size comes from your risk amount and stop distance, and leverage only sets how much margin that size needs. For 1.89 lots of UK100 the margin is $133.47 at 1:200 and $889.80 at 1:30, yet the risk at a 40 point stop is $99.79 in both cases.
How much margin do I need for 0.10 lots of UK100?
On the reference figures, 0.10 lot × 1 contract × 10,700.0 × 1.32 GBP-to-USD = $1,412. At 1:200 the margin is $1,412 ÷ 200 = $7.06.
What is margin level, and what happens if it gets too low on UK100?
Margin level is equity ÷ used margin × 100. In the scenario above it starts at 7,492% and is 7,418% if the stop is hit. If it falls below your broker's stop-out threshold, the broker closes positions automatically, so check that threshold for your account.
Why can margin for UK100 differ between brokers?
Brokers set their own leverage, contract size and margin rules, and regulators cap leverage differently by region and client type. The reference here is 0.5% on a contract size of 1, so replace both with your broker's values before trading.