How to Calculate Lot Size for UK100 (FTSE 100): Contracts, Margin and Position Sizing
BY TIOmarkets
|March 24, 2026Trading UK100 (FTSE 100) CFDs involves understanding how lot sizes, contract values, and margin requirements interact before you place a trade. Because index CFDs are measured in contracts rather than currency units, the position sizing process works differently from forex.
This article explains how UK100 lot sizes work at TIOmarkets, how to calculate point value and required margin, and how to size positions in line with your risk management approach.
What Is a Lot in UK100 Trading?
In forex trading, a standard lot represents 100,000 units of the base currency. Index CFDs work differently. For UK100 at TIOmarkets, one standard lot equals 10 contracts. The minimum trade size is 0.1 contracts, which corresponds to a lot size of 0.01. This means you can scale positions in increments of 0.1 contracts, giving you meaningful flexibility when managing position size relative to your account balance.
The lot size you choose determines both the point value of your trade and the margin required to open and hold the position.
UK100 Contract Specifications at TIOmarkets
The key specifications for UK100 at TIOmarkets are as follows. The standard lot size is 10 contracts, with a minimum lot size of 0.01 (equivalent to 0.1 contracts). The margin requirement is 1%, meaning you need 1% of the full notional value of the position as margin to open the trade. Spreads are variable and typically higher than minimum figures shown. Overnight swap rates should be checked inside the trading platform. Trading hours run Monday to Friday, 01:05 to 23:00 server time, with the market closed on Saturdays and Sundays.
Both MT4 and MT5 are available for trading UK100 at TIOmarkets.
Understanding Point Value for UK100
When trading UK100, price moves are measured in points. One point is a move of 1.00 in the index price. Because UK100 is a GBP-denominated index, the point value is expressed in British pounds.
For one standard lot (10 contracts), a one-point move in the UK100 price produces a profit or loss of £10. For a half lot (0.5 lots, or 5 contracts), a one-point move produces £5. For the minimum lot size of 0.01 (0.1 contracts), a one-point move produces £0.10.
The general formula is:
Point value = lot size × 10 × £1
Because the point value is denominated in GBP, traders holding accounts in other base currencies should note that their profit and loss will be converted to their account currency at the prevailing exchange rate. The TIOmarkets profit calculator handles this conversion automatically, which makes it a practical tool when estimating trade outcomes across different account currencies.
How to Calculate Required Margin for UK100
The margin required to open a UK100 position is calculated as a percentage of the full notional value of the trade. At TIOmarkets, the margin requirement for UK100 is 1%.
The formula is:
Required margin = lot size × contract size × index price × margin rate
Working through a practical example: suppose the UK100 is trading at 8,200 and you want to open a position of 1 standard lot (10 contracts).
Notional value = 10 contracts × 8,200 = 82,000
Required margin = 82,000 × 1% = £820
Because the UK100 is GBP-denominated, this margin figure is in British pounds. If your account is held in a different base currency, the required margin will be converted at the prevailing exchange rate when the position is opened.
For a smaller position of 0.1 lots (1 contract) at the same price:
Notional value = 1 contract × 8,200 = 8,200
Required margin = 8,200 × 1% = £82
As the index price changes, the notional value of your position changes with it, which in turn affects the margin calculation. Always use a current price when estimating required margin rather than a historical reference figure. The TIOmarkets margin calculator allows you to enter your lot size, instrument, and account type to produce an up-to-date margin estimate.
Position Sizing for UK100
Position sizing is the process of determining how many lots to trade based on the amount of capital you are prepared to risk on a given trade. A common approach is to decide the maximum monetary amount you are willing to lose if the trade moves against you to your stop loss level, then work backwards to find the appropriate lot size.
The formula is:
Lot size = risk amount ÷ (stop loss in points × point value per lot)
Working through an example: suppose you have decided you are willing to risk £200 on a trade, and you plan to place a stop loss 50 points away from your entry. The point value for one standard lot of UK100 is £10.
Lot size = £200 ÷ (50 × £10) = £200 ÷ £500 = 0.4 lots
At 0.4 lots (4 contracts), a 50-point adverse move would produce a loss of approximately £200, in line with your risk parameter. You would then check that the margin required for 0.4 lots is within the available margin in your account before placing the trade.
If the same calculation produces a lot size that requires more margin than is available, reduce the lot size accordingly. Preserving sufficient free margin is an important part of managing open positions, as a margin call is triggered at 100% margin level at TIOmarkets, with stop out occurring at 30%, subject to change depending on market conditions and applicable regulatory requirements.
Using the TIOmarkets Calculators
Working through margin and point value calculations manually is useful for understanding the mechanics, but for day-to-day trading it is more practical to use the tools available directly on the TIOmarkets website.
The margin calculator allows you to select your instrument, account type, leverage, and lot size to calculate the exact margin required. This is particularly useful for UK100 because it accounts for the current index price and any applicable currency conversion.
The profit calculator allows you to estimate the monetary outcome of a trade based on your entry price, exit price, lot size, and account currency. For GBP-denominated instruments like UK100, this tool removes the need to manually apply an exchange rate conversion.
Both calculators are available at tiomarkets.com and can be used before placing any trade.
Leverage and Margin on UK100
UK100 at TIOmarkets carries a 1% margin requirement, which corresponds to leverage of up to 1:100. This means that for every £100 of notional position value, £1 of margin is required. While this allows you to take on a larger notional position relative to your account balance, it also means that adverse price moves can produce losses that accumulate quickly. Leverage should be used with a clear understanding of the risk involved.
Leverage is subject to change depending on market conditions and applicable regulatory requirements.
Overnight Financing on UK100
Holding a UK100 CFD position overnight involves an overnight financing charge. For index CFDs, this financing is generally calculated on a different basis from the triple swap applied to forex positions. The applicable rates and the exact calculation method for UK100 should be checked inside the trading platform, as these can vary. There is no confirmed fixed rollover time applicable to UK100 — check in-platform for current rates before holding positions overnight.
Trading UK100 at TIOmarkets
UK100 is available to trade on both MT4 and MT5, across Standard, Raw, and VIP Black accounts. Hedging is permitted on all account types. Traders seeking a swap-free arrangement should contact TIOmarkets directly to enquire about Islamic account eligibility and applicable conditions.
FAQ
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TIOmarkets offers an exclusively execution-only service. The views expressed are for information purposes only. None of the content provided constitutes any form of investment advice. The comments are made available purely for educational and marketing purposes and do NOT constitute advice or investment recommendation (and should not be considered as such) and do not in any way constitute an invitation to acquire any financial instrument or product. TIOmarkets and its affiliates and consultants are not liable for any damages that may be caused by individual comments or statements by TIOmarkets analysis and assumes no liability with respect to the completeness and correctness of the content presented. The investor is solely responsible for the risk of his/her investment decisions. The analyses and comments presented do not include any consideration of your personal investment objectives, financial circumstances, or needs. The content has not been prepared in accordance with any legal requirements for financial analysis and must, therefore, be viewed by the reader as marketing information. TIOmarkets prohibits duplication or publication without explicit approval.
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