Lots, Contract Size, Tick Size and Position Sizing

The number entered in a platform's volume field is only the start of position sizing. To understand the exposure, you also need the product's contract size, price increment, tick value, currency and margin rules.

This is why 0.01 lots can represent very different market exposure across two instruments. The label is the same; the contract behind it is not.

A lot is a standardised platform unit. Contract size tells you how many units of the underlying reference are represented by one lot for that symbol. The broker sets this in the symbol specification.

For one instrument, a lot may refer to a defined currency amount. For another, it may represent ounces, barrels, index units or another contract quantity. Never transfer a lot assumption from one product to another.

Minimum, maximum and volume step

The minimum volume is the smallest accepted trade quantity. The maximum volume limits one deal, while a volume limit can restrict total exposure in one direction. Volume step defines the increments that can be entered between the minimum and maximum.

If a symbol accepts 0.01-lot steps, 0.015 may still be invalid. Check the exact specification before calculating an order.

Tick size is the minimum permitted price change for the symbol. A point is usually tied to the platform's quoted decimal precision. A pip is a market convention used mainly in forex and may span one or more displayed points.

These terms are related but not interchangeable. Use the platform specification and the instrument's market convention rather than assuming every final decimal is a pip.

Tick value connects price to money

Tick value expresses how much one tick of price movement is worth for a stated quantity, often one lot. The amount may be shown in the profit currency and then converted into the account currency.

For a simple linear contract, exposure to a price move depends on quantity, contract size and the size of the move. Product-specific calculation methods can differ, so the platform's tick value and profit-calculation method should be checked.

Economic exposure is the value affected by market movement. A simple notional estimate can be written as:

Position quantity × contract size × relevant market price

The relevant formula depends on the product. For some forex calculations, exposure is naturally expressed in the base currency. For a CFD on another asset, price is usually part of the notional value.

Notional exposure is not the amount paid upfront. It is the market value against which gains and losses can develop.

The product can be quoted in one currency, calculate profit in another and reserve margin in a third. The platform then converts the result into the account currency. Tick value can therefore change when a conversion rate changes, even if the contract specification itself is unchanged.

Check both tick value for profit and tick value for loss where the platform provides separate fields. Small differences can arise from the bid and ask used in conversion.

Suppose a plan allows an account loss of 100 currency units and the intended stop is 50 price increments away. The position can use no more than two account-currency units per increment before costs: 100 divided by 50.

The next step is to convert that permitted value into lots using the symbol tick value. If one lot moves by ten account-currency units per increment, the calculated quantity is 0.20 lots. If the accepted step is 0.10 lots, 0.20 is valid; if the calculation were 0.26, rounding down to 0.20 would preserve the stated limit more reliably than rounding up.

This example is deliberately simple. Commission, spread at entry and exit, financing, slippage and currency conversion reduce the amount available for price movement. A real plan should leave room for them.

Margin is collateral reserved to support a leveraged position. Leverage can reduce the initial margin required, but it does not reduce the position's price sensitivity.

A 1% move in the referenced exposure has the same gross market effect whether the initial margin was large or small. Lower margin relative to exposure means account equity can change more sharply in percentage terms. See our guide to leverage, margin and market exposure.

1. Choose the maximum account amount the scenario can lose before costs and slippage.
2. Define a technically meaningful exit or invalidation level.
3. Measure the distance between entry and that level in ticks, points or pips.
4. Confirm tick value for the intended quantity and account currency.
5. Calculate a quantity that stays within the selected amount.
6. Round down to an accepted volume step.
7. Check margin, stop-distance and total-exposure limits.

An illustrative calculation is:

Position quantity = selected risk amount ÷ (stop distance × value per price increment)

This is a planning relationship, not a guarantee. Gaps and slippage can cause the realised loss to exceed the planned amount.

A long position commonly opens at the ask and is valued or closed at the bid; a short position commonly opens at the bid and closes at the ask. The spread therefore creates an immediate difference between the entry price and the price available to close.

Commission, financing and conversion can add to that difference. A position-size calculation that allocates the entire risk amount to stop distance leaves no room for these costs. Use a conservative buffer and recalculate when the product, account currency or holding period changes.

Recheck after specification changes

Contract size, tick value, margin and volume limits can change under applicable terms. Saved calculators and old examples should be checked against the current platform specification before reuse.

Smaller permitted volume steps can make it easier to align a position with a chosen exposure. They do not make a leveraged product low risk. The contract size and price movement still determine the economic result.

The RockGlobal Cent Account page explains the available smaller-step account route. Use the account comparison guide to review pricing, product scope and margin alongside trade size.