MT4 Lot Size Calculator

The number goes into Volume — and the platform may not accept it

The order window in both MT4 and MT5 asks for Volume, and it wants that figure in lots. That is the whole of the handoff from calculator to platform: one number, one field. The trouble is that the number a calculator produces is continuous and the field is not.

A symbol carries a volume step, and the platform only accepts volumes that land on it. If the step is 0.01 then 0.37 is a size; if the step is 0.1 then 0.37 is not, and what you end up with is 0.3 or nothing, depending on the build and the broker's settings. Either way the position you get is not the position you calculated, and the risk changes with it.

Rounding downwards is the safe direction. It leaves the position smaller than the arithmetic wanted, so the money at risk comes in under the limit rather than over it. Rounding upwards — typing 0.4 because 0.37 looked untidy — puts more money at risk than the plan allowed, and it is the more common mistake because it makes the trade feel like the trade you designed. The tool above rounds down onto the step and then reports the risk at the size you can actually enter, so the difference is visible instead of silent.

The floor at the bottom of the field is the harder limit. If the size the risk allows comes out below the minimum volume, there is no version of this trade that fits the plan: the platform will refuse the size, and the only ways out are a tighter stop, which raises the size the risk allows, or no trade.

One lot is not 100,000 units on every symbol

Forex has a convention that usually saves the question: one standard lot is 100,000 units of the base currency. It is a convention, not a rule, and it is set per symbol in the specification rather than inherited from the asset class. Brokers do set other values. Some symbols use 10,000 behind a lot, some use 1,000, and on exchange-traded instruments a lot is often one contract rather than a number of currency units at all.

The consequence is the one that catches people moving between accounts. A lot size that is correct on one broker's EURUSD is a different trade on another's, because the contract size behind the word lot is not the same. This is why a screenshot of someone's position tells you nothing about their risk, and why the pip value a calculator prints can disagree with the pip value your account produces.

The figure that transfers is money per pip per lot. It is contract size multiplied by pip size, it is what the specification's tick fields give you directly, and once you have it the contract behind it stops mattering. The second tool above computes it and shows how far your symbol sits from the 100,000-unit convention, which is the fastest way to see whether a number copied from somewhere else applies to you.

Points are not pips, and the platform counts in points

This is the conversion that decides whether a stop is accepted. MetaTrader measures distances in points, and a point is the last decimal the price shows — one step smaller than a pip on a five-decimal pair. On EURUSD quoted to five decimals, one pip is ten points. On a pair quoted to four, one pip is one point.

The minimum stop level in the specification is expressed in points as well. So a level quoted as 10 points on a five-decimal pair is one pip, not ten. Reading it as pips makes every stop look ten times further away from the limit than it is, and the failure shows up at the worst moment: the order is placed, the stop is rejected, and the position sits there unprotected while you work out why.

The same ten-to-one gap runs through everything the platform reports back. A distance shown as 200 points is twenty pips, and if you size a trade on the assumption that it is two hundred pips you will be ten times too large. The third tool above converts in both directions and checks the result against the level from your own specification, so the answer is in the unit the platform uses rather than the unit you thought in.

Why the same lot size can be refused on one platform and accepted on another

Volume is not the only thing a platform checks when an order is sent. It also checks whether there is enough margin, and that calculation is built from the symbol's margin settings and from the leverage on the account — neither of which is a property of the trade you designed.

The two platforms do not present those settings identically, and they do not run positions identically either: MT5 supports both hedging and netting as accounting modes, where positions in the same symbol are handled differently depending on which the account uses. What that means in practice is that the same lot size in the same symbol can be accepted on one account and refused for insufficient margin on another, with nothing wrong on either side.

This is why no tool on this page reports a margin figure. Any number printed here would depend on settings this page cannot see. The order ticket is the authority: it shows the margin the position will need before you send it, and that is the number to check the size against.

Check the size on the ticket before you send it

Three checks, in the order the platform gives them to you:

1. The volume field took the number you typed. If it snapped the value, the size changed and so did the risk. Read the field after entering it, not before.
2. The stop and take profit were accepted at the distance you set. A rejection here is a stop level measured in points, and it means the distance was shorter than the symbol allows.
3. The margin the ticket reports is inside what the account has free. This is the check that depends on your leverage and on the broker's settings, and it is the one no calculator can do for you.

Doing these three before pressing the button turns the arithmetic on this page into a position that exists. Skipping them turns it into a position you did not plan.

What this page does not assume

No contract size, no volume step, no minimum or maximum volume, no stop level, no leverage and no margin rate. All six are properties of a symbol on a broker, and all six are fields this page asks you to fill in or deliberately leaves out of the calculation.

No live prices either. Every price on this page is one you typed, and the site has no market feed to offer you instead. That is the same rule the rest of the site runs on, and it is the reason the answers here can be checked against your platform line by line rather than taken on trust.

Frequently asked questions

Where do I enter the lot size in MT4?

In the Volume field of the order window, expressed in lots. Open a new order for the symbol, set the volume, then set the stop and take profit at the distance you planned. Confirm the field kept the number you typed — if the symbol's volume step does not include it, the platform will change it.

Is the MT5 position size calculation different?

The arithmetic is identical: money at risk divided by the stop distance divided by the value of one unit of distance. What differs is the platform around it. MT5 exposes the same specification fields, adds netting as an accounting option alongside hedging, and presents margin settings differently — so the same size can be accepted or refused depending on the account, not on the calculation.

Why did MT4 reject my lot size?

Three usual causes, in order of how often they come up. The volume is not on the symbol's volume step. The volume is below the minimum or above the maximum for that symbol. Or there is not enough free margin for the position, which is a function of your leverage and the broker's margin settings rather than of the size itself.

What is the minimum lot size on MT4?

Whatever the minimal volume field says for the symbol you are trading. 0.01 is common on forex, but it is a per-symbol setting, not a platform constant, and some symbols use 0.1 or 1. Read it from the specification rather than assuming, because it is the floor that decides whether a correctly sized trade can be placed at all.

Why is my stop being rejected?

Because it is closer to the price than the symbol's minimum stop level allows, and that level is measured in points. On a five-decimal pair a level of 10 points is one pip, so a stop that looks comfortably far away in pips can still be inside it. Convert the distance into points — the third tool above does it — and compare against the level in your specification.

How many points is a pip in MT5?

Ten on a symbol quoted to five decimals or to three, and one on a symbol quoted to four or to two. It follows from the number of decimals the price shows: a point is the last decimal, and a pip sits one digit further left on the quoting convention for that pair.

Does the contract size change my position size?

It changes what the position size means. Two symbols that both accept 1.00 lot can be trades of completely different magnitude if their contract sizes differ. Work from money per pip per lot, which folds the contract size in, and the number you compute becomes comparable across symbols and across brokers.

Size a currency-pair position from a stop in pips on the lot size calculator, or get the pip value itself from the pip calculator. The risk reward calculator takes the ratio on its own. The same contract-size problem on instruments with no standard contract is handled by the US30 pip calculator for indices and the BTCUSD pip calculator for crypto.