Position sizing: turning a risk percentage into a lot size
Your risk percentage becomes a lot size by dividing the money you are willing to lose by the loss that one lot would produce at your stop.
- Money at risk you set
- —
- Actual loss at stop
- —
- Pip value at this size
- —
Ignores spread, commission and slippage. During fast markets, it is possible for a stop to fill at a worse price than specified.
Worked example
USD/ZAR 16.32 · pulled 2026-09-28| Step | What | Calculation | Amount |
|---|---|---|---|
| 1 | Money at risk | 33 000.00 × 1% | R 330.00 |
| 2 | Pip value, 1 standard lot | USD 10.00 × 16.32 | R 163.20 |
| 3 | Risk per pip | 330.00 ÷ 25 pips | R 13.20 |
| 4 | Exact position size | 13.20 ÷ 163.20 | 0.0809 lots |
| 5 | Rounded down to 0.01 lot | floor(0.0809, 0.01) | 0.08 lots |
| 6 | Actual loss if the stop is hit | 0.08 × 163.20 × 25 | R 326.40 |
The three inputs that decide every position size
Your risk percentage becomes a lot size by dividing the money you are willing to lose by the loss that one lot would produce at your stop. Three inputs drive that division: the account balance you are risking, the percentage you have chosen to risk, and the distance in pips between your entry and your stop loss. Change any one and the lot size changes.
The account balance should be the figure you can actually trade, not a target. If you fund by EFT or instant EFT and the money has not cleared, it is not yet risk capital. The percentage is a decision you make before you open the chart, not after.
The stop distance is the part most traders get wrong. A stop placed at a round number because it looks tidy is not a stop based on the chart. The calculator can only size what you give it, so the stop level must come from your analysis first.
| Figure | Source | Checked |
|---|---|---|
| Licensee names and status | FSCA list of authorised financial services providers — fsca.co.za | 2026-09-29 |
| Session windows | Fixed UTC windows; London and New York shift in their DST | On change |
| USD/ZAR | open.er-api.com | 2026-09-28 |
| Funding limits and fees | Set by the provider and the broker — not published here | Changes without notice |
Undated figures are opinions in disguise. What we could not trace back to a source was dropped rather than guessed at.
Why pip value and account currency do the real work
A lot size is only meaningful once you know what one pip is worth in your account currency. Most retail accounts are denominated in ZAR or USD, and the pip value depends on the pair you are trading and the currency the pair is quoted in. That is why a position size calculator needs your account currency as an input, not just the pair.
This is where a pip calculator and a position size calculator overlap. The pip calculator answers what one pip movement is worth for a given lot; the position size calculator works backwards from the risk you have set. Run them together and the arithmetic stays honest.
A forex profit calculator uses the same pip value in the other direction, converting a planned target distance into a potential gain. It is a planning tool, not a forecast. It tells you what the maths would produce if the target were reached, and nothing about whether it will be.
| Figure | Value | Source |
|---|---|---|
| Indicative USD/ZAR | 16.32 | open.er-api.com, pulled 2026-09-28 |
| How often it moves | Every trading day | — |
| The rate your account uses | Your broker's own conversion | The broker's rate card |
| Symbol on this site | R | — |
An indicative rate is for sizing a position in your head, not for settling one. That spread between the market rate and the broker's own is a cost worth counting.
What a South African trader should check before trusting any calculator
A calculator is only as good as the broker inputs behind it. Spreads, swap or financing charges, and any commission change the effective pip value, and those figures differ by broker and by account type. Check them on your broker's funding or contract specifications page rather than assuming a default.
Leverage is the other input that quietly changes risk. A large lot size on a small balance is a leverage decision, and leverage amplifies the loss as readily as the gain. The calculator will show the lot size the risk percentage implies; if that lot size looks impossible for your balance, the risk percentage is too high for the account.
Before funding anything, confirm the firm holds an FSCA ODP licence to offer leveraged FX to South African residents. The FSCA publishes its list of authorised financial services providers at fsca.co.za. Look up the FSP number on that register yourself rather than relying on a logo on a website.
What the FSCA register is
- Regulator
- Financial Sector Conduct Authority (FSCA)
- Register
- FSCA list of authorised financial services providers
- Published at
- fsca.co.za
- Covers retail forex
- Yes — the register has a category for it
- Last read by us
- 2026-09-29
- Entries transcribed here
- 30
A register says whether a firm holds a licence on the day you look, and nothing about how it treats clients. Search by the registered company in the footer rather than the name on the homepage.
Session timing changes the risk you are actually taking
South Africa sits on SAST, UTC+2, which puts the London session at 10:00 to 19:00 local time and New York at 14:00 to 23:00. The London and New York overlap runs from 14:00 to 19:00 SAST, when liquidity is deepest and spreads are typically at their tightest. Sydney opens at 23:00 and Tokyo at 02:00 SAST.
Thin hours matter for position sizing because a wider spread is a real cost on entry and exit. A stop distance that looks reasonable in the overlap can be hit by noise in a quiet session. If you only trade one session, size for the conditions in that session, not for the best spread you have seen.
None of this replaces the calculator. It tells you when the inputs you typed are most likely to behave as expected. Funding by EFT, instant EFT, Ozow, Capitec Pay, card or bank transfer is a separate step, and the cleared amount is what belongs in the balance field.
| Part of the day | Local time · SAST |
|---|---|
| Busiest window | 14:00-19:00 SAST — London and New York open together |
| Thinnest stretch | 23:00-08:00 SAST — Sydney alone, wider spreads |
| European open | 10:00-19:00 SAST |
| US open | 14:00-23:00 SAST |
| Closed | Friday New York close until the Sydney open on Monday |
Hours are shown for the clocks in force today: London is on GMT until 28 March, New York is on EDT until 1 November. South Africa does not change clocks, so each move shifts these local times by an hour and the page is rebuilt on the day it happens.
Rounding a lot size to what the platform will actually accept
A risk percentage rarely divides into a clean lot size. The calculator will return something between the minimum tradeable unit and the next step up, and the platform will only accept one of those. Rounding up quietly increases the risk taken beyond the figure that was intended. Rounding down keeps the loss inside the plan but changes the expected outcome.
The correct order of operations is to decide the risk first, calculate second, and round third, never the reverse. Traders who pick a round lot because it looks tidy and then work backwards are sizing by habit rather than by risk. That reversal is the most common failure mode on this page, and it is invisible in the trade ticket.
Before relying on any figure, check the instrument's minimum volume and volume step in the broker's own contract specifications, published on the broker's site. Those two numbers decide whether the calculated size is even placeable. If the rounded size falls below the minimum, the trade cannot be taken at the intended risk, and the honest answer is to skip it.
| Platform | What it is | Who makes it |
|---|---|---|
| MetaTrader 4 | The older standard; expert advisors and a large script ecosystem | MetaQuotes |
| MetaTrader 5 | The newer build; more order types and timeframes | MetaQuotes |
| cTrader | Depth of market and a different order model | Spotware |
| The broker's own app | Usually simpler, and tied to that one firm | The broker |
A platform is software, not a safeguard: the same terminal is offered by licensed and unlicensed firms alike. App stores list software. Registers list permissions - and that is the one that matters.
Stop distance in pips must come from the chart, not from the risk budget
A position size calculator needs a stop distance, and that distance has to be read off the chart at a level where the trade idea is genuinely wrong. It cannot be chosen because it produces a convenient lot size. When the stop is widened or tightened to make the arithmetic work, the calculator is being used to justify a trade rather than to size one.
This distinction matters because the two inputs are independent. Risk percentage is a decision about the account. Stop distance is a decision about the market. Feeding a market decision into an account decision, or the other way round, produces a number that looks precise and means nothing. The output is only as honest as the stop that was entered.
A practical consequence: if the chart gives a wide stop and the resulting size is very small, that is the calculator doing its job. The trade is simply expensive in risk terms. Reducing the stop to fit a preferred lot size moves the stop inside normal market noise, which is how a planned loss becomes an unplanned one.
The paperwork, and what each piece proves
- Green barcoded ID book or smart ID card, or passport
- Who you are
- Selfie with the ID document
- That the document is in your hands
Brokers usually also ask for proof of address - municipal bill or bank statement; requirements differ per firm. The firm's own sign-up page is the list that counts.
Where the risk percentage itself comes from, and why the calculator cannot check it
Every position sizing tool on this page takes a risk percentage as given. Nothing in the arithmetic questions it. A trader who enters an aggressive figure gets a large lot size returned without warning, and the calculator will look just as authoritative as it did with a conservative one. The tool sizes the trade, it does not vet the plan.
South African traders should treat the risk percentage as a written rule rather than a mood. It belongs in a trading plan alongside the maximum number of open positions and the daily loss limit, because those three interact. Several positions each sized at the same percentage of the same account add up to a much larger exposure than any single calculation shows.
The FSCA's public register at fsca.co.za lists authorised financial services providers, and readers can check there whether a firm offering signals, education or managed positions is authorised to do so. Position sizing advice from an unauthorised source carries no regulatory protection, however sound the arithmetic looks.
| Rail | What it is | Who sets the limit and the fee |
|---|---|---|
| EFT / instant EFT | Bank transfer | Your bank and the broker |
| Ozow | Payment service | The provider and the broker |
| Capitec Pay | Payment service | The provider and the broker |
| Card | Card payment | Your card issuer and the broker |
| Bank transfer | Bank transfer | Your bank and the broker |
Limits and fees are set by the provider and the broker and change without notice, so they are not printed here. Verify it twice, once in the app and once on the funding page, and never withdraw to an account that did not fund you.
Questions we are asked
They are usually the same tool under two names. A lot size calculator takes your risk amount and stop distance and returns a volume in lots. A position size calculator does the same job but starts from a risk percentage of your balance, which is the safer way to think about it.
Yes, if you want to check the output. The pip calculator tells you what one pip is worth for the pair and lot size you are considering, in your account currency. Comparing that figure against the position size the calculator suggests is a quick way to catch a wrong input.
No. It converts a target distance in pips into an amount using the pip value, nothing more. It cannot tell you whether the target will be reached, and it does not include spreads, swaps or commission unless you enter them yourself. Treat it as arithmetic, not as a forecast.