Moving a strategy between brokers is a measurement problem before it's a trading one. The goal isn't to copy the lot size — it's to reproduce the same money at risk. This is the step-by-step workflow to compare a strategy's risk on two accounts and land on the size that keeps them equal.
Fix the reference first
Pick the account the strategy was validated on — the one whose backtest or track record you trust — and call it Broker A. Everything you compute for Broker B is relative to it. Nail down two facts about the position on A: the lot size it trades, and the pip value per lot for that symbol in your account currency. Those are the reference you'll hold constant.
Read both contract specs
Before any arithmetic, pull the pip value per lot from each broker's contract specification — don't assume they match just because the symbol name does. The value can differ because of contract size, tick definition, digits, or an account-currency conversion. Write down, for the same symbol and account currency:
- Pip value per 1.00 lot on Broker A.
- Pip value per 1.00 lot on Broker B.
- The stop distance in pips the strategy uses (this stays the same — it's a chart decision, not a broker one).
Convert to money, then equalize
Turn lots into money on the reference account, then solve for the size on B that reproduces it. Risk on A is lot size × pip value × stop pips. To keep the same money at risk, scale the lots by the ratio of pip values:
lotsB = lotsA × (pip valueA ÷ pip valueB)
The direction is counter-intuitive: if Broker B pays more per pip, you need fewer lots there, not more.
A worked comparison
A breakout strategy trades 0.50 lots of gold with a 30-pip stop on Broker A, where the pip value is 10 per lot. Risk on A is 0.50 × 10 × 30 = 150. Broker B lists the same symbol at 12 per lot. The equivalent size is 0.50 × (10 ÷ 12) = 0.42 lots. Check it: 0.42 × 12 × 30 = 151 — the small rounding aside, the money at risk matches. Blindly copying 0.50 lots to Broker B would have risked 0.50 × 12 × 30 = 180, a 20% overshoot on every trade.
Same strategy, same stop, matched risk: 0.50 lots on A ≈ 0.42 lots on B.
Gotchas when you run the same EA on both
Comparing risk is easy to get wrong when an EA sizes positions automatically. Watch for:
- Hard-coded lots — a fixed lot input carries the risk difference straight through; the EA won't warn you.
- Percent-risk sizing that reads the wrong pip value — if the EA derives pip value from a spec that doesn't match the live symbol, its "1% risk" isn't 1%.
- Different digits or fractional pips — a stop expressed in points can mean a different distance on each feed.
- Rounding to the lot step — Broker B may only allow 0.01 increments, so the matched size gets rounded; check the residual risk after rounding.
- Non-USD symbols — the pip value on either side may drift with the exchange rate, so a match taken at one moment won't hold indefinitely.
The comparison checklist
- Same symbol, same account currency, same stop distance on both sides.
- Pip value per lot read from each broker's contract spec, not assumed.
- Reference risk (money) computed on Broker A.
- Equivalent lots on B from the ratio, then verified back into money.
- Rounded to B's lot step, with the residual risk difference checked.
Run the numbers
The Lot Equivalence tool below is this workflow in one screen: enter the Broker A lot size, the stop in pips, and the pip value per lot on each broker. It returns the equivalent lots on Broker B, the money at risk at your stop, the pip-value ratio, and the risk-per-pip on both sides — so you can confirm the two accounts carry the same exposure before you switch the strategy over.
Takeaway
Comparing risk between brokers is a three-line calculation: read both pip values, convert your reference lots to money, and solve for the size that reproduces that money on the other side. Do it for every symbol and every account change — the lot number that was correct on one broker is just a coincidence on the next.
