Free tool
Futures position size calculator
How many contracts a stop allows at a given risk per trade, on the full-size contract and its micro or smaller contract (the E-mini, QG, on natural gas), with commissions and slippage counted as part of the risk instead of after it.
$12.50 a tick (0.25 index points)
$500.00 at risk
Commission, exchange fees and expected slippage, in and out.
$500.00 at risk
$400.00 per ES contract before costs
Commission, exchange fees and expected slippage, in and out. $400.00 per ES contract before costs
1 contract of ES
Arithmetic on the numbers entered, not a recommendation of any size. Costs are charged per contract on both sides of the trade.
The arithmetic
Fixed-risk sizing starts from a dollar amount you are willing to lose on one trade and works backwards to the number of contracts. The stop sets the loss per contract; the budget sets how many of those losses you can afford at once.
risk per contract = stop in points × dollars per point + round-trip costs
contracts = risk budget ÷ risk per contract, rounded downOn a $50,000 account risking 1% a trade, the budget is $500. An 8-point stop on ES is $400 a contract, $405 with $5 of costs, so the account can hold 1 ES contract and risks $405. The same stop on MES is $40 a contract, $45 with the same costs, which fits 11 micros and $495 of risk, much closer to the budget.
Round down, always
A size rounded up is a risk budget broken on purpose. If the arithmetic says 1.8 contracts, the account holds one; the unused risk is the price of trading a contract that only comes in whole units. Micros shrink that unused remainder, which is most of what they are for.
Costs belong inside the risk
Costs look small in dollars and large in R. A $5 round trip against a $100 stop is 0.05 R: every trade starts five percent of its risk behind, and an edge has to clear that before it earns anything. Halve the stop and the same $5 becomes 0.10 R. A tighter stop is never free.
This is why the screening engine charges costs in R and quotes them per market. At a 0.8-ATR stop on 30-minute bars a round trip costs 0.012 R on NQ, 0.053 R on ES, 0.053 R on crude oil and 0.084 R on natural gas. The market pages give the figure for all eight markets on the screening menu.
Those figures are the menu’s, at its 0.8-ATR stop on 30-minute bars. A screen written in the Strategy Language pays the same round trip for every contract it enters, and what that is in R depends on the stop you write, or on the ATR of its bars when you write none.
What sizing cannot fix
Constant risk per trade is also the benchmark every cleverer sizing scheme has to beat, and on the research record none has. Adding contracts to a winning position lost to constant size in all 42 schemes tested, because each added contract earns less per unit of risk than the first while moving almost perfectly with it. Averaging into a losing one on a grid did no better, and looked profitable only on paper, where a deferred loss can stay open until the data runs out.
Full-size or micro
Every equity-index E-mini, crude oil and gold has a micro at one tenth of its size; silver’s is one fifth. The micro is a finer step, not a cheaper trade: ten micros carry the exposure of one full-size contract and pay fees ten times over, so past a handful of micros the full-size contract costs less for the same risk. The tick value calculator lists every pair.
Questions
- How many futures contracts should I trade?
- As many as your stop allows at the risk you have decided to take on one trade, rounded down, and no more. The calculator does that arithmetic; the risk per trade is a decision it cannot make for you.
- What percentage of an account do traders risk per trade?
- Commonly somewhere between a half and two percent. The range is convention rather than a rule: what matters is that the figure survives a long losing run, which at 1% a trade means twenty losers cost roughly a fifth of the account.
- Should commissions and slippage be part of the risk?
- Yes. A stop that loses $400 plus $5 of costs loses $405, and sizing on the $400 breaks the budget a little on every trade. Counting costs inside the risk also shows what they are in R, the share of each trade's risk spent before it starts.
- Why does the calculator say zero contracts?
- Because one contract at that stop risks more than the budget. Either the stop is too wide for the account on the full-size contract, or the budget is too small; the micro, one tenth the size on most markets, is usually the answer.
- Does position sizing change a strategy's edge?
- No. Sizing sets how much a trade can lose; it cannot turn a strategy without an edge into one with it. On the research record, adding contracts to winners and averaging into losers both lost to constant size at matched risk in every scheme tested.
Size is the easy half.
A size makes a strategy survivable. Whether it makes money is a different question, and the screener answers it against tick data, after costs, before you risk anything on it.