How do I choose the delta?

A larger delta grows size more slowly and keeps drawdowns smaller in dollars; a smaller delta does the opposite. Relating it to the strategy's worst drawdown per contract makes the choice less arbitrary. Test several values and prefer one whose neighbors give similar results.

Does fixed ratio sizing reduce drawdowns?

It reduces size after losses only when profit falls below a step, so a drawdown that starts right after a size increase is taken at the larger size. It changes the shape of growth, not the edge, and cannot turn a losing strategy into a winning one.

Fixed ratio position sizing

Fixed ratio position sizing, popularized by Ryan Jones in the late 1990s, adds one contract each time the account has gained a fixed amount called the delta multiplied by the current number of contracts. Size therefore grows with profits but more slowly than under fixed fractional sizing as the account gets larger.

Senzoukria · Glossary · Updated September 2026

At a glance

Rule: Go from N to N + 1 contracts after a further profit of N × delta
Profit needed to reach N contracts: delta × N × (N − 1) ÷ 2
Decrease: Symmetric: drop a contract when profit falls back below the level
Main choice: The delta, in dollars

How the rule works

Start with one contract. To trade two, the account must earn delta dollars. To trade three, it must earn a further 2 × delta; to trade four, a further 3 × delta. Each new contract costs as many deltas as the contracts already traded, so the cumulative profit required to reach N contracts is delta × N × (N − 1) ÷ 2. Most descriptions apply the rule symmetrically: when cumulative profit falls back below the level that justified the current size, one contract is removed.

Profit levels with a delta of 1,000 dollars
Contracts	Additional profit needed	Cumulative profit
1	—	0
2	1,000	1,000
3	2,000	3,000
4	3,000	6,000
5	4,000	10,000

Compared with fixed fractional sizing

Fixed fractional sizing ties size to total equity, so a large account adds contracts quickly. Fixed ratio ties it to profits since the start, so the step between contracts widens as size grows.
Early in an account's life, a small delta lets size grow sooner than a conservative fraction would.
Neither method knows the stop distance of the next trade. A contract risks 100 dollars on one setup and 400 on another, so the risk per trade can vary widely at the same contract count.
The delta is arbitrary. A common anchor is a multiple of the worst drawdown per contract observed in testing, but it remains a choice to test like any parameter.

In Senzoukria

The desktop has no automatic position sizing method. Quantity is set on the order ticket, where a risk calculator can size an order from a dollar risk and a stop distance in ticks; the autopilot and the simulated demo account carry maximum contract caps; and the prop firm rules form records the maximum contracts of an account. A fixed ratio schedule would be applied by the trader or written into a strategy's own logic. In the automatic backtest the strategy chooses the quantity of each decision, but the engine does not hand it the running profit, so a profit-based ladder must be reconstructed in the script's own state if it is to be tested.

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Frequently asked questions

How do I choose the delta?: A larger delta grows size more slowly and keeps drawdowns smaller in dollars; a smaller delta does the opposite. Relating it to the strategy's worst drawdown per contract makes the choice less arbitrary. Test several values and prefer one whose neighbors give similar results.
Does fixed ratio sizing reduce drawdowns?: It reduces size after losses only when profit falls below a step, so a drawdown that starts right after a size increase is taken at the larger size. It changes the shape of growth, not the edge, and cannot turn a losing strategy into a winning one.

Keep reading

Strategy researchTest a trading strategy, from observation to challenge rulesDefine an observation, question it with the copilot, write a rule and explore costs, drawdown and fictional challenge limits in an interactive example.Quant · Start hereQuant trading for beginners: from idea to backtestDefine a testable rule, choose suitable data and evaluate later periods after costs.Order flow · HubOrder flow trading: the complete guideThe hub. What order flow is, what it shows — aggression, delta, imbalance, absorption, liquidity — and the tools that read it, each linked to a full guide.