Fixed Fractional vs Fixed Dollar Position Sizing: Which Model Survives a Funded Account in 2026

Two traders open the same simulated $50,000 account on the same morning. Both decide to risk $500 on their first trade. One is using fixed fractional position sizing, which recalculates risk as a percentage of the current balance before every entry. The other is using fixed dollar sizing, which writes the same ticket every time. For the first few trades their accounts look identical. Fifty trades later they do not.

This is one of those choices that feels like a detail and behaves like a policy. It decides how fast an account bleeds during a bad stretch, how fast it recovers afterward, and whether a rule breach comes from a genuinely bad trade or from a sizing model that never adjusted to reality.

In this guide we will define both models precisely, run the arithmetic side by side, and work through which one actually fits inside a funded account with a daily loss limit, a drawdown threshold and a consistency requirement. The conclusion is not that one model wins everywhere. It is that they fail in different places, and you should know which failure you are signing up for.

What fixed fractional position sizing actually does

Fixed fractional position sizing sets risk as a fixed percentage of the current account balance and recalculates it before every trade. If the rule is one percent and the balance is $50,000, the trade risks $500. If the balance falls to $47,000, the next trade risks $470. The percentage never changes. The dollar figure changes constantly.

That single property is the whole argument for the model. Risk contracts automatically during a drawdown and expands automatically during a recovery, with no decision required from the trader in the moment when their judgment is least reliable.

The formula, in the order you actually use it

Start with the percentage, not the position. Multiply the current balance by your risk percentage to get dollars at risk. Then measure the distance from your entry to your stop in points, ticks or cents. Divide dollars at risk by the per-unit value of that distance, and the result is your position size. Round down, never up.

An example. Balance $50,000, risk one percent, so $500 at risk. You are trading a futures contract where the distance to your stop is 20 ticks and each tick is worth $12.50, so the stop costs $250 per contract. $500 divided by $250 is two contracts. If the balance were $47,000, the risk would be $470, which divided by $250 is 1.88, and you round down to one contract.

That rounding step is where the model gets awkward in practice, and we will come back to it. Our post on how much to risk per trade covers the percentage choice itself in more depth.

Why the model cannot be sized to zero

Mathematically, a fixed percentage of a shrinking balance never reaches zero. Ten consecutive one percent losses leave 90.4 percent of the account, not 90 percent, because each loss is measured against a smaller base. Twenty leave 81.8 percent. This is the same compounding that works for you on the way up, running in reverse and refusing to finish the job.

The honest caveat is that this protection is theoretical in a funded account. Your program has a hard drawdown floor, and reaching it ends the account regardless of how gracefully the arithmetic was decaying. Fixed fractional slows the trip to that floor. It does not remove the floor.

What fixed dollar sizing actually does

Fixed dollar sizing sets a constant dollar amount at risk per trade and leaves it there. Every trade risks $500, whether the balance is $50,000 or $44,000. The position size still varies with stop distance, but the money on the line does not.

This is the model most traders use without naming it, because it is how people naturally think. It has real advantages that percentage advocates tend to skip past.

Where fixed dollar is genuinely better

It is executable. You know your number before the session starts. There is no recalculation at the moment of entry, which is the moment you are least equipped to do arithmetic.

It is auditable. A journal of thirty trades all risking $500 makes it obvious when you broke your own rule. A journal of thirty trades risking between $431 and $522 makes rule breaks easy to hide from yourself.

It fits small accounts better. On a $25,000 account with a one percent rule, the risk budget is $250. If a single futures contract with a reasonable stop costs $220 of risk, fixed fractional gives you one contract or none, and the percentage becomes decorative. A fixed dollar figure chosen to fit the instrument is more honest about what you can actually trade.

The cost, stated plainly

Fixed dollar sizing does not know you are losing. After six $500 losses the balance is $47,000 and the next $500 ticket is 1.06 percent of the account rather than 1.00 percent. After twenty it is $40,000 and the ticket is 1.25 percent. The model quietly increases risk exactly when the evidence says to reduce it.

Compare that to drawdown recovery math, where a 20 percent loss requires a 25 percent gain to get back. Fixed dollar sizing steepens the hill it then asks you to climb.

TradeFundrr · Risk Model Comparison

Six losses in a row, two sizing models, two very different accounts

Both traders start at $50,000 and risk $500 on trade one. One recalculates risk from the balance every trade. The other keeps writing the same ticket.

Dollars risked on each successive losing trade

Fixed fractional

1% of current balance, recalculated every trade

Trade 1

$500

Trade 2

$495

Trade 3

$490

Trade 4

$485

Trade 5

$480

Trade 6

$475

Risk shrinks as the balance shrinks. The account cannot be sized to zero by a losing streak alone.

Fixed dollar

$500 per trade, unchanged

Trade 1

$500

Trade 2

$500

Trade 3

$500

Trade 4

$500

Trade 5

$500

Trade 6

$500

Risk stays constant, so it becomes a larger share of a smaller account with every loss.

Where the two models end up after the streak

$47,073

Fixed fractional balance after six straight losses

$47,000

Fixed dollar balance after the same six losses

1.06%

What the next $500 ticket now represents under fixed dollar

The gap after six trades is small. The gap after sixty is not, because fixed fractional compounds in both directions while fixed dollar only compounds the account, never the ticket.

tradefundrr.com

Illustrative example. Figures are hypothetical and used to show the arithmetic of two sizing models, not a projection of results. TradeFundrr provides a simulated trading environment.

The two models compared on the same account

The clearest way to see the difference is to hold everything else constant. Same $50,000 starting balance, same one percent or $500 starting risk, same sequence of outcomes. The table below sets out where each model helps and where it hurts.

Comparison of the two sizing models on identical starting conditions. Behavior described is arithmetic, not a performance claim.

Drawdown behavior is where they separate

Run the same eight loss sequence through both. Fixed fractional at one percent leaves $46,146 after eight consecutive losses. Fixed dollar at $500 leaves $46,000. A difference of $146 on a $50,000 account sounds trivial, and over eight trades it is. The point is not the size of the gap. It is the direction of travel: one model is de-risking without being told, the other is not.

Extend the streak and the divergence widens, because the fixed fractional ticket keeps falling while the fixed dollar ticket keeps taking the same bite out of a smaller pie. This is the same dynamic covered in risk of ruin, where the probability of hitting a floor is driven as much by sizing policy as by win rate.

Recovery is where fixed dollar wins back ground

Honesty cuts both ways. After a drawdown, fixed fractional is trading a smaller ticket, so each winning trade returns less. A trader who cut to $470 per trade needs more winners to climb back than a trader still risking $500. The protection you bought on the way down costs you speed on the way up. There is no version of this where you get both.

Which one you prefer depends on whether your account has a hard floor that ends the game. In a personal account with no external rules, the recovery speed argument carries weight. In a funded account with a drawdown threshold, survival matters more than speed, because a closed account has a recovery rate of zero.

Which model survives a funded account rule set

A funded account changes the question. You are not optimizing a growth curve in isolation. You are trading inside a rule set with three constraints that interact with sizing: a daily loss limit, a maximum drawdown, and often a consistency requirement that caps how much of your profit target can come from one session.

The trailing drawdown problem

A trailing drawdown moves up with your high water mark. Make $2,000 and the floor rises with you, which means your effective buffer stays roughly constant instead of growing. Fixed fractional sizing behaves the same way: it scales with the balance in both directions. The two mechanics are at least pointed in the same direction, which is more than can be said for a constant ticket measured against a moving floor. Our explainer on how trailing drawdown works covers the mechanic itself.

Daily loss limits argue for a hybrid

Here is the practical answer most experienced funded traders land on, and it is neither model in pure form. Use a fixed dollar figure inside the session, chosen so that your maximum number of losing trades stays inside the daily loss limit. Recalculate that figure as a percentage of the balance between sessions, not between trades.

So on a $50,000 account with a $1,000 daily loss limit and a one percent risk rule, you set the session ticket at $500, accept that two full losses ends your day, and revisit the $500 figure at the start of the next session against the new balance. You get the discipline of a constant number intraday and the de-risking of a percentage over time. Our post on risk per trade versus risk per day works through the interaction.

Whatever model you choose, the underlying principle is one the CFTC's own customer education materials make: develop a trading plan targeted to your particular situation and risk tolerance, because having a plan takes some of the emotion out of trading (CFTC Customer Advisory). A sizing model is the part of the plan that survives contact with a bad morning. It is also worth reading the industry risk disclosure that accompanies futures and options accounts, which states plainly that you may sustain a total loss of funds (FIA Uniform Risk Disclosure).

The mistakes that break both models

Neither model fails on its own. Traders break them, usually in the same five ways.

Changing the model mid drawdown

The most expensive mistake in this whole subject. A trader on fixed fractional cuts to $470, gets impatient with the slower recovery, and switches to a fixed $700 ticket to make it back faster. They have now adopted the worst properties of both models at the worst possible moment.

Sizing off equity instead of the drawdown buffer

In a funded account, the number that matters is not your balance. It is the distance between your balance and your drawdown floor. A $50,000 account with $2,000 of remaining buffer is a $2,000 account for sizing purposes, no matter what the equity line says.

Rounding up

Fixed fractional produces fractional answers constantly. 1.8 contracts becomes two, which is an eleven percent overshoot on that trade. Do it for a month and your one percent rule is a 1.1 percent rule. Always round down.

Ignoring stop distance

Both models size from the distance to the stop. A trader who widens the stop without reducing the position has abandoned the model entirely, whatever they still call it. The dollar risk is the input, not the output.

Forgetting that correlated positions are one position

Two contracts in two closely related instruments are not two independent one percent risks. Sized separately they can produce a two percent loss on a single market move. Our post on correlation risk covers how this quietly doubles exposure.

Frequently asked questions

What is fixed fractional position sizing?

Fixed fractional position sizing risks a set percentage of the current account balance on every trade, recalculated before each entry. If the rule is one percent, a $50,000 balance risks $500 and a $45,000 balance risks $450, so exposure falls automatically during a drawdown.

What is the difference between fixed fractional and fixed dollar sizing?

Fixed fractional ties risk to the current balance, so the dollar amount changes on every trade. Fixed dollar keeps the same amount at risk regardless of balance. The first de-risks automatically in a drawdown, the second holds size and recovers faster.

Which position sizing model is better for a funded account?

Neither in pure form. Most funded traders use a fixed dollar ticket within a session so the daily loss limit is easy to respect, then recalculate that ticket as a percentage of the balance between sessions. That keeps intraday discipline while still de-risking over time.

How do I calculate position size with fixed fractional sizing?

Multiply the current balance by your risk percentage to get dollars at risk, then divide that by the dollar cost of your stop distance per unit. Round the result down to a whole number of shares, contracts or lots. Never round up.

Does fixed fractional sizing work with a trailing drawdown?

It fits better than a constant ticket because both the drawdown floor and the position size move with your balance. It does not eliminate the risk, since a trailing drawdown still sets a hard floor that ends the account when reached. Size against your remaining buffer rather than your total balance.

What percentage should I risk per trade in a TradeFundrr account?

That depends on your program's daily loss limit, drawdown and maximum risk per position, which are published for each account and can change. A common starting point is a ticket small enough that three consecutive losses stay inside the daily loss limit. Confirm the figures in the written rules of your own account.

Why does fixed fractional sizing slow down recovery?

Because it cuts position size during the drawdown, so each winning trade returns fewer dollars than it would have before the losses. That slower recovery is the direct cost of the protection it provides. You cannot have automatic de-risking and full-speed recovery from the same model.

Can I use fixed fractional sizing on a small futures account?

Often not cleanly, because of rounding. If one percent of a $25,000 account is $250 and a single contract with a reasonable stop risks $220, the model only ever returns one contract or zero. At that size a fixed dollar figure chosen to fit the instrument is usually more honest.