How to use the trading compounding calculator
- Enter your starting balance and pick your account currency.
- Enter the return per month as a percentage. Be conservative: the default is an illustration, not a target.
- Enter the number of months, from 1 to 600.
- Add a monthly deposit if you will add money each month, or a negative number for a monthly withdrawal. The deposit lands at the end of each month, after that month's return.
- Optionally enter a target balance. The calculator then shows the monthly return that would be needed to reach it in the time you chose.
You get the end balance, your total contributions, the total profit, the same account without compounding, the extra that compounding adds, the effective annual return and the time to double. A line chart sets compounding against simple growth and the money you paid in, and a column chart shows the balance at the end of each period.
The compounding formula
balance after n months = S × (1 + r)^n + D × ((1 + r)^n − 1) / r
effective annual return = (1 + r)^12 − 1
return needed (no deposits) = (target ÷ S)^(1 ÷ n) − 1
- S is the starting balance and n the number of months.
- r is the return per month as a fraction, so 3% is 0.03.
- D is the deposit added at the end of each month, or the withdrawal if it is negative.
The calculator steps through the months one at a time, which gives the same answer as the formula. "Without compounding" means profits are not reinvested: each month earns the return on the money you paid in, and nothing is earned on earlier profits. The difference between the two is the extra from compounding.
Worked example
An account starts with 10,000 and earns 3% a month for 24 months, with no deposits.
These are the numbers the calculator opens with. Compounding adds 3,127.94 over simple growth in two years, and the gap widens every month because the base it works on keeps growing. To see the target helper, set the target to 20,000: the account must earn 2.93% a month for 24 months to double, which is a 41.42% effective annual return.
Why steady monthly returns are not realistic
A compounding calculator draws a smooth line. Trading does not produce one. Please read these figures as arithmetic, not as a plan, and not as something to expect.
A steady 3% a month is about 42.58% a year. Sustaining anything near that for two years, with no losing months, is far beyond what most traders achieve, and the longer the period, the bigger the gap between the line and reality. Real returns are uneven: some months are strong, some are negative, and some are flat. The calculator uses a constant rate only because it makes the maths clear.
Unevenness also costs money. Equal percentage gains and losses do not cancel: a month of +50% followed by a month of −50% leaves you at 75% of where you started, not at 100%. The more your returns swing, the further your real growth falls below the growth of the same average return delivered steadily.
Drawdowns interrupt compounding most of all. Here is a short example with the same account. After 12 months at 3% the balance is 14,257.61. Now suppose one bad stretch takes 30% off it: the balance becomes 9,980.33, which is below the 10,000 you started with. To get back to 14,257.61 it needs a gain of 42.86%, and at 3% a month that takes 12.07 months, a whole second year. If the next 12 months then earn 3% each, the account ends month 24 at 14,229.56, not 20,327.94. One 30% drawdown costs 30% of the final balance, however well everything else goes. The drawdown recovery calculator shows the same arithmetic for any fall.
Nothing on this page is a promise or a forecast. Past results do not guarantee future ones, and no return can be assumed.
How deposits and withdrawals change the result
Regular deposits matter more than the return in the early years. With a small account the money you add each month is larger than the profit it earns, so the balance grows mainly through contributions. Compounding takes over later, when the balance is large enough for the monthly return to outweigh the deposit.
Take the same account with a 500 deposit each month. After 24 months at 3% it holds 37,541.18, of which 22,000 was paid in and 15,541.18 is profit. Without compounding, the same inputs end at 33,340.00, so compounding adds 4,201.18.
Withdrawals work the other way. A fixed withdrawal takes money out before it can earn, and if it is larger than the monthly gain the balance runs down. The calculator stops the balance at zero and tells you the month it runs out, so you can see how long a given withdrawal lasts at a given return.
Compounding versus simple growth
Simple growth earns the return on the money you paid in and leaves the profits alone. Compounding reinvests them, so profits earn their own return. The two lines start together and then separate, and the separation accelerates.
In trading, compounding is the idea behind sizing positions as a percentage of the current balance: risk 1% of 10,000 today, 1% of 12,000 after a good run, 1% of 8,000 after a bad one. The size grows with the account and shrinks with it, which is a protection as well as an engine. Fixed-size trading is closer to the simple line. Which suits you depends on how stable your results are, and the expectancy calculator is a good place to check that first.
Common compounding mistakes
- Treating a steady return as realistic. A constant 3% or 5% a month is a teaching tool, not a plan.
- Confusing monthly and yearly returns. 3% a month is not 36% a year. Compounded it is 42.58%, and it is still not likely.
- Ignoring drawdowns. A single large loss resets years of compounding. Model the downside as well as the upside.
- Forgetting costs and taxes. Commissions, spreads, slippage, platform fees and taxes reduce the return you can compound.
- Using the best months as the average. Your average return includes the losing months.
- Using a withdrawal that outruns the return. If you take out more than the account earns, the balance shrinks.
What the calculator does not know
The calculator uses one constant return for every month, adds deposits at the end of each month, and ignores fees, taxes, slippage, inflation and the order in which gains and losses arrive. Real returns are uneven, and a bad sequence early on can matter far more than the average suggests. The effective annual return is the arithmetic of the monthly rate, not an estimate of what you will earn. The required-return helper finds the rate that exactly reaches a target and does not judge whether that rate is possible. Nothing here is investment advice.
Frequently asked questions
How do you calculate compounding returns on a trading account?
Multiply the balance by one plus the monthly return, once for each month. For 10,000 at 3% a month for 24 months, that is 10,000 × 1.03^24 = 20,327.94. Deposits are added after each month's return.
What is the compounding formula?
Balance = S × (1 + r)^n + D × ((1 + r)^n − 1) ÷ r. S is the starting balance, r the monthly return, n the number of months and D the monthly deposit. With no deposits, the second part is zero.
How do I convert a monthly return to an annual return?
Compound it: (1 + monthly return)^12 − 1. A 3% monthly return is 1.03^12 − 1 = 42.58% a year. It is higher than 3% × 12 = 36% because each month earns on the earlier gains.
What monthly return do I need to double my account?
For a given time, the return is 2^(1 ÷ months) − 1. Doubling in 24 months needs about 2.93% a month. Doubling in 12 months needs about 5.95% a month, which very few traders sustain.
Is compounding realistic in trading?
The arithmetic is exact, but the steady returns it assumes are not realistic. Real returns are uneven, losing months and drawdowns interrupt compounding, and costs reduce the rate. Use the calculator to understand how growth works, not to predict your own results.
How long does it take to double an account?
The time to double is ln 2 ÷ ln(1 + monthly return). At 3% a month it is 23.45 months, close to the "rule of 72" estimate of 72 ÷ 3 = 24. At 1% a month it takes about 70 months.
How do deposits affect compounding?
Deposits add to the base that earns the return, and in the early years they usually matter more than the return itself. With a 500 monthly deposit the example above ends at 37,541.18 instead of 20,327.94, with 22,000 of it paid in.
Do drawdowns break compounding?
They interrupt it. After a 30% drawdown the balance is 70% of the peak, and recovering it needs a 42.86% gain, so the final balance ends up 30% lower than the smooth path. Compounding rewards staying in the game with a balance intact.
Should I risk a percentage of my balance or a fixed amount?
A percentage compounds: the amount grows as the account grows and shrinks as it falls, which is a built-in brake. A fixed amount grows the account in a straighter line. Many traders use a small percentage per trade. See the risk of ruin calculator for what each size means for your chances of a deep drawdown.