Home / Tools / Position sizer
Bitcoin investment calculator: how much can you put in?
Enter three numbers: your investable money, how much of it you can accept losing, and how far you assume crypto could fall at worst. The position sizer returns a cap for this buy and splits it into batches.
How it's worked out: cap = investable money × the loss you can accept ÷ the worst drop you assume. The cap only holds if the real drop is no deeper than the level you picked; the default is 100%, which treats the whole stake as lost. When the result is above 10%, the calculator also shows the figure capped at 10%, and the batch size uses the capped figure (see the table below for the rule). This tool does arithmetic only; it predicts no returns on any asset and is not investment advice.
All 16 results side by side (for $100,000)
Each of the two dropdowns has four levels, which gives 16 combinations. With $100,000 entered as investable money, the caps are as follows, with the share of the $100,000 in parentheses:
| Acceptable loss \ Assumed drop | 50% | 70% | 90% | 100% |
|---|---|---|---|---|
| 5% | $10,000 (10%) | $7,143 (7.1%) | $5,556 (5.6%) | $5,000 (5%) |
| 10% | $20,000 (20%) | $14,286 (14.3%) | $11,111 (11.1%) | $10,000 (10%) |
| 15% | $30,000 (30%) | $21,429 (21.4%) | $16,667 (16.7%) | $15,000 (15%) |
| 20% | $40,000 (40%) | $28,571 (28.6%) | $22,222 (22.2%) | $20,000 (20%) |
Of the 16 results, 11 are above 10%, 2 are exactly 10% and 3 are below it. This site's rule of thumb for beginners is to start at 1%–3% of investable money, with 10% as the ceiling. That is a rule of thumb from this site and does not come from research. So anything above 10% is capped at 10%, and anything below 10% is used as calculated. When a result is above 10%, the calculator also shows the capped figure next to it.
Why assume a worst drop first
The loss you can accept is measured against all your investable money. The part that goes into crypto can fall much further. In bitcoin's last bear market the daily high was 69,000 USDT (10 November 2021) and the daily low was 15,476 USDT (21 November 2022), a peak-to-trough fall of about 77% (source: Binance public market data API, BTCUSDT monthly and daily candles, UTC).
That fall was deeper than the 70% level, so to cover a market like it you need to pick 90% or 100%. Altcoins can go to zero, so size altcoin money at the 100% level. The shallower the drop you pick, the higher the cap, and if the real drop goes deeper, you lose more than the share you accepted.
How to use the cap once you have it
The cap means "no more than this". If you are unsure, start at 1%–3% and add later. If you add too much and then want to cut back, you have to sit through a drop first.
The number of batches only divides the cap evenly; which day you buy each batch is up to you. For fixed weekly or monthly buys, use the DCA calculator to get the amount per buy and the plan total, and see weekly or monthly buys for choosing a frequency. For which kind of market favors batches and which favors a lump sum, this 10-buy worked example has the month-by-month figures.
What this calculator can't tell you
It does one multiplication and one division. It doesn't know whether your emergency fund is in place or whether the three numbers you entered are honest. It makes no call on which coin to buy or whether now is a good time. And it won't warn you later when prices rise and your share goes over the cap. All three inputs are your own assumptions, and the result is no more reliable than they are.
Risk warning: crypto prices are extremely volatile and you can lose your entire principal. The content on this site is investor education and a roundup of common practices, not investment advice, and is not responsible for any investment outcome. Past performance does not indicate future returns.
AboutDisclosureDisclaimerPrivacyCorrections
© 2026 Dingtouma · Position & Risk Notes · This site holds none of your funds and provides no trading services