Best Position Size Calculator in 2026 (What Reddit Recommends)

Reddit's trading communities are brutally honest about tools. Nobody earns affiliate commissions in a Reddit comment, so recommendations tend to be genuine. Here is what traders across r/Daytrading, r/Forex, r/StockMarket, and r/Options actually use for position sizing.

What Reddit Actually Says

Across hundreds of position sizing threads, a clear consensus emerges:

• "Use any calculator that does the math." The formula is universal. Account x Risk% / Stop Distance = Position Size. Whether you use a website, a spreadsheet, or a phone app, the answer is the same
• "The best calculator is the one you actually use." Traders who calculate position size before every trade outperform those who wing it — regardless of which tool they use
• "Free is fine." Paid position sizing apps rarely offer meaningful advantages over free calculators for the core function. The math is not complex enough to justify a subscription
• "Build your own in Excel." Many experienced traders prefer a simple spreadsheet formula: =AccountSize*RiskPct/(Entry-StopLoss). No app needed

What Traders Want in a Position Size Calculator

Feature	Reddit Priority	Why It Matters
Account size input	Essential	Base of all calculations
Risk % input	Essential	Defines dollar risk per trade
Entry + stop loss inputs	Essential	Determines risk per share/unit
No signup required	High	Traders do not want accounts for a calculator
Works on mobile	High	Many traders calculate sizing on their phone
No ads covering inputs	High	Ads that block the calculator are deal-breakers
Forex lot size output	Medium	Forex traders need lots, not just units
Commission calculation	Low	Most brokers are commission-free now
Trade journaling	Low	Useful but separate from position sizing

Common Reddit Position Sizing Advice

The same principles appear in every risk management thread, regardless of the subreddit:

1. Risk 1% or less. This is the single most repeated piece of advice in every trading subreddit. Some threads say 0.5% for beginners. Almost nobody serious recommends more than 2%
2. Calculate BEFORE entering. Not during, not after, not "roughly in your head." Before. Every time. No exceptions
3. Stop loss first, then position size. Choose your stop level based on the chart. Then calculate how many shares you can buy at that stop distance. Never choose a position size first and then try to fit a stop loss around it
4. Consistent risk = consistent results. Risking 0.5% on one trade and 3% on the next creates inconsistent outcomes. The trade you risked 3% on might be the loser. Keep risk constant
5. Daily loss limits are non-negotiable. Day traders on Reddit almost universally recommend a 2-3% daily loss cap. Hit your limit, close the platform, come back tomorrow

Free vs Paid Calculators

	Free Browser Calculators	Paid Apps/Software
Core position sizing	✓ Same formula	✓ Same formula
Speed	✓ Instant, no download	~Requires install or login
Cost	✓ $0	$5-$30/month
Trade journaling	✗ Not included	✓ Often included
Broker integration	✗ Manual entry	✓ Some auto-pull account data
Mobile	✓ Browser works on any device	~App required
Privacy	✓ No data stored	~Account + data stored on their servers

For the core function — calculating how many shares to buy — free and paid give the same answer. Paid tools add convenience features for traders who want everything in one place.

Try the Calculator Reddit Principles Built

• Position Size Calculator — free, no signup, no ads over the inputs
• Stock Profit Calculator — see P&L before entering
• Risk/Reward Calculator — evaluate setups