Calculators
Calculators for the sums that come before a trade or a retirement decision. Each prints its working line by line, so you can check the arithmetic and see which input moves the answer most.
Technical Analysis
- Fibonacci Retracement Calculator
Retracement and extension levels from a swing low and high, in an uptrend or a downtrend.
Background: Fibonacci retracement, defined
- Moving Average Calculator
Simple and exponential moving averages from a list of closing prices, with every step shown.
Background: the exponential moving average
Swing Trading
- Position Size Calculator
The share count from your account risk and stop, the reward in R, and the loss if the stock gaps past the stop.
Background: swing trading a small account
Options
- Covered Call Calculator
Premium income, maximum profit, breakeven and the upside given up when you sell a call on shares you own.
Background: covered calls, defined
ETFs
- Leveraged ETF Decay Calculator
How a daily-reset 2x, 3x or inverse fund drifts from its multiple of the index over a run of days.
Background: volatility decay
Dividends
- Dividend Yield Calculator
Current yield, yield on cost and yearly income from a dividend, a share price and your share count.
Background: yield on cost
Prop Trading
- Prop Firm Consistency Calculator
Whether your best day breaks a consistency rule, and the total profit you need for it to pass.
Background: a prop evaluation case study
Retirement
- Social Security Claiming Calculator
Your monthly benefit at each claiming age from 62 to 70, and the age where waiting starts to pay.
Background: full retirement age
- Retirement Withdrawal Calculator
How long savings last at a chosen withdrawal, return and inflation rate, year by year.
Background: the 4% rule
Before you trust an output
Every calculator runs in your browser and sends nothing anywhere. The answers are only as good as the inputs, and the inputs that matter most are the ones you have to estimate: where your stop goes, what a fund's index will do day by day, how long retirement lasts, what return a portfolio earns. A calculator will turn a guess into a number with two decimal places without complaint.
Change one input at a time and watch the output. If a slightly wider stop halves the share count, or one percentage point of return adds a decade to how long savings last, that sensitivity is the useful result, because it tells you which estimate deserves the most checking.