Option Calc 225

【What is Option Calc 225?】
Option Calc 225 calculates the theoretical price of index options on the spot using the Black-Scholes formula. It focuses on Nikkei 225 and Nikkei 225 Mini options, but also works for other index and single-stock options such as Securities Options (kabu options) and TOPIX options. Even beginners can get theoretical prices and Greeks just by entering the required values. No brokerage account or login needed—install and start right away.
【Who it's for】
・Beginner to intermediate users starting options trading
・Those checking whether a quoted or executed price is expensive or cheap vs. the theoretical price
・Those testing how prices and Greeks move when changing strike, days to expiration, or volatility
・Those wanting quick theoretical values for Nikkei 225 and Mini options
【Main Features】
■ Black-Scholes Theoretical Price
Calculates call/put theoretical prices from the underlying price, strike, time to maturity, interest rate, expected dividend yield, and volatility (IV).
■ Greeks Display
Shows Delta, Gamma, Theta, Vega, and Rho at once—sensitivity to price moves, time decay, volatility, and rates at a glance.
■ Auto Contract Month & Last Trading Day
Select an instrument and contract month, and the last trading day (business day before SQ) is calculated automatically, with weekend/holiday adjustments. It can also be set manually.
・Nikkei 225 Options: quarterly months (up to 8 years) and other months (nearest 8)
・Nikkei 225 Mini Options: weekly Friday/Wednesday months (11-month system)
・Others: nearest 12 months
■ Auto-Linked Days to Expiration & Interest Rate
Calculates days to expiration from the planned trading date and last trading day, then auto-selects the rate tenor (1 week, 1/3/6/12 months) by remaining term.
■ Default Value Settings
Pre-register the expected dividend yield and rates for each tenor to skip repeated entry, and update them to current market conditions.
【A Focus on Usability】
・Single-screen layout from input to results, with minimal scrolling
・Large text and easy-to-tap buttons to prevent input errors
・Call (up) and Put (down) distinguished by ▲▼ symbols and text, not color alone
・Light / Dark / device-synced display modes
・Japanese / English / device-synced languages
【Color Universal Design (CUD)】
This app adopts the color scheme from the "Model Color Palette for Color Universal Design Guide Book, 2nd Edition." Since color perception varies, information is conveyed without relying on color alone, using symbols, labels, and contrast so the screen is easy to read for everyone.
【Notes on Use】
・Theoretical prices and Greeks are reference values based on the Black-Scholes model and may differ from actual market prices or values from brokerages and clearing institutions.
・Margin (VaR) calculation, P&L simulation, and real-time price retrieval are not supported.
・Volatility (IV) is entered manually—use the mid-price of best quotes, executed prices, etc.
・Update default values such as rates and dividend yield to the latest figures before use.
・This app is for informational purposes only and does not recommend trading any instrument or method. Final investment decisions are your own responsibility.
【Privacy】
All calculations run on your device. The privacy policy is available in the app's settings screen or on the official website.
From beginner learning to daily price checks, make theoretical option prices more accessible. Try Option Calc 225.