Retirement planning, simplified
The only iOS calculator that does marginal tax brackets, capital gains stacking, and Social Security taxation correctly. 17 analysis tools. Zero data collection.
What makes CoastIQ different
No App Store competitor does tax math correctly. CoastIQ does.
Tax-Accurate Projections
Marginal federal brackets, capital gains stacking, Social Security taxation, NIIT, state taxes, FICA, and IRMAA — computed correctly.
Monte Carlo Simulation
1,000+ trial parallel simulation with correlated stock/bond returns and historical backtesting from 1928 to today.
Roth Conversion Optimizer
Bracket-filling strategy that respects ACA subsidies and IRMAA thresholds. Year-by-year conversion plan with incremental tax.
100% On-Device
All computation happens on your iPhone or iPad. No cloud, no accounts, no data collection. Your financial data never leaves your device.
17 analysis tools
From the blog
Tax strategies, FIRE planning guides, and retirement calculator deep-dives.
7 best Monte Carlo retirement calculators (2026)
We tested 7 Monte Carlo retirement calculators on what matters: correlated returns, spending flexibility, and tax modeling inside each simulation path.
Best Retirement Calculators Compared (2026)
Every 'best retirement calculator' list ranks tools by UI. We ranked the top 8 on what actually matters: tax handling, Social Security modeling, scenario complexity, and Monte Carlo methodology.
FIRE number calculator - what the formula misses
Annual expenses × 25 is the napkin formula for your FIRE number. After taxes, time horizon, and healthcare adjustments, the real number runs 25-40% higher.
Plan your retirement with confidence
Free dashboard with success rate, metrics, and projection chart. Upgrade to Pro for all 17 tools, unlimited scenarios, and PDF exports.
Get CoastIQ