CoastIQ is a retirement planning calculator built for the FIRE community. Unlike every other calculator that uses flat tax estimates, CoastIQ models your actual taxes — marginal federal brackets, capital gains stacking, Social Security taxation, NIIT, FICA, IRMAA, and state-level taxes. Features Monte Carlo simulation with 1,000+ parallel trials, Roth conversion optimizer, historical backtesting since 1871, and 17 analysis tools. 100% on-device — no cloud, no accounts, no data collection.

Hey Product Hunt! I built CoastIQ because every retirement calculator I tried used flat tax estimates — and the numbers were always wrong. As someone pursuing FIRE, I needed projections I could actually trust. CoastIQ models your real tax situation: marginal federal brackets, capital gains stacking on top of ordinary income, Social Security taxation thresholds, NIIT, IRMAA, and state taxes. It runs 1,000+ Monte Carlo trials with correlated returns, backtests against every retirement year since 1871, and includes a Roth conversion optimizer that respects ACA and IRMAA cliffs. 17 analysis tools total — from Social Security optimization to geographic arbitrage to estate planning. Everything runs on-device with zero data collection. Would love to hear your feedback!

CoastIQ

The only retirement calculator that gets your taxes right

The only retirement calculator that gets your taxes right