FHA Calcs

Methodology

FHA calculator methodology

The exact assumptions used by the FHA payment, FHA MIP, and FHA vs conventional calculators.

Calculation scope

Version 1 supports 30-year fixed FHA purchase-loan estimates only. It does not handle 15-year loans, ARMs, refinance, streamline refinance, 203(k), county loan-limit checks, DTI, approval, or lender quotes.

Principal and interest

P&I uses the standard fixed-rate amortization formula over 360 months. Money is stored as integer cents or decimal arithmetic; display formatting is separate from the calculation core.

Upfront MIP

UFMIP is calculated from the HUD whole-dollar base loan using the 1.75% rate. The result is truncated to cents rather than rounded. If financed, UFMIP is added to the loan amount used for P&I, then floored to whole dollars.

Monthly FHA MIP

The MIP tier uses the floored base loan amount and original LTV. The current threshold in this implementation is $726,200 from HUD Mortgagee Letter 2023-05, last verified 2026-06-02. Monthly MIP uses the annual average outstanding balance by year and is cut off at 11 years when original LTV is 90% or less; otherwise it runs for the loan term.

Tax, insurance, HOA

Property tax, homeowner insurance, and HOA are user-editable assumptions. They are included in monthly totals but are not FHA underwriting values or local tax estimates.

FHA vs conventional

The comparison page uses editable FHA rate, conventional rate, PMI rate, PMI cancellation LTV, tax, insurance, HOA, and holding period assumptions. Holding-period FHA cost walks the yearly MIP schedule instead of repeating year-one MIP forever. Crossover is the first month conventional becomes cheaper after having been costlier under the entered assumptions. The page says “based on your assumptions” and does not recommend FHA or conventional financing.

Sources

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