Retirement Methodology
How each calculator works: constants, formulas, assumptions, and what we don’t cover.
Pages in this section
401(k) Contribution Limit 2026 — Methodology, Constants, and Sources
This page documents the constants and calculation steps used by our 401(k) calculator and guide.
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401K Contribution Limit Calculator 2026 - Methodology & Sources
Transparent explanation of formulas, constants, and IRS data sources used.
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HSA Contribution Limit Calculator 2026: methodology
Formulas, constants, and sources used for this calculator.
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Roth Ira Income Limit Calculator 2026 - Methodology & Sources
Transparent explanation of formulas, constants, and IRS data sources used.
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Roth IRA Income Limit Calculator 2026: methodology
Formulas, constants, and sources used for this calculator.
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