How to Calculate Your FIRE Number — Step by Step

Introduction

Your FIRE number is the single most important figure in your financial life. It's the portfolio size that, once reached, can fund your lifestyle indefinitely without a paycheck. For a Polish FIRE seeker, the calculation isn't hard — but it does require honest accounting of expenses, realistic assumptions about Polish inflation (~3.5%), and awareness of local tax quirks (Belka tax, IKE/IKZE shields).

This guide walks through the calculation step by step, including adjustments specific to Poland. By the end, you'll have a number you can track monthly — and a plan for reaching it.

The Concept Explained with PLN Numbers

The FIRE number formula is simple:

FIRE number = Annual expenses × 25

The "25" comes from the 4% rule: if you withdraw 4% of a diversified portfolio per year, historical data suggests it can last 30+ years. 1 / 0.04 = 25.

Example:

• Monthly expenses: 6 000 PLN → annual: 72 000 PLN
• FIRE number: 72 000 × 25 = 1 800 000 PLN

That's the theoretical minimum at 4% SWR. For Polish conditions and early retirement (40+ years), a more conservative 3.5% SWR is safer:

72 000 / 0.035 = 2 057 000 PLN

Formulas and Calculations

Core formula:

FIRE number = Annual expenses / SWR

Step 1: Pin down real annual expenses. Go through 12 months of bank statements. Include:

• Housing (rent or mortgage + maintenance)
• Food + groceries
• Utilities
• Transport
• Insurance (health, car, life)
• Entertainment + subscriptions
• Vacation
• Kids (education, activities)
• "One-time" costs (car repair, appliances) — add 5–10% buffer

Step 2: Pick SWR.

Step 3: Apply Polish adjustments.

• Inflation: assume 3.5% long-run (NBP target is 2.5% ± 1%, but recent history runs hotter)
• Belka tax: 19% on gains outside IKE/IKZE — assume your real returns are 19% lower if holding in brokerage
• IKE (2026): annual contribution limit 26 019 PLN, tax-free withdrawals at 60
• IKZE (2026): 10 407 PLN, 10% flat tax on withdrawal but income-tax deduction now

Step 4: Add contingency.

• Add 6–12 months of expenses as an emergency buffer outside the FIRE number
• Add 10% to FIRE number for model error

Worked example — Polish family, 2 kids:

• Monthly expenses: 12 000 PLN → 144 000 PLN/year
• Horizon: 45 years (retire at 42, live to 87) → SWR 3.5%
• Base FIRE: 144 000 / 0.035 = 4 114 000 PLN
• +10% contingency: 4 525 000 PLN
• +12-month emergency fund: 144 000 PLN in bonds/cash (separate)

Comparison with Classic FIRE

Concrete Person Example

Aleksandra, age 36, Wrocław

• Net income: 14 500 PLN/month (product manager)
• Household expenses: 8 500 PLN/month with partner + 1 kid
• Her share of expenses: 4 500 PLN/month → 54 000 PLN/year
• Desired retirement age: 50 → horizon 40+ years → SWR 3.5%
• Current investments: 420 000 PLN across VWRA, IKE, IKZE, EDO bonds

FIRE number calculation:

• Base: 54 000 / 0.035 = 1 543 000 PLN
• +10% contingency: 1 697 000 PLN

Gap: 1 697 000 − 420 000 = 1 277 000 PLN in 14 years

• Required monthly investment at 6% real: ~5 100 PLN/month

She maxes IKE (26 019) + IKZE (10 407) = 36 426 PLN/year into tax-sheltered, then ~24 000 PLN into VWRA on XTB.

Risks and When It Makes Sense

Why your FIRE number might be too low:

• Expenses measured in a low-cost phase of life (pre-kids, pre-mortgage)
• Ignoring healthcare costs (Polish private clinics, dental, abroad)
• Assuming stable inflation when Poland has historically overshot

Why it might be too high:

• Double-counting ZUS/KRUS pension (kicks in at 60/65)
• Not planning to draw down principal (you can!)
• Over-conservatism on SWR (4% is fine for most people)

When the calculation works:

• Your expenses are stable and well-tracked for 12+ months
• You have a diversified portfolio (not 100% Polish stocks)
• You're comfortable with 10–20% volatility year to year

FAQ

Should I use 4% or 3.5% SWR? If you retire at 55+, use 4%. If you retire before 50, use 3.5%. Early retirement exposes you to more sequence-of-returns risk.

Do I include my house in the FIRE number? No — the FIRE number funds expenses. A paid-off house reduces expenses (no rent or mortgage) which reduces the number. Only include real-estate equity if you plan to sell it.

What about ZUS pension? Realistic Polish ZUS pension at 60+ is ~2 000–3 500 PLN/month. You can subtract that annuity's present value from your FIRE number, but many FIRE seekers ignore it as a buffer.

How often should I recalculate? Yearly, minimum. Also whenever life changes (kids, marriage, move, big career shift).

What if inflation spikes again? Your expenses drift up, your FIRE number drifts up. This is why you track it monthly — a moving target needs monitoring.

90-Day FIRE Number Calculation Plan

Days 1–30: Collect data

1. Export 12 months of every account to spreadsheet (bank, cards, cash notes)
2. Categorize expenses — be honest about "lifestyle" vs "necessary"
3. Identify seasonal and annual expenses (insurance, vacation, taxes)
4. Subtract one-time outliers (wedding, car purchase) — note separately
5. Calculate sustainable annual expenses (today's money)

Days 31–60: Run the numbers

1. Apply the 25x rule for 4% SWR baseline
2. Apply 28.6x for 3.5% SWR (conservative) — use if retiring before 50
3. Add 10% model error buffer
4. Separate emergency fund (6–12 months) — not part of FIRE number
5. Calculate gap: FIRE number − current net worth

Days 61–90: Plan the path

1. Determine required monthly contributions at 6% real return
2. Max out IKE + IKZE first (tax-sheltered compounding)
3. Choose brokerage + ETF strategy (VWRA via XTB is the default)
4. Install Freenance to track live progress
5. Set quarterly reviews and annual recalculation

Polish-Specific Adjustments

Healthcare uplift. Polish public healthcare is free via NFZ, but waiting lists are long. Budget 300–800 PLN/month for private medical packages (Medicover, Luxmed, Enel-Med).

ZUS pension offset. You'll likely get 1 800–3 500 PLN/month from ZUS after 60 (for today's 30–40 year olds). You can reduce your FIRE number by that annuity's present value, but many FIRE investors ignore it as a buffer.

Currency mix. If you plan to retire partially abroad (Spain, Portugal), hold 30–50% in EUR-denominated assets. If staying in Poland, 70–80% PLN exposure is normal.

Inheritance tax. If you plan to leave assets to kids, use IKE (tax-free inheritance in direct line) and structure accounts accordingly.

Track Your Freedom Runway

Calculating your FIRE number once is easy. Keeping it live — adjusting for inflation, spending changes, and portfolio growth — is the hard part. Freenance does it automatically. Connect your bank, XTB, Revolut, Binance, IKE/IKZE, and treasury bonds; Freenance shows your current Financial Freedom Runway in months, your FIRE date, and how each contribution moves the goalposts. 30-day free trial, no card required.

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