Tax Calculators: Every Formula Behind All 25 Tools (2026)

Tax calculators turn confusing tax rules into numbers you can actually use. Type in your income, pick your filing status, and you'll see what you owe in seconds. This guide covers all 25 tax calculators on Calcavio and, just as importantly, the exact formula behind each one. So you can check every result by hand.

Tax Calculators

What do tax calculators actually do?

A tax calculator applies official tax rates to the numbers you enter - income, filing status, deductions and returns an estimate of what you owe or take home. Good ones use current-year figures, show both marginal and effective rates, and never store your data. Calcavio's tools run entirely in your browser.

Each calculator below solves one specific question. As a result, you don't need to understand the whole tax code - just the formula for your situation. Let's walk through them, region by region.

How do US income tax calculators work?

Income Tax Calculator

Tax = Σ (income within each bracket × that bracket's rate)

For 2026, single filers pay 10% up to $12,400, 12% up to $50,400, 22% up to $105,700, 24% up to $201,775, then 32%, 35%, and 37% above $640,600 (IRS, Rev. Proc. 2025-32). For example, $60,000 of taxable income costs $1,240 + $4,560 + $2,112 = $7,912. Run your own numbers with the Income Tax Calculator.

Income Tax Calculator (2026)

Tax Bracket Calculator

Taxable income = gross income − deductions

then find the bracket holding your last dollar. The 2026 standard deduction is $16,100 (single) or $32,200 (joint). So a $70,000 salary leaves $53,900 taxable - the 22% bracket. Check yours with the Tax Bracket Calculator.

Tax Bracket Calculator (2026)

Marginal Tax Rate Calculator

Marginal rate = rate on your next dollar 

and 

Effective rate = total tax ÷ taxable income

From the example above, that's 22% marginal but only 13.2% effective. Big difference and the Marginal Tax Rate Calculator shows both.

Marginal Tax Rate Calculator (2026)

Paycheck Calculator

Net pay = gross − federal withholding − Social Security (6.2% up to $184,500 in 2026) − Medicare (1.45%) − state tax − pre-tax deductions

On a $5,000 monthly salary, FICA alone takes $382.50. See your take-home with the Paycheck Calculator.

Paycheck Calculator (2026)

W-4 Withholding Calculator

Annualize your wages, subtract deductions, compute tax through the brackets, subtract Step 3 credits, divide by pay periods, then add any Step 4 extra amount.

In short, it tells you what each paycheck should withhold. Fine-tune it with the W-4 Withholding Calculator.

W-4 Withholding Calculator (2026)

Marriage Tax Penalty / Bonus Calculator

Δ = tax filing jointly − (tax as single A + tax as single B)

A positive result is a penalty; a negative one is a bonus. Couples with uneven incomes usually score a bonus, because joint brackets are double the single ones through 32%. Test your situation with the Marriage Tax Calculator.

Marriage Tax Penalty / Bonus Calculator (2026)

What about self-employment and freelancer taxes?

Self-Employment Tax Calculator

SE tax = net profit × 92.35% × 15.3%

that's 12.4% Social Security plus 2.9% Medicare (IRS). On $80,000 of profit: $73,880 × 15.3% = $11,303.64. Half of it is deductible against income tax. Estimate yours with the Self-Employment Tax Calculator.

Self-Employment Tax Calculator (2026)

Quarterly Estimated Tax Calculator

Each payment = (expected annual tax × safe-harbor %) ÷ 4

The safe harbor is 100% of last year's tax (110% if AGI topped $150,000) or 90% of this year's, whichever you choose. Plan the four deadlines with the Quarterly Estimated Tax Calculator.

Quarterly Estimated Tax Calculator (2026)

1099 / Freelancer Tax Calculator

Total tax = SE tax + income tax on (profit − ½ SE tax − standard deduction)

In practice, it chains the two tools above. Take Sana, a freelance designer expecting $80,000 profit in 2026. SE tax is $11,304. Her taxable income drops to $58,248, so income tax adds $7,527. Total: about $18,830 - roughly $4,708 per quarter. The Freelancer Tax Calculator does that math in one pass.

1099 / Freelancer Tax Calculator (2026)

Which calculators cover investments, property, and estates?

Capital Gains Tax Calculator

Gain = sale price − cost basis

taxed at 0%, 15%, or 20% when held over a year. For 2026 single filers, 0% applies up to $49,450, 15% up to $545,500, and 20% above that (IRS). A $10,000 long-term gain in the 15% band costs $1,500. Short-term gains use ordinary brackets instead. Try the Capital Gains Tax Calculator.

UK Capital Gains Tax Calculator

Sales Tax Calculator

Tax = price × rate

So, 

Total = price × (1 + rate)

A $250 purchase at 7.5% comes to $268.75. There's no federal sales tax - rates are set by states and cities. Add or strip tax with the Sales Tax Calculator.

Sales Tax Calculator

Property Tax Calculator

Tax = assessed value × (mill rate ÷ 1,000)

A $350,000 home at 18 mills owes $6,300 a year. Estimate yours with the Property Tax Calculator.

Property Tax Calculator

Estate Tax Calculator

Taxable estate = gross estate − $15,000,000 exemption (2026)

with graduated rates from 18% to 40%. A $16M estate leaves $1M exposed about $345,800 under the full rate table. Model it with the Estate Tax Calculator.

Federal Estate Tax Calculator (2026)

Asset / Property Depreciation Calculator

Straight-line formula: 

Annual depreciation = (cost − salvage value) ÷ useful life

A $30,000 asset with $5,000 salvage over five years writes off $5,000 per year. Run it in the Depreciation Calculator.

Asset / Property Depreciation Calculator

MACRS Depreciation Calculator

Deduction = cost basis × MACRS table %

using 200% declining balance with the half-year convention. Year one on 5-year property is 20%: that same $30,000 asset deducts $6,000 immediately. Compare methods with the MACRS Depreciation Calculator.

MACRS Depreciation Calculator

How do the UK tax calculators work?

UK Income Tax & NI Calculator

Tax the income above the £12,570 personal allowance at 20% up to £50,270, 40% up to £125,140, and 45% beyond

with the allowance tapering £1 per £2 over £100,000 (HMRC, 2026/27). A £40,000 salary owes £5,486 in income tax. Get both figures at once with the UK Income Tax & NI Calculator.

UK Income Tax & NI Calculator

UK National Insurance Calculator

Employee Class 1 NI = 8% on earnings between £12,570 and £50,270, plus 2% above

That same £40,000 salary pays £2,194.40. Self-employed Class 4 uses 6% and 2% instead. Check it with the UK National Insurance Calculator.

UK National Insurance Calculator

UK Stamp Duty (SDLT) Calculator

Banded, like income tax — 0% to £125,000, 2% to £250,000, 5% to £925,000, 10% to £1.5m, 12% above.

First-time buyers pay 0% up to £300,000 on homes worth £500,000 or less, and additional properties add a 5% surcharge. A £400,000 home owes £2,500 + £7,500 = £10,000. Price a move with the UK Stamp Duty Calculator.

UK Stamp Duty (SDLT) Calculator

UK Capital Gains Tax Calculator

CGT = (gain − £3,000 annual exempt amount) × 18% or 24%

depending on your income band (GOV.UK, 2026/27). A basic-rate taxpayer with a £13,000 gain pays £1,800. Work it out with the UK Capital Gains Tax Calculator.

UK Capital Gains Tax Calculator

UK VAT Calculator

Two formulas:

1. add VAT with net × 1.20; 

2. extract it with gross × 1/6

So £100 becomes £120, and a £120 receipt hides £20 of VAT. Flip between them with the UK VAT Calculator.

UK VAT Calculator

UK Inheritance Tax Calculator

IHT = (estate − £325,000 nil-rate band − up to £175,000 residence band) × 40%

or 36% when 10%+ goes to charity. A £600,000 estate with the home passing to children owes £40,000. Plan ahead with the UK Inheritance Tax Calculator.

UK Inheritance Tax Calculator

What about Canada, Australia, and international VAT?

Canadian Income Tax Calculator

Sum the federal brackets, then subtract the basic personal amount credit.

For 2026: 14% to $58,523, 20.5% to $117,045, 26% to $181,440, 29% to $258,482, and 33% above (CRA). A $70,000 income owes about $8,243 federally before provincial tax. Estimate both layers with the Canadian Income Tax Calculator.

Canadian Income Tax Calculator

Australian Income Tax Calculator

nil to $18,200, then 16% to $45,000, 30% to $135,000, 37% to $190,000, and 45% above — plus the 2% Medicare levy (ATO, 2025–26).

A $90,000 income owes $17,788 + $1,800 levy = $19,588. Check your bracket with the Australian Income Tax Calculator.

Australian Income Tax Calculator

Australian GST Calculator

add GST with price × 1.1; extract it with total ÷ 11

A $200 sale becomes $220, and a $220 receipt contains exactly $20 of GST. Switch directions with the Australian GST Calculator.

Australian GST Calculator

International VAT / GST Calculator

gross = net × (1 + rate) 

and 

VAT inside a price = gross × rate ÷ (1 + rate)

EU standard rates run from 17% to 27%, so the same €100 item costs €117 in Luxembourg but €127 in Hungary. Compare countries with the International VAT / GST Calculator.

International VAT / GST Calculator

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