Calculator Expert

Five calculators, done properly for Europe

Numbers you can actually trust.

Decimal-exact arithmetic, VAT rates that carry their legal source and check date, and every result shown with the formula underneath.

0floating-point errors
5languages & currencies
27+jurisdictions in the schema

VAT calculator

Add or remove VAT — sourced, dated rates for FR, ES, IT, PL & BG.

Multi-country

VAT-free day revealer

A “día sin IVA” at 21% is really 17.36% off. See the true saving.

Original

Percentage

X% of Y, X is what % of Y, and % change — instant.

Classic

Discount + cascade

50% then 20% is 60% off, not 70%. True combined rate.

Stacked

Margin vs markup

A 50% markup is a 33.3% margin — always shown together.

Trade
Reverse VATItaly · 22%
Gross €122,00
Net€100,00
Naïve “−22%”€95,16 ✕
÷ 1.22, never − 22%

Arithmetic that
actually holds up

Every figure runs on decimal maths, so cents never drift. Reverse VAT is a division, not a subtracted percentage — the difference banks and spreadsheets quietly get wrong.

0,00rounding error across 10,000 test pairs

Rates with a
paper trail

No hardcoded numbers. Each VAT rate carries the statute it comes from and the date we last checked it — and queries by date, so a 2019 invoice uses the 2019 rate.

5jurisdictions sourced & dated, schema for 27+
Standard rateFrance
20%
SourceCGI art. 278
Effective2014-01-01
Checked2026-07-14
“Día sin IVA”Spain · 21%
Real saving 17,36%
Advertised as21%
The gap3,64 pts

The number the
poster won’t show

A “VAT-free day” can’t legally drop VAT — the shop divides by 1.21. That’s a 17.36% discount, not 21%. We show the arithmetic plainly and let the reader draw the conclusion.

3,64points between the claim and the truth

Questions

Before you trust a number.

Why not just use a normal calculator?
Ordinary calculators use floating-point maths, where 0.1 + 0.2 doesn’t quite equal 0.3. On money that shows up as one-cent drift. Everything here runs on exact decimal arithmetic, so the totals reconcile.
How is “reverse VAT” different from taking off the percentage?
Subtracting 22% from a gross price is wrong. VAT was added by multiplying, so it comes off by dividing: €122 ÷ 1.22 = €100.00, not €95.16. Every tool here does it the correct way.
Where do the VAT rates come from?
A sourced, dated table — each rate names its statute (CGI, Ley 37/1992, DPR 633/1972…) and the date it was last verified. Rates are queried by date, so historical calculations use the rate that was in force then.
Which countries are covered?
France, Spain, Italy, Poland and Bulgaria are fully seeded and sourced at launch. The table’s structure covers all 27 EU states plus the UK and Switzerland, and more are added the same dated, sourced way.
Does anything I type get sent anywhere?
No. Every calculation happens in your browser, instantly, with no server round-trip. There’s nothing to submit and nothing to store.

Run the number.

Pick a calculator — it computes as you type, with the formula shown underneath.

Open the VAT calculator