VAT calculations usually involve two different tasks: adding VAT to a net amount or extracting VAT from an amount that already includes it.
These operations require different formulas.
The LUKIK VAT Calculator uses a rate entered by the user. It does not decide which legal VAT rate applies to a particular transaction, product, service or jurisdiction.
The rates below are arithmetic examples only.
Net amount, VAT amount and gross amount
Let:
X = amount;
R = VAT rate in percent.
If the starting amount is net, VAT is calculated from that base and added.
If the starting amount is already gross, the calculation needs to recover the original base.
How to add VAT
VAT amount:
VAT = X × R / 100
Gross amount:
Gross = X + VAT
or:
Gross = X × (1 + R / 100)
Example
Net amount:
1,000
Illustrative rate:
20%
VAT:
1,000 × 20 / 100 = 200
Gross amount:
1,000 + 200 = 1,200
Therefore:
net = 1,000
VAT = 200
gross = 1,200
How to extract VAT from a gross amount
Suppose the value 1,200 already includes VAT at an illustrative 20% rate.
It would be incorrect to simply calculate 20% of 1,200 because the rate was originally applied to the net amount.
Formula:
Net = Gross × 100 / (100 + R)
Then:
VAT = Gross − Net
Example
Gross amount:
1,200
Rate:
20%
Net amount:
1,200 × 100 / 120 = 1,000
VAT:
1,200 − 1,000 = 200
Why 20% of the gross amount is not the VAT amount
20% of 1,200 is:
240
But the VAT component in the example is 200.
The gross amount consists of:
1,000 net + 200 VAT
The 20% was applied to 1,000, not to 1,200.
Comparison examples
For a net amount of 1,000:
| Illustrative rate | VAT | Gross |
|---|---|---|
| 5% | 50 | 1,050 |
| 10% | 100 | 1,100 |
| 20% | 200 | 1,200 |
The reverse calculation restores the same net amount:
1,050 at 5% → 1,000 net
1,100 at 10% → 1,000 net
1,200 at 20% → 1,000 net
These examples explain the mathematics only.
Using the LUKIK VAT Calculator
First decide whether your starting amount already includes VAT.
For a net amount, choose the add-VAT mode.
For a VAT-inclusive amount, choose the extract-VAT mode.
Enter the amount and rate, and the calculator displays the relevant net, VAT and gross values.
Calculate VAT → LUKIK VAT Calculator
Common mistakes
Using the wrong base
When adding VAT, the percentage applies to the net amount.
When extracting VAT, the starting amount is already gross and requires the reverse formula.
Assuming the calculator chooses the applicable tax rate
It does not.
The user supplies the percentage, and the calculator performs the arithmetic.
Confusing net and gross values
Before calculating, answer one question:
Does this amount already include VAT?
Treating the result as legal or tax advice
The calculator decomposes values mathematically.
Actual tax treatment may depend on applicable rules and the nature of the transaction.
Conclusion
To add VAT:
VAT = X × R / 100
Gross = X × (1 + R / 100)
To extract VAT:
Net = Gross × 100 / (100 + R)
VAT = Gross − Net
The LUKIK VAT Calculator performs both calculations using the rate supplied by the user.
FAQ
Does the calculator use a fixed VAT rate?
No. The rate is entered by the user.
Why can’t I simply calculate the percentage of the gross amount?
Because the gross amount already contains VAT. The net base must be recovered first.
Can I enter another rate?
Yes. The mathematical calculation uses the user-entered rate.
Does the calculator determine the legally applicable VAT rate?
No. It performs arithmetic only.