VAT and Percentage Questions Need the Right Base
KDV hesaplama and yüzde hesaplama searches often look simple, but many mistakes come from choosing the wrong base value. A 20 percent discount, a 20 percent price increase, and VAT included in a gross price are different calculations.
Before you calculate, decide what you are trying to find. Are you adding VAT to a net amount, extracting VAT from a gross amount, applying a discount, or comparing two numbers?
Net, VAT, and Gross Amounts
For a net price, VAT is added on top of the base. For a VAT-included gross price, VAT must be extracted from the total. These are not the same operation.
Use [Percent VAT](/percent-vat) when you need to move between net, tax, and gross amounts. Enter the known amount, choose the rate, and check which field the result represents.
Percentage Increase and Decrease
Percentage increase compares a new value against an old value. Percentage decrease works the same way, but the result shows a drop. The original value is the base.
For example, moving from 1,000 to 1,200 is a 20 percent increase. Moving from 1,200 to 1,000 is a 16.67 percent decrease. The lira difference is the same, but the base is different.
Use the [percentage calculator](/percentage-calculator) for increases, decreases, discounts, margins, and quick comparisons.
Discount and Markup Checks
A discount is usually taken from the listed price. A markup is usually added to cost. Mixing these up can make a margin look healthier than it is.
When you review a price, write the sequence clearly. Start with net price, add VAT, apply discount only if the business rule says the discount comes after VAT, and compare the final payable amount.
Practical Tips
- Label each amount as net, VAT, or gross.
- Keep the percentage rate separate from the currency amount.
- Check whether the price already includes VAT.
- Use the original value as the base for change calculations.
- Round only at the final step when possible.
Clear labels prevent most VAT and percentage errors. They also make the result easier to explain on invoices, offers, and internal notes.
