Sales Tax Calculator (Add or Remove GST)

About the Sales Tax Calculator

Pakistani invoices play a small trick: some quote prices without tax and add GST at the end, while others quote one tax-inclusive number and leave you to work out how much of it belongs to the taxman. This sales tax calculator handles both directions at any rate — 18% federal GST by default, or any provincial rate you type — and shows net, tax and gross with the working visible.

The two modes answer different questions. Adding tax is the shopkeeper's job: a customer owes 10,000 plus 18% GST, so the invoice reads 11,800. Removing tax is the buyer's audit: a bill says 11,800 tax-inclusive, and you need to know 10,000 was goods and 1,800 was tax — not the same as knocking 18% off the total.

Everything runs in your browser with nothing stored. Use it to draft invoices, to check a supplier's tax line before paying it, to separate GST for monthly filing, or to price a product so it lands at a round 10,000 after tax rather than before.

How to Use the Sales Tax Calculator

Follow these simple steps — the whole process takes under a minute:

1. Enter the amount — the net price if you are adding tax, or the tax-inclusive total if you are removing it.
2. Check the rate — 18% is the standard federal GST; type 16 for Punjab services PST or any other rate your invoice uses.
3. Choose the mode — Add tax for net to gross, Remove tax for gross to net; add is the default.
4. Press Calculate Tax — the net amount, the tax at your rate and the gross appear with the formula applied.
5. Reconcile the rows — net plus tax must equal gross on every correct invoice; if it does not, the rate or the base is wrong.

The Formula & Method Behind the Sales Tax Calculator

Adding tax is one multiplication: gross = net × (1 + rate ÷ 100). For a net amount of Rs. 10,000 at 18%, the multiplier is 1.18 and the gross is 10,000 × 1.18 = Rs. 11,800, of which 11,800 − 10,000 = Rs. 1,800 is the tax. Equivalently, tax = net × rate ÷ 100, so the tax line scales in exact proportion to the price.

Removing tax divides instead: net = gross ÷ (1 + rate ÷ 100). A Rs. 11,800 tax-inclusive bill at 18% is 11,800 ÷ 1.18 = Rs. 10,000 net, with Rs. 1,800 of tax inside it. The division is essential: simply subtracting 18% of 11,800 would give Rs. 9,676 and overstate the tax, because the tax was charged on the smaller net base, not on the gross.

The same engine handles any rate, because only the multiplier changes: at 16%, add mode turns Rs. 25,000 into 25,000 × 1.16 = Rs. 29,000 with Rs. 4,000 of tax, and remove mode recovers 29,000 ÷ 1.16 = Rs. 25,000. Rates in Pakistan are set by FBR notifications for federal GST and by the provincial revenue authorities for services, and they change — always confirm the current percentage against the latest notification before you invoice or file.

GST, PST and Invoices in Pakistan — What to Check

Know which tax applies. Goods generally carry the federal 18% GST administered by FBR, while services are taxed provincially — the Punjab Revenue Authority, Sindh Revenue Board, KPRA and BRA set their own rates, commonly around 15–16%, and one invoice can carry both lines for mixed supplies. The rate field accepts whatever your situation needs — check your provincial rate first.

Small businesses live on correct tax lines. A shop or sole proprietor registered for GST must charge it once registered, show it separately on the invoice, and deposit it on schedule — under-charging means paying the shortfall out of your own pocket. Run every draft invoice through add mode and every supplier bill through remove mode to keep input and output tax visible before filing day.

The classic mistake: subtracting the percentage. Removing 18% by computing 11,800 − 18% gives Rs. 9,676 and invents Rs. 324 of phantom tax; the true net is Rs. 10,000. The tax was calculated on 10,000, so only the division in remove mode reverses it. Whenever a tax-inclusive figure is quoted, divide — never subtract.

Verify rates against official notifications. FBR adjusts GST rates, thresholds and schedules through finance acts and SROs, and the provincial authorities follow their own calendars — treat any rate, including the default 18% here, as editable and confirm it against the latest notification before filing. For the other tax on your payslip, the salary tax calculator breaks down FBR's income-tax slabs, and the discount calculator untangles prices that drop before tax is applied.