Free forever · No sign-up · No ads

Percentage Tools

Q: Why don't stacked discounts add up?

Because each discount applies to the already-reduced price. 30% off leaves 70% of the price; an extra 10% then takes 10% of that 70%, not of the original. Multiply what you pay: 0.70 × 0.90 = 0.63, i.e. 37% off — not 40%.

Q: How do I remove GST from a price that includes it?

Divide by (1 + rate ÷ 100), then subtract. For ₹1,180 at 18%: base = 1,180 ÷ 1.18 = ₹1,000, GST = ₹180. Don't subtract 18% of ₹1,180 (₹212) — GST is charged on the base, not the total.

Q: How do I convert CGPA to percentage?

CBSE's convention: indicative percentage = CGPA × 9.5. So 8.6 CGPA ≈ 81.7%. It's an approximation boards use for equivalence — universities may apply their own formula.

Q: What is a 'real' salary hike?

Your nominal hike minus the bite of inflation: real ≈ (1 + hike) ÷ (1 + inflation) − 1. An 8% hike at 6% inflation is only about 1.9% in real purchasing power.

Q: Percentage points vs percent — what's the difference?

Percentage points are the plain difference (25% − 20% = 5 pp). Percent change is relative to the starting value (5 ÷ 20 = 25%). A rate 'rising 25%' and 'rising 5 points' from 20% mean the same thing — but from 4%, a 25% rise is only 1 point.

Q: Where does my data go?

Nowhere. Every number on this page is computed in your browser — no server, no database, no tracking.

The percentages everyone gets wrong — stacked discounts, reverse GST, real salary hikes — plus the everyday ones, done right. Everything computes on your device.

Free forever No sign-up No ads Private by design

Airplane-mode test — disconnect Wi-Fi. It still works.

The calculator

Pick a tool

Six tools, one page — discounts, GST, marks, hikes, the traps, and the basics.

Price

Discount %

Extra discount %

Enter the price and a discount — results update as you type. Add a second discount to see stacking.

You pay

—

You save

—

Effective discount

—

How it stacks up

—

How it stacks up

Why it's not 40%

Good to know

These are general-education math tools, not financial or tax advice. GST slabs change — confirm the current rate for your item before filing anything.

GST mode

Amount

GST rate

Base price

—

GST amount

—

Total

—

Same-state sale: this splits into CGST + SGST (half each). Across states: it's IGST.

Marks obtained

Total marks

Percentage

—

CGPA (10-pt)

—

CBSE convention: indicative percentage ≈ CGPA × 9.5.

Percentage vs percentile

Percentage is your score out of 100. Percentile is the share of students you scored above — 90th percentile means you beat 90% of candidates, whatever the marks were.

Current annual CTC

Hike %

New CTC

—

Annual raise

—

Monthly raise

—

Inflation %

Real hike

—

After inflation — what your raise is actually worth.

Hike %

—

After inflation — what your raise is actually worth.

Successive changes

Start value

Change 1 %

Change 2 %

Change 3 %

Final value

—

Net change

—

How it stacks up

—

Successive changes

+10% then −10% is not back to zero — it's −1% net. Every change applies to the new amount, not the original.

Percentage points vs percent

From %

To %

Percentage points

—

Relative change

—

Percentage points vs percent

20% → 25% is +5 percentage points, but +25% in relative terms. Headlines usually mean the first; your wallet feels the second.

What is X% of Y?

X (%)

—

X is what % of Y?

—

% increase / decrease

From

—

Questions, answered

Why don't stacked discounts add up?

How do I remove GST from a price that includes it?

How do I convert CGPA to percentage?

What is a 'real' salary hike?

Percentage points vs percent — what's the difference?

Where does my data go?

Share this result

The link carries only your inputs — nothing else.

More tools

The same promise — free, private, no sign-up.