What this calculator finds
This tool does one job well: it adds or subtracts a percentage from a number, instantly and exactly. Type a base value — a price, a salary, an invoice total, anything — and a percentage rate, pick Increase or Decrease, and get the new value plus the exact amount that changed.
The Batch List tab extends the same math to a whole set of numbers at once: paste a price list, a column of salaries, or a set of invoice lines, enter one percentage, and every row gets the same increase or decrease applied — with totals before and after. This is the quick way to answer searches like "X × 1.15" or "X × 0.85" for more than one number at a time.
Formula
For a 15% increase that's Base × 1.15; for a 15% decrease it's Base × 0.85. Swap in any rate — 5% is ×1.05 / ×0.95, 20% is ×1.20 / ×0.80, and so on.
Worked examples
75 × 1.15 = 86.25 — the amount added is 75 × 0.15 = 11.25.
150 × 0.85 = 127.50 — the amount removed is 150 × 0.15 = 22.50.
After +15%: 22.99, 39.68, 138, 10.06, 287.50 (new total 498.23) — every row increased by exactly 15%, no manual retyping.
Common ×1.XX and ×0.XX reference table
The same base numbers from the example above, run through the most frequently searched multipliers — 15 and 75 and 150 are the three most common bases people look up with ×1.15 and ×0.85.
| Base | +5% (×1.05) | +15% (×1.15) | −15% (×0.85) | +20% (×1.20) |
|---|---|---|---|---|
| 15 | 15.75 | 17.25 | 12.75 | 18 |
| 75 | 78.75 | 86.25 | 63.75 | 90 |
| 150 | 157.5 | 172.5 | 127.5 | 180 |
| 500 | 525 | 575 | 425 | 600 |
| 1,000 | 1,050 | 1,150 | 850 | 1,200 |
Need every value for a single rate spelled out in detail — including salaries and tax examples? See the complete ×1.15 reference table on the main Percentage Calculator.
When to increase vs. decrease
- Tips and service charges: add 15%–20% to a restaurant bill or service invoice.
- Raises and budgets: add a percentage to a salary, a project budget, or a savings goal.
- Markups and taxes: add a percentage to a wholesale cost or a pre-tax price.
- Discounts and sales: subtract a percentage from a listed price.
- Pay cuts or cost-cutting: subtract a percentage from a budget or expense line.
- Repricing a catalog: use Batch List to apply one increase or decrease to every item at once instead of recalculating each price by hand.
Percentage increase vs. percentage points
Be careful not to confuse a percentage increase (what this calculator does) with adding percentage points to a rate that is already a percentage. Increasing 200 by 15% gives 230 (200 × 1.15) — a relative, multiplicative change. But if an interest rate goes from 40% to 55%, that is a 15 percentage point increase, not a 15% increase (a true 15% increase on 40% would only reach 46%). This calculator always performs the relative percentage increase or decrease, which is what almost every price, salary or invoice calculation needs.
Frequently asked questions
How do I add a percentage to a number?
Multiply the number by (1 + percentage/100). To add 15% to 80, multiply 80 × 1.15 = 92. The shortcut works for any rate: add 5% by multiplying by 1.05, add 20% by multiplying by 1.20, and so on.
How do I subtract a percentage from a number?
Multiply the number by (1 − percentage/100). To subtract 15% from 80, multiply 80 × 0.85 = 68. Subtracting 20% means multiplying by 0.80, subtracting 5% means multiplying by 0.95.
What does multiplying by 1.15 or 0.85 actually mean?
×1.15 means "the original 100% plus an extra 15%" — it adds 15% in one step. ×0.85 means "the original 100% minus 15%" — it removes 15% in one step. Both are shortcuts for the full formula New Value = Base × (1 ± Percentage/100).
Can I apply the same percentage increase to a whole list of prices at once?
Yes — switch to the Batch List tab, paste your numbers (one per line, or separated by commas or spaces), enter the percentage once, and the calculator applies it to every value and totals the before/after amounts. This is useful for repricing a product catalog, applying a raise to several salaries, or adding tax to a list of invoice lines.
Is a 15% increase the same as adding 15 percentage points?
No. A 15% increase is relative to the starting value: 200 increased by 15% is 230 (200 × 1.15). Adding 15 percentage points to a rate that is already a percentage (e.g. a 40% rate becoming 55%) is a different, additive operation. This calculator performs the relative (multiplicative) percentage increase or decrease.
How is this different from the main Percentage Calculator?
The main Percentage Calculator has four general modes (find X% of Y, what percent X is of Y, percentage change between two numbers, and reverse percentage) built for one value at a time. This tool is focused specifically on the add/subtract-a-percentage operation and adds a Batch List mode to apply the same percentage to many numbers in one pass — handy when you have a whole price list, not just one number.
Is this percentage increase calculator free?
Yes, completely free with no sign-up. Everything runs instantly in your browser with JavaScript — your numbers are never uploaded or stored.