Percentage Increase Decrease Calculator
Add or subtract a percentage from any value and get the new total with working shown.
Written by Golam Rabbani, Founder & Lead Engineer
How to use this percentage increase decrease calculator
- Choose Increase or Decrease using the toggle.
- Enter the starting value in the first field.
- Enter the percentage (without the % sign) in the second field.
- Press Calculate to see the new value and the change.
- Use Copy to put the result on your clipboard, or Reset to clear the inputs.
About this percentage increase decrease calculator
The percentage increase decrease calculator applies a percentage adjustment to a starting value and returns the new total. It handles both directions in one form, so you can mark a price up by a sales tax, take a discount off a bill, or model a percentage cut to a budget without switching tools.
The formula is new = value × (1 ± percent ÷ 100). The + sign applies for an increase and the − sign for a decrease. For example, increasing 250 by 15% gives 250 × (1 + 15 ÷ 100) = 250 × 1.15 = 287.5, an increase of 37.5. Decreasing 250 by 15% gives 250 × (1 − 15 ÷ 100) = 250 × 0.85 = 212.5, a decrease of 37.5. Both directions also show the absolute change (Δ) so you can see the actual amount added or subtracted.
This is the standard "add a percent" / "subtract a percent" calculation used for sale prices, tax adjustments, salary changes, and tip calculations.
FAQ
- What does the percentage increase decrease calculator do?
- It applies a percentage increase or decrease to any starting value and shows the new total along with the absolute change. Pick the direction with the Increase or Decrease toggle.
- What formula does this calculator use?
- new = value × (1 + percent ÷ 100) for an increase and new = value × (1 − percent ÷ 100) for a decrease. The absolute change shown is value × percent ÷ 100.
- What is the difference between this and percentage change?
- This tool starts with a value and a percentage and returns the new total. The percentage change tool starts with two values and returns the percentage difference. They are inverses of each other.
- Can I decrease a value by more than 100%?
- Yes — the calculator will not stop you, but the result will be negative. A 150% decrease of 100 returns −50, which is mathematically valid but rarely meaningful for prices or quantities.
- Does this tool store my numbers?
- No. Calculations run entirely in your browser; nothing is sent to a server or saved between visits.
- Is the calculator free?
- Yes. It is free to use with no signup, no account, and no usage limit.