Do two successive 10% discounts add up to 20%?

No. Two successive 10% discounts result in 19% total. Calculation: $100 with first 10% off becomes $90. $90 with second 10% off becomes $81. Effective discount: 19% (not 20%). This is one of the most common financial math errors in retail.

Is the percent change from 50 to 100 equal to 50% or 100%?

100%. Change = ((100-50)/50) × 100 = 100%. It means the value doubled — a positive change of 100% is equivalent to multiplying by 2. A positive change of 200% multiplies by 3, and so on.

How to calculate compound interest with percentage?

Compound interest: V × (1 + i)^t, where i is the decimal rate (5% = 0.05) and t is the number of periods. Unlike simple interest (V × i × t), compound interest adds the return to the principal each period. Use the current Selic rate (Central Bank) as a minimum return benchmark for fixed income.

How to calculate salary adjustment together with income tax?

Gross increase doesn't translate to proportional net increase due to progressive income tax. A 10% increase in gross can result in a very different net amount. Combine this calculator with Quorify's Net Salary Calculator to see the real impact on take-home pay.

What's the difference between percentage points (p.p.) and percentage?

Percentage points (p.p.) is the absolute change between two percentages — if the Selic rate rose from 10% to 12%, it's an increase of 2 p.p. (not 20%). Percentage of the change would be 20% (because 2 over 10 is 20%). Media and financial markets use p.p. to avoid confusion.

How to calculate gross margin in %?

Gross margin % = ((Revenue - Cost) ÷ Revenue) × 100. Different from markup (which divides by cost, not revenue). A 50% margin means half of the revenue is gross profit; 100% markup means the price is double the cost (50% margin). Confusing the two is a classic pricing mistake.

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Percentage Calculator

8 modes: change, discount, markup, growth target.

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How to calculate percentage in different situations?

Por Quorify EditorialAtualizado em 3 de junho de 2026

Quorify's Percentage Calculator solves the 5 most common operations that appear in everyday life: percentage of a value, percent change between two numbers, value after increase, value after discount, and what percentage X represents of Y. The calculation runs in your browser. Designed for real situations: calculating store discounts, salary changes, loan interest, weight changes, percentage of target achieved. Part of the Quorify financial toolkit: combine with the Net Salary Calculator to calculate salary adjustments, with the ROI Calculator to evaluate percentage returns on investments, and with the BMI Calculator to track weight progress.

Casos

When to use

Calculate the real value of a product after a store discount (e.g., $199.90 with 30% off).
Verify salary adjustment: from current salary to proposed, what is the real percentage increase.
Track goal progress: still 23% short of target, how much is that in absolute value?
Calculate interest on a loan or monthly investment — percentage is the foundation.
Check restaurant bills: 10% tip on what amount and the total divided by how many people.

Método

How the calculation works

Percentage of a value: V × (P/100). Percent change between two values (X→Y): ((Y-X)/X) × 100 — positive is increase, negative is decrease. Value after increase: V × (1 + P/100). Value after discount: V × (1 - P/100). What % X is of Y: (X/Y) × 100. The tool automatically detects the type of calculation from the filled fields and shows the formula applied — useful for relearning the concept while solving the practical case. Classic pitfall: two successive discounts DO NOT add up — 10% + 10% is not 20% total discount, it's 19% (because the second 10% applies to the already-discounted value).

FAQ

Frequently asked questions

Do two successive 10% discounts add up to 20%?: No. Two successive 10% discounts result in 19% total. Calculation: $100 with first 10% off becomes $90. $90 with second 10% off becomes $81. Effective discount: 19% (not 20%). This is one of the most common financial math errors in retail.
Is the percent change from 50 to 100 equal to 50% or 100%?: 100%. Change = ((100-50)/50) × 100 = 100%. It means the value doubled — a positive change of 100% is equivalent to multiplying by 2. A positive change of 200% multiplies by 3, and so on.
How to calculate compound interest with percentage?: Compound interest: V × (1 + i)^t, where i is the decimal rate (5% = 0.05) and t is the number of periods. Unlike simple interest (V × i × t), compound interest adds the return to the principal each period. Use the current Selic rate (Central Bank) as a minimum return benchmark for fixed income.
How to calculate salary adjustment together with income tax?: Gross increase doesn't translate to proportional net increase due to progressive income tax. A 10% increase in gross can result in a very different net amount. Combine this calculator with Quorify's Net Salary Calculator to see the real impact on take-home pay.
What's the difference between percentage points (p.p.) and percentage?: Percentage points (p.p.) is the absolute change between two percentages — if the Selic rate rose from 10% to 12%, it's an increase of 2 p.p. (not 20%). Percentage of the change would be 20% (because 2 over 10 is 20%). Media and financial markets use p.p. to avoid confusion.
How to calculate gross margin in %?: Gross margin % = ((Revenue - Cost) ÷ Revenue) × 100. Different from markup (which divides by cost, not revenue). A 50% margin means half of the revenue is gross profit; 100% markup means the price is double the cost (50% margin). Confusing the two is a classic pricing mistake.

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Related tools

Fontes

Official sources

Tabelas, leis e referências consultadas para fundamentar esta ferramenta.

Official indicatorCOPOM updateCentral Bank of Brazil
Selic Rate — History and current
Basic interest rate of the Brazilian economy — benchmark for minimum return and opportunity cost calculations.
Consultar fonte oficial
Official tableEffective in 2026Brazilian Federal Revenue Service
Personal Income Tax Table
Progressive monthly and annual income tax table, tax brackets, deductions, and dependent deduction rules.
Consultar fonte oficial

Metodologia — esta ferramenta consulta as tabelas e legislação vigentes nas fontes acima. As regras são atualizadas conforme novas instruções normativas são publicadas pelos órgãos competentes.

Última verificação editorial: junho de 2026.

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