It depends on risk and alternatives. Many businesses look for a positive ROI and compare options on ROI plus payback time.

What if my ROI is negative?

A negative ROI means the return was less than the investment. The calculator will show a negative profit and ROI%.

Does ROI include time?

Basic ROI doesn’t account for time. For time-based growth, consider CAGR or compare ROI across the same time period.

Effective Discount Percentage

Find the effective discount percentage when multiple offers apply (e.g. discount + voucher). Useful for pricing and promotion analysis.

Use this calculator when you need a fast, reliable answer without opening a spreadsheet. Enter your figures below and press Calculate. PercentNinja shows the key outputs you typically need for pricing decisions, VAT checks, ecommerce payouts or ad reporting.

When to use this

Checking a price before you publish it on your website or marketplace
Planning profitability (margin, fees or VAT) before running ads
Quick sanity-checks for invoices, quotes or campaign reports

Calculate

Results are estimates for informational purposes only and may be rounded.

Tip: Press Enter to calculate.

Worked examples

Example 1

Question: Original £100, paid £72.

Discount = (100 − 72) ÷ 100 × 100 = 28%

Example 2

Question: Original £59.99, paid £49.99.

Discount ≈ (59.99−49.99)÷59.99×100 ≈ 16.67%

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