Practical Calculator Library
Calculators for numbers people check often
Find practical calculators and supporting notes for recurring topics such as ROAS, VAT, margin, break-even, and rate planning.
Related tools
ROAS Calculator
Calculate return on ad spend from ad cost and attributed revenue.
Open toolFlow
Tools and follow-up numbers stay connected
Related calculators and short explanations are placed close together so users can move naturally from one number to the next.
Guide
Short notes instead of long explanations
Each page focuses on the conditions and quick checks people usually need when reading a result.
Categories
Browse by topic
Each topic brings related calculators and short notes together.
Advertising and Marketing Calculators
Practical tools for ad spend, acquisition cost, and campaign performance decisions.
- Compare ROAS and CAC quickly
- Check profit thresholds before spending
Business Operations Calculators
Practical tools for VAT, break-even planning, and operating numbers used in daily business decisions.
- Review cash-oriented operating numbers
- Estimate revenue and cost structure
Sales and Margin Calculators
Tools for selling price, cost, fee rate, and profit planning across commerce channels.
- Estimate net margin after platform fees
- Avoid loss-making discounts
Related tools
Core tools that solve real tasks
Start with the numbers people check most often.
Advertising and Marketing Calculators
Advertisers, marketers, agencies, and small business owners
ROAS Calculator
Calculate return on ad spend from ad cost and attributed revenue.
Quick check
OpenCAC Calculator
Estimate customer acquisition cost from total marketing spend and new customers.
Quick check
OpenVAT Calculator
Split gross and net amount using a standard 10% VAT assumption.
Quick check
OpenMargin Calculator
Calculate fee, remaining profit, and margin rate from price, cost, and platform fee.
Quick check
OpenBreak-even Calculator
Calculate how many units you need to sell before fixed costs are covered.
Quick check
OpenFreelance Rate Calculator
Estimate a realistic hourly and daily rate from your income goal, expenses, and billable hours.
Quick check
OpenGuides
Short guides that explain the numbers
These guides explain assumptions, common mistakes, and how to read each result in practice.
Ad metrics to read alongside ROAS
ROAS is useful, but CTR, CPC, and CPA should be checked together before judging campaign efficiency.
What to confirm before calculating VAT
Check whether the amount is a total, a supply amount, or a tax amount before using the calculator.
Common mistakes when reading calculator results
The same number can mean something very different depending on period, fees, and tax assumptions.
Cost items to review before margin calculation
Margin estimates become more realistic when channel fees, payment fees, shipping, and returns are included.