Toolbox
Every calculation. Zero guesswork.
Reliable accounting calculators organized into packs. Tax estimators, deduction calculators, payroll utilities, loan amortization, and more. No AI — just clean, repeatable math.
The Pack System
Start free. Add packs as your firm needs them.
Seven packs of accounting calculators. The Starter Pack is free — your gateway to the full collection. Buy individual packs by domain as your practice grows.
Starter Pack
FreeThe gateway. Essential calculators included free with every Cairn subscription. See how Toolbox works before you add a single paid pack.
Tax Pack
- Federal income tax estimator
- Quarterly estimated payments
- Capital gains calculator
- AMT worksheet
Deductions Pack
- Mileage deduction calculator
- Home office (simplified + regular)
- Section 179 depreciation
- Charitable contribution limits
Payroll Pack
- Net-to-gross calculator
- Employer cost calculator
- Federal withholding estimator
- Overtime calculator
Loans Pack
- Amortization schedule generator
- Loan comparison tool
- Interest rate converter
- Balloon payment calculator
Retirement Pack
- Required Minimum Distribution
- Social Security estimator
- Contribution limit reference
- Early withdrawal penalty
Business Pack
- Self-employment tax estimator
- Entity type comparison
- Quarterly payment scheduler
- Break-even analysis
The Difference
Tools produce numbers. Professionals provide counsel.
Toolbox is the math layer in a suite that also includes AI-powered apps. Here, every result is reproducible and verifiable. Same inputs, same answer, every time.
No AI
Every calculation produces the same result, every time. Same inputs, same outputs. No models, no probabilities, no "it depends." Run it twice — get the same answer twice.
No Advice
Toolbox produces numbers. What those numbers mean for a specific client is your expertise. The calculator tells you the mileage deduction — you decide if it applies.
Instant Results
Every calculator runs right in your browser. No waiting on servers, no connection required. Enter values, get results. The math is instant.
Clean inputs. Clear outputs.
Every calculator follows the same pattern: labeled fields, instant results, no clutter. Professional tools designed for speed — enter the numbers you know, get the answer you need.
Calculator packs
Individual calculators
AI dependencies
Ready to add Toolbox to your stack?
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