Comprehensive financial calculations including future value, present value, discount/markup pricing, compound interest, and comparative tables.

Quick Start

CLI Usage

# Future Value
python3 scripts/calculate.py fv 10000 0.05 10 12
# PV=$10,000, Rate=5%, Years=10, Monthly compounding
# Present Value
python3 scripts/calculate.py pv 20000 0.05 10 12
# FV=$20,000, Rate=5%, Years=10, Monthly compounding
# Discount
python3 scripts/calculate.py discount 100 20
# Price=$100, Discount=20%
# Markup
python3 scripts/calculate.py markup 100 30
# Cost=$100, Markup=30%
# Future Value Table
python3 scripts/calculate.py fv_table 10000 0.03 0.05 0.07 --periods 1 5 10 20
# Principal=$10,000, Rates=3%,5%,7%, Periods=1,5,10,20 years
# Discount Table
python3 scripts/calculate.py discount_table 100 10 15 20 25 30
# Price=$100, Discounts=10%,15%,20%,25%,30%

Web UI

Launch the interactive calculator:

./scripts/launch_ui.sh [port]
# Default port: 5050
# Opens at: http://localhost:5050
# Auto-creates venv and installs Flask if needed

Or manually:

cd skills/financial-calculator
python3 -m venv venv  # First time only
venv/bin/pip install flask  # First time only
venv/bin/python scripts/web_ui.py [port]

Features:

• 7 calculator types with intuitive tabs
• Real-time calculations
• Interactive tables
• Beautiful gradient UI
• Mobile-responsive design

Calculators

1. Future Value (FV)

Calculate what an investment will be worth in the future with compound interest.

Use cases:

• Investment growth projections
• Savings account growth
• Retirement planning

Inputs:

• Principal amount
• Annual interest rate (%)
• Time period (years)
• Compounding frequency (annual/quarterly/monthly/daily)

2. Present Value (PV)

Calculate the current value of a future amount (discounted value).

Use cases:

• Loan valuation
• Bond pricing
• Investment analysis

Inputs:

• Future value
• Annual discount rate (%)
• Time period (years)
• Compounding frequency

3. Discount Calculator

Calculate final price after applying percentage discount.

Use cases:

• Retail pricing
• Sale calculations
• Cost savings analysis

Inputs:

• Original price
• Discount percentage

Outputs:

• Discount amount
• Final price
• Savings percentage

4. Markup Calculator

Calculate selling price from cost and markup percentage.

Use cases:

• Product pricing
• Profit margin calculation
• Business pricing strategy

Inputs:

• Cost price
• Markup percentage

Outputs:

• Markup amount
• Selling price
• Profit margin (as % of selling price)

5. Compound Interest

Detailed breakdown of compound interest calculations.

Use cases:

• Interest analysis
• Effective rate comparison
• Loan interest calculation

Outputs:

• Final amount
• Total interest earned
• Effective annual rate

6. Future Value Table

Generate comparison table across multiple rates and time periods.

Use cases:

• Investment scenario comparison
• Rate shopping
• Long-term planning

Features:

• Add multiple interest rates
• Add multiple time periods
• View all combinations in sortable table
• See total gain and gain percentage

7. Discount Table

Compare multiple discount percentages for the same price.

Use cases:

• Bulk pricing strategies
• Promotional planning
• Price comparison

Features:

• Add multiple discount percentages
• See all discount scenarios
• Compare final prices and savings

Installation

Requires Python 3.7+ and Flask:

pip install flask

Or with venv:

python3 -m venv venv
source venv/bin/activate
pip install flask

Python API

Import the calculation module:

from calculate import (
    future_value,
    present_value,
    discount_amount,
    markup_price,
    compound_interest,
    generate_fv_table,
    generate_discount_table
)
# Calculate FV
fv = future_value(
    present_value=10000,
    rate=0.05,  # 5% as decimal
    periods=10,
    compound_frequency=12  # Monthly
)
# Generate table
table = generate_fv_table(
    principal=10000,
    rates=[0.03, 0.05, 0.07],  # As decimals
    periods=[1, 5, 10, 20]
)

Formulas

See references/formulas.md for detailed mathematical formulas, examples, and use cases for all calculations.

Tips

Rate Format:

• CLI: Use decimals (0.05 for 5%)
• Web UI: Use percentages (5 for 5%)
• Python API: Use decimals (0.05 for 5%)

Compounding Frequencies:

• 1 = Annual
• 4 = Quarterly
• 12 = Monthly
• 365 = Daily

Table Generation: Best practices for meaningful comparisons:

• FV tables: Use 3-5 rates, 4-6 time periods
• Discount tables: Use 5-10 discount percentages
• Keep tables focused for easier analysis

Performance:

• Web UI calculations are instant
• Tables with >100 combinations may take a few seconds
• CLI is fastest for single calculations

Common Workflows

Investment Planning

• Use FV Calculator to project single investment
• Generate FV Table to compare different rates
• Check Compound Interest for detailed breakdown

Pricing Strategy

• Use Markup Calculator to set selling price
• Generate Discount Table to plan promotions
• Compare margins and final prices

Loan Analysis

• Use PV Calculator to value loan
• Check Compound Interest for total interest cost
• Generate FV Table to compare loan terms