PreppTools

Reference

Formula Cheat Sheets

Quick reference formulas for finance, tax, math, and health. Bookmark this page — you'll use it again.

Finance FormulasTax Formulas (India)Math & PercentageHealth & Fitness

Finance Formulas

→ EMI Calculator

EMI (Loan)

EMI = [P × r × (1+r)ⁿ] / [(1+r)ⁿ − 1]
  • • P = Principal loan amount
  • • r = Monthly interest rate (annual rate ÷ 12 ÷ 100)
  • • n = Loan tenure in months

Example: ₹10L loan, 8.5% p.a., 20 years → EMI ≈ ₹8,678/month

SIP Maturity Value

M = P × [(1 + r)ⁿ − 1] / r × (1 + r)
  • • P = Monthly SIP amount
  • • r = Monthly return rate (annual ÷ 12 ÷ 100)
  • • n = Number of months

Example: ₹5,000/month for 10 years @ 12% p.a. → ≈ ₹11.6L

Compound Interest

A = P × (1 + r/n)^(n×t)
  • • P = Principal
  • • r = Annual interest rate (decimal)
  • • n = Compounding frequency per year
  • • t = Time in years

Example: ₹1L @ 8% compounded monthly for 5 years → ₹1,48,978

Simple Interest

SI = (P × R × T) / 100
  • • P = Principal
  • • R = Annual rate (%)
  • • T = Time in years

FD Maturity (Quarterly Compounding)

M = P × (1 + r/4)^(4×t)
  • • P = Deposit amount
  • • r = Annual rate (decimal)
  • • t = Time in years

Tax Formulas (India)

→ GST Calculator

GST Inclusive Price → Base Price

Base Price = Inclusive Price / (1 + GST rate/100)

Example: Price ₹118 with 18% GST → Base = 118/1.18 = ₹100

GST Exclusive Price → Total Price

Total = Base Price × (1 + GST rate/100)

Example: ₹100 + 18% GST = ₹100 × 1.18 = ₹118

GST Amount

GST = Base Price × GST rate / 100

Income Tax (New Regime FY 2025-26)

Slab rates: 0–4L: 0% | 4–8L: 5% | 8–12L: 10% | 12–16L: 15% | 16–20L: 20% | 20–24L: 25% | >24L: 30%
  • • Add 4% cess on tax
  • • 87A rebate up to ₹25,000 if income ≤ ₹12L

TDS on Salary

TDS = (Estimated Annual Tax) / 12
  • • Employer deducts this monthly from salary

Math & Percentage

→ Percentage Calculator

Percentage of a Number

Result = (Percentage / 100) × Number

Example: 15% of 200 = (15/100) × 200 = 30

What % is X of Y?

% = (X / Y) × 100

Example: 30 is what % of 200? = (30/200) × 100 = 15%

Percentage Increase

% Increase = [(New − Old) / Old] × 100

Example: Price went from ₹80 to ₹100 → (20/80) × 100 = 25% increase

Percentage Decrease

% Decrease = [(Old − New) / Old] × 100

Discount Price

Final Price = Original × (1 − Discount% / 100)

Example: ₹500 with 20% off = 500 × 0.80 = ₹400

Profit / Loss %

Profit% = [(SP − CP) / CP] × 100
  • • SP = Selling Price
  • • CP = Cost Price

Health & Fitness

→ BMI Calculator

BMI

BMI = Weight (kg) / Height² (m²)
  • • <18.5: Underweight
  • • 18.5–24.9: Normal
  • • 25–29.9: Overweight
  • • ≥30: Obese

Example: 70 kg, 1.75 m → BMI = 70 / (1.75²) = 22.9 (Normal)

BMR (Mifflin-St Jeor)

Men: BMR = 10W + 6.25H − 5A + 5 Women: BMR = 10W + 6.25H − 5A − 161
  • • W = Weight (kg)
  • • H = Height (cm)
  • • A = Age (years)

TDEE (Total Daily Energy Expenditure)

TDEE = BMR × Activity Factor
  • • Sedentary: × 1.2
  • • Light active: × 1.375
  • • Moderate: × 1.55
  • • Very active: × 1.725

Max Heart Rate

Max HR = 220 − Age

Example: Age 30 → Max HR = 190 bpm

Ideal Body Weight (Devine Formula)

Men: 50 + 2.3 × (height in inches − 60) Women: 45.5 + 2.3 × (height in inches − 60)

Daily Water Intake

Water (litres) = Weight (kg) × 0.033

Example: 70 kg → 70 × 0.033 = 2.3 litres/day

Browse All Calculators →Glossary of Terms →