Bangladesh Electricity Bill Calculator

A TypeScript library to calculate electricity bills in Bangladesh based on standard tariff structures (DESCO/NESCO/BPDB). It supports both stepped (slab-based) rates for residential users and flat rates for other categories.

Features

• Residential Calculation: Supports slab-based billing (LifeLine, 0-75, 75-200, etc.).
• Commercial & Other Types: Supports flat rates, off-peak, and peak rates (where applicable).
• Demand Charge: Automatically adds demand charges based on the consumer type.
• VAT: Automatically calculates 5% VAT.
• Rounding: Implements specific rounding logic used in Bangladesh bills.

Installation

npm install electric-bill-bd
# or
yarn add electric-bill-bd

Usage

Basic Example (Residential)

import { calculateBill, BILL_TYPE } from 'electric-bill-bd';

const bill = calculateBill({
  classType: BILL_TYPE.Residential, // "LT-A"
  unit: 100, // Consumed Units (kWh)
});

console.log(bill);
/*
Output:
{
  unitPrice: 574.5,   // Energy Cost
  demand: 42,         // Demand Charge
  vat: 30.825,        // 5% VAT
  total: 647.325,     // Total before rounding
  totalFinal: 647     // Final Payable Bill
}
*/

Supported User Types

Use BILL_TYPE constant to select the user category:

• Residential (LT-A)
• AgriculturalPumps (LT-B)
• RetailIndustry (LT-C1)
• Construction (LT-C2)
• Educational, Religious, Charitable, Hospitals (LT-D1)
• StreetLights, WaterPumps (LT-D2)
• BatteryCharging (LT-D3)
• CommercialOffice (LT-E)
• Temporary (LT-T)

Custom Load

You can specify the sanctioned load (defaults to 1 kW/HP if not specified):

const bill = calculateBill({
  classType: BILL_TYPE.CommercialOffice,
  unit: 500,
  load: 5, // 5 kW
});

How Calculation Works

1. Step Calculation: For residential users, the first 50 units (LifeLine) have a special rate if total consumption is <= 50. Otherwise, it uses a stepped slab system (0-75, 75-200, etc.).
2. Demand Charge: Fixed rate per kW/HP of load depending on the user category.
3. VAT: 5% of the (Energy Cost + Demand Charge).
4. Rounding: Total bill is rounded. If decimal part <= 0.3 it rounds down, otherwise it rounds up.

License

MIT