How is the Ft calculated — is it multiplied across all units?

Yes — the Ft = total units × the current Ft rate (May–Aug 2026 = 0.1623 THB/unit). For example, 300 units = 300 × 0.1623 = 48.69 THB. The Ft is adjusted every 4 months; read the background at what the Ft is.

What are tiered rates, and why do later units cost more?

Homes aren't billed at one flat rate — they're split into tiers. For >150 units/month: the first 150 units are 3.2484 THB, units 151–400 rise to 4.2218 THB, and 401+ are 4.4217 THB. So the more you use, the higher your average per-unit cost. See all tiers at how many baht per unit.

About how much does a home using 300 units pay?

About 1,291.96 THB (energy 1,120.53 + Ft 48.69 + service 38.22 + 7% VAT 84.52), an effective ~4.31 THB/unit, using the MEA/PEA May–Aug 2026 rates. A real bill may vary slightly. Use the bill analyzer to compute from your own units.

Which part of the bill does solar reduce?

Solar directly cuts "the units you buy from the grid," which lowers both the energy charge and the Ft (both billed per unit) at once, because units you self-generate pay no Ft. Homes with heavy daytime use benefit most. See the big picture in the Thailand electricity guide.

Home Bill Formula

How to Calculate Your Electricity Bill 2026: Formula + Worked Example (Home, MEA/PEA)

Name: CapSolar
Address: 429/44 Sukhonthasawat Rd, Lat Phrao, Bangkok, 10230, TH
Telephone: +66 2 124 5414
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Want to know how your home electricity bill is built up? This page breaks the home formula down step by step — progressive energy tiers + the Ft + service charge + 7% VAT, with a 300-unit home example computed line by line, then plug in your own numbers in the bill analyzer.

5 min readData as of: current Ft period May–Aug 2026

How to calculate a Thai home bill: total = (progressive energy charge) + (Ft 0.1623 THB × units) + (monthly service charge), then add 7% VAT on the whole subtotal. Homes use a "tiered" energy charge — the more you use, the more the top units cost (for >150 units/month: the first 150 units cost 3.2484 THB, units 151–400 cost 4.2218 THB, units 401+ cost 4.4217 THB). See all tiers at how many baht per unit 2026, or enter your bill in the bill analyzer to compute it automatically.

The Home Bill Formula Has 4 Parts

Before calculating, know the 4 components that make up a home bill (MEA for Bangkok–Nonthaburi–Samut Prakan / PEA for other provinces):

1. Energy charge (tiered)

Based on units (kWh) used × a tiered per-unit rate. For homes using >150 units/month: first 150 units at 3.2484, units 151–400 at 4.2218, units 401+ at 4.4217 THB (homes using ≤150 units are cheaper, starting at 2.3488). See the full rates at how many baht per unit.

2. The Ft (variable charge)

A fuel cost the ERC adjusts every 4 months. The current period (May–Aug 2026) is 0.1623 THB/unit, multiplied across "every" unit you use. Read what the Ft is.

3. Monthly service charge

A fixed monthly fee. Homes using >150 units (Cat 1.2) = 38.22 THB; homes using ≤150 units (Cat 1.1) = 8.19 THB. Independent of how many units you use.

4. VAT (7%)

7% applied to the subtotal (energy + Ft + service charge) as the final line of the bill.

Worked Example: A Home Using 300 Units/Month

A home using 300 units/month falls in Cat 1.2 (>150 units). Step by step (May–Aug 2026 figures):

First 150 units × 3.2484 = 487.26 THB

Units 151–300 (150 units) × 4.2218 = 633.27 THB

Base energy subtotal = 1,120.53 THB

Ft: 300 units × 0.1623 = 48.69 THB

Monthly service charge = 38.22 THB

Subtotal before VAT = 1,207.44 THB

VAT 7% = 84.52 THB

Total bill ≈ 1,291.96 THB → effective ≈ 4.31 THB/unit

Figures approximate the MEA/PEA May–Aug 2026 rates; an actual bill may vary slightly by area and service charge. To compute quickly from your own bill, enter the numbers in the bill analyzer.

Don't Want to Do the Maths? Use the Bill Analyzer

Enter your units used and user type, and CapSolar's bill analyzer computes the tiered energy charge, Ft, service charge and VAT automatically — and estimates how much solar could save you.

About this page

Compiled by the CapSolar team, led by Frank Lee (Founder). Every formula and rate is cross-checked against official sources (ERC/MEA/PEA) and kept current to the latest Ft period. This page is general information, not personal advice — confirm the latest rates on your bill and with your local electricity authority.

FAQ

Yes. The formula is: total = tiered energy charge + (Ft 0.1623 × units) + monthly service charge, then add 7% VAT on the subtotal. See the 300-unit example on this page, or enter your numbers in the bill analyzer.

Want a lower home electricity bill?

Rooftop solar cuts the units you buy from the grid. CapSolar assesses for free whether it pays off for your home or building.

Talk to CapSolaror call +66 2 124 5414