How to Calculate Your Electricity Bill 2026: Formula + Worked Example (Home, MEA/PEA)
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.
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 (new rates from the September 2569/2026 bill — for >150 units/month: the first 200 units cost 3.0000 THB, units 201–400 cost 4.1584 THB, units 401+ cost 4.3583 THB). See all tiers at how many baht per unit 2026, or enter your bill in the bill analyzer to compute it automatically. Renting a dorm or a room? Your landlord's bill is calculated differently from this page — a flat rate times metered units, with no tiers, no Ft and no service charge. The method and how to compare the gap are at how to calculate a dorm or rental electricity bill. Don't want to do the math? Enter your monthly units in the electricity bill calculator for an instant bill with the full per-tier breakdown (official MEA/PEA rates + current-period Ft, free).
The Home Bill Formula Has 4 Parts
Before calculating, you need your units — if you can't yet read the meter itself, start with how to read your electricity meter (dial/digital). Then 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. **These are the new rates, in force from the September 2569 (2026) electricity bill onward** (ERC resolution of 5 Aug 2569 — sources: the MEA Type-1 residential tariff table and the PEA September 2569 tariff document, checked 8 Sep 2026). For homes using >150 units/month: first 200 units at 3.0000, units 201–400 at 4.1584, units 401+ at 4.3583 THB (homes using ≤150 units are cheaper, starting at 2.3488 and never above 3.0000). 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 (Sep–Dec 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 >200 units (Cat 1.2) = 24.62 THB; homes using ≤200 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 (Sep–Dec 2026 figures):
Figures approximate the MEA/PEA Sep–Dec 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. Note: the Type 1.2 monthly service charge used to be 38.22 THB before the January 2023 (2566) billing cycle, when ERC resolution 51/2565 reduced it; it now stands at 24.62 THB, equal for both MEA and PEA. If you see 38.22 elsewhere, it is pre-2023 data — details in PEA vs MEA: is the bill different?. And if your home is on a TOU meter, the tiered formula above does not apply: you must split the units by time window first — see the 2026 On-Peak / Off-Peak time table.
How Do You Calculate a PEA (Provincial) Electricity Bill?
Calculating a PEA (Provincial Electricity Authority) bill uses exactly the same formula as this page, because the PEA's residential rates are identical to the MEA's to the baht — the same tiers, the same Ft of 0.1623 THB/unit, the same 24.62 THB monthly service charge (Cat 1.2) and the same 7% VAT. The ERC sets one national rate structure; the authorities do not price independently. The only difference is the service area: the MEA covers Bangkok, Nonthaburi and Samut Prakan; the PEA covers the other 74 provinces. Full reasoning at PEA vs MEA: is the bill different?.
Is Calculating an MEA (Metro) Bill Different from a PEA One?
No. Calculating an MEA bill uses the same formula and the same rate set. If your home is in Bangkok, Nonthaburi or Samut Prakan you are in MEA territory; everywhere else in the country is PEA (Provincial Electricity Authority). The 300-unit example above therefore produces the same total under either authority. The quickest check is the authority name printed at the top of your bill.
How Much Is a 300-Unit Bill? Home Bill Table 2026 (200–600 Units)
Approximate total bill for a Cat 1.2 home (over 200 units/month), from the same formula as the example above — tiered energy + Ft 0.1623 + 24.62 THB service charge + 7% VAT. Applies to both PEA and MEA:
| Units per month | Total bill (THB) | Effective THB/unit |
|---|---|---|
| 200 | 703.08 | 3.52 |
| 250 | 934.24 | 3.74 |
| 300 | 1,165.39 | 3.88 |
| 350 | 1,396.55 | 3.99 |
| 400 | 1,627.71 | 4.07 |
| 450 | 1,869.57 | 4.15 |
| 500 | 2,111.41 | 4.22 |
| 600 | 2,595.11 | 4.33 |
Your usage not in the table? Enter it yourself in the 2026 electricity bill calculator for an instant total with the full step-by-step breakdown (official rates, free). Homes using 200 units/month or less are Cat 1.1 and pay less than this table (service charge 8.19 THB) — see every tier at how many baht per unit.
Don't Want to Do the Maths? Use the Bill Calculator
Enter your monthly units and CapSolar's 2026 electricity bill calculator computes the tiered energy charge, Ft, service charge and VAT automatically (official rates, free) — for a factory or building bill, use the factory bill analyzer instead, which also 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.
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