What a Seoul Winter Gas Bill Actually Costs: ₩57,000–₩180,000 a Month, By House

A winter gas bill for a shared house in Seoul runs ₩57,000 to ₩180,000 a month on average per house — and hit as high as ₩299,770 in one house's worst January — based on our own records across 14 SharedHomies houses, November 2025 through March 2026. Split across housemates, that's roughly ₩19,000 to ₩71,000 a month per person for gas alone, before electricity. The reason it swings so hard: ondol (온돌) floor heating pumps gas-heated water under the floor all winter, and Seoul's coldest stretch pushed the average house's gas bill to about 6.8 times its summer level. Here's what we saw, house by house, and what's included in rent.

How does ondol (온돌) floor heating actually work?

Ondol literally means "warm stone" — Korea's underfloor heating tradition, adapted for modern apartments and share houses. A gas boiler (보일러) heats water to roughly 40–60°C and circulates it through loops of pipe embedded under the floor, warming the whole surface evenly and radiating heat upward into the room. That's a lower water temperature than a radiator system needs, and it's why gas-fired underfloor heating runs at roughly 90% gas-to-heat efficiency versus about 40% for a plug-in electric space heater — more of the fuel actually ends up as heat in your floor instead of being lost (how Korean floor heating works).

The same boiler usually does double duty — floor heating and the hot water for your shower and kitchen sink run off the same unit. That's why a "heating" bill and a "hot water" bill are really the same 도시가스 (city gas) line item on a Korean utility bill, and why a housemate who showers twice a day in January shows up on the same meter as the person who leaves the ondol dial turned up overnight.

What did our own winter gas bills actually look like?

This is the part most Seoul housing content can't show you, because it isn't public data — it's what we actually paid.

Across those 12 shared houses, the winter monthly average ranged from ₩56,958 (HONG1, our cheapest) to ₩179,652 (KLD1, our most expensive) — and KLD1's single worst month, January 2026, hit ₩299,770 on its own. Divided by housemates, that's a per-person gas share of roughly ₩19,000 to ₩71,000 a month, gas only.

Why is one house's gas bill so much higher than another's?

Same city, same fuel, same season — different bills. The gap between HONG1's ₩57,000 winter average and KLD1's ₩180,000 comes down to a few things we can actually see in the data and the buildings themselves: unit size and how many rooms run their own ondol zone independently, building age and insulation (older brick low-rises lose heat faster than newer builds), floor level (top-floor units lose more heat through the roof), and how many housemates are actually home running the floor heating during the day versus just overnight. None of it is about which gas company serves the address — see below.

How much more does gas cost in winter than summer in Seoul?

We pulled the same houses' summer bills (June–September 2025) for a straight before-and-after comparison. Across the portfolio, the average house paid ₩18,400 a month for gas in summer and ₩125,700 a month in winter — about 6.8 times more. January and February were consistently the two priciest months; some houses peaked in January, others in February, and March stayed close behind.

How does the actual gas bill get sent and paid in Korea?

City gas (도시가스) in Seoul is billed monthly by one of two regional providers depending on your address — Yesco or 서울도시가스 (Seoul City Gas) — based on metered usage, not a flat rate. Providers issue the bill through their own app, a KakaoTalk channel (가스톡), or a paper/PDF statement, and payment usually runs through a 가상계좌 (a dedicated virtual bank account number unique to that bill) or bank/card autopay (자동이체) registered to a Korean bank account (Seoul City Gas payment methods, Yesco billing lookup).

At SharedHomies, you don't have to set any of that up yourself. Bills land around the 10th of each month; Steve checks them against the account and posts a screenshot — address, account number, amount, all visible — to the house's WhatsApp or KakaoTalk group by the 11th or 12th, so anyone can verify it against the meter themselves rather than take a number on faith.

How do you stop 결로 (condensation) and mold when the ondol runs all winter?

Ondol heats the floor and air, but Seoul's winter air is dry outside and your exhaled breath, showers, and cooking add moisture inside — so warm, humid indoor air condenses fast against cold window glass and exterior walls. That's 결로 (gyeollo), and left alone it turns into mold within weeks.

• Crack a window for 5–10 minutes daily, even when it's freezing outside — brief full ventilation clears humidity faster than leaving a window cracked all day, which just wastes the heating you're paying for.
• Keep furniture a few centimeters off exterior walls so air can circulate behind it; a wardrobe pushed flush against a cold outside wall is the single most common spot we see mold start.
• Wipe condensation off window sills and frames in the morning — that pooled water is what soaks into paint and grout.
• Don't dry laundry indoors without ventilation. A rack of wet clothes in a closed room is one of the fastest ways to spike indoor humidity in winter.
• Use a moisture absorber (물먹는 하마-style silica packs are sold at every Korean mart) in closets and corners that don't get airflow.

What's actually included in SharedHomies rent for gas and heating?

Your rent bundles all utilities — gas, electricity, water, and unlimited fiber Wi-Fi — with no separate activation deposit and no setup in Korean required. Specifically, the first ₩75,000 a month of your unit's combined gas + electricity bill is covered by SharedHomies; anything above that ₩75,000 threshold gets split equally between the housemates sharing that unit. That threshold applies to gas and electricity together, not gas alone — the data above is gas-only, so the actual month you'd see an overage depends on the electric bill too, which is why Steve always posts the real total rather than an estimate.

Most months outside the January–February peak don't cross the threshold at all. During the coldest stretch, some houses do — and when that happens, everyone sees the same bill screenshot, with the same account number, at the same time. If you're comparing that against furnishing a Korean apartment yourself and paying utility activation deposits out of pocket, see our breakdown of the hidden costs of DIY renting in Seoul — winter heating is one line in a much longer list.

Thinking about a Seoul winter?

If you're weighing a direct wolse / 월세 lease against something that bundles utilities before you commit to a Korean winter, our pillar guide to renting in Seoul as a foreigner and our monthly rental cost breakdown cover the rest of the cost-of-living picture, alongside our broader guide to daily life and costs in Seoul. For what's actually included across our houses month to month, see the SharedHomies co-living guide or browse available rooms.