Pounds, Fahrenheit & Gallons: A Practical Guide to US Units for Korean Immigrants

If you've recently moved to the United States from Korea, you've almost certainly run into this scenario: you're at the grocery store trying to buy pork belly, and the price tag says "per lb." You check the weather app before heading out and see "87°F." You pull up to a gas pump and have no idea whether the price per gallon is a good deal or not. The U.S. is one of only three countries in the world — along with Myanmar and Liberia — that doesn't use the metric system as its everyday standard. Instead, it uses what's officially called US Customary Units. Don't confuse these with the British Imperial system: while the names overlap, some units (like the gallon) are actually different sizes. If you're cooking from a British recipe, watch out for that. The bottom line is that no amount of memorizing conversion formulas will make you truly comfortable — what you need is intuition.

This guide goes beyond listing formulas. It covers how each unit actually shows up at the grocery store, gas station, doctor's office, and real estate listing — plus the mental shortcuts that let you make quick calls without reaching for your phone, and the mistakes Korean Americans most commonly make along the way.

Weight: Pounds and Ounces — You'll Use These Every Single Day

One pound (lb) is roughly 453 grams; one ounce (oz) is about 28 grams. Meat, produce, and seafood at any grocery store — whether it's H Mart, Kroger, Safeway, or Costco — are priced by the pound. The mental shortcut that actually sticks: 1 lb ≈ 450 g, and 2 lbs ≈ 900 g, which is basically 1 kg. Flip it around: if a recipe calls for 1 kg of something, buy about 2.2 lbs. Packaged products are required by federal law to show both US and metric weights (e.g., "16 OZ (454 g)"), so you can always find the gram figure on the label for a direct comparison with Korean products.

At the doctor's office, you'll be asked your weight in pounds. Know your number ahead of time: multiply your weight in kilograms by 2.2. If you weigh 65 kg, that's about 143 lbs. Baby weights are expressed in a mixed format like "7 lbs 4 oz." Prescription labels and nutrition facts panels also use ounces, so it's worth getting comfortable with the unit early.

• Common mistake #1: Ordering "one pound" of meat at the deli counter and being surprised by how little you get. In Korea, most people buy meat in 600 g–1 kg portions. For a family of four, plan on at least 2–3 lbs for bulgogi or steak.
• Common mistake #2: Confusing weight ounces (oz) with fluid ounces (fl oz). These are completely different units — one measures mass, the other measures volume. More on fl oz in the next section.

Temperature: Fahrenheit — Weather, Cooking, and Fevers All Work Differently

The exact formula is °C = (°F − 32) × 5/9, but running that math in your head every morning is impractical. Instead, anchor yourself to a handful of reference points:

• 32°F = 0°C — freezing; ice on the road
• 50°F = 10°C — chilly fall day; grab a jacket
• 68°F = 20°C — comfortable spring weather
• 86°F = 30°C — hot summer day; shorts and a t-shirt
• 100°F = 37.8°C — heat advisory territory; also close to human body temperature

For a quick estimate, try this shortcut: subtract 30 from the Fahrenheit reading, then divide by 2. So 90°F → (90 − 30) ÷ 2 = 30°C. It's not perfectly accurate, but it's close enough to decide what to wear. For body temperature, U.S. schools and clinics use Fahrenheit: normal is 98.6°F (37°C), and a fever is generally defined as 100.4°F (38°C) or above. If your child's school asks for a fever policy acknowledgment, make sure you know the Fahrenheit threshold. Oven temperatures in American recipes are also in Fahrenheit — two conversions worth memorizing: 180°C ≈ 350°F and 200°C ≈ 400°F.

Volume: Gallons, Quarts, and Cups — Gas, Groceries, and Cooking

The U.S. volume hierarchy runs: gallon → quart → pint → cup → fluid ounce (fl oz). The one number worth anchoring to: 1 gallon ≈ 3.785 liters. Gas prices at the pump are always quoted per gallon. As of 2026, prices vary significantly by state and fuel grade — California consistently ranks among the highest in the country, while Texas tends to be much lower — so rather than comparing sticker prices, convert to a per-liter figure to get a meaningful comparison with Korean fuel costs: divide the per-gallon price by 3.785.

At the grocery store, milk and juice come in gallons (1 gal), half-gallons (≈ 1.89 L), and quarts (1 qt ≈ 946 mL). If you're used to buying 1-liter cartons in Korea, a quart is your closest equivalent. In recipes, you'll constantly see cups (1 cup ≈ 240 mL), tablespoons (1 tbsp ≈ 15 mL), and teaspoons (1 tsp ≈ 5 mL). A basic set of measuring cups and spoons — available at Target or Amazon for around $5–$15 — makes cooking from American recipes much less frustrating.

Length and Distance: Inches, Feet, and Miles — Driving, Shopping, and Real Estate

The length system goes: inch → foot (ft) → yard → mile. Key conversions: 1 inch ≈ 2.54 cm; 1 foot = 12 inches ≈ 30 cm; 1 mile ≈ 1.6 km. Speed limit signs are in mph (miles per hour). A school zone at 25 mph is about 40 km/h; a freeway at 65 mph is about 105 km/h. If you're used to driving in Korea, recalibrating your speed instincts to mph takes a conscious effort — otherwise you risk either speeding or driving frustratingly slow.

Real estate listings show home size in square feet (sq ft). To convert: sq ft ÷ 10.764 = square meters, then ÷ 3.3 = pyeong (Korean unit). A 1,000 sq ft apartment is roughly 93 m², or about 28 pyeong. For clothing, U.S. shoe sizes differ from Korean mm-based sizing: Korean women's 240 mm is roughly US 7–7.5, and men's 270 mm is roughly US 9–9.5, though this varies by brand. Always try before you buy, or confirm the return policy first.

Building Intuition — and Using Your Phone When You Need To

The fastest conversion tool you already have: just type "72 fahrenheit to celsius" or "2 pounds to kg" directly into Google's search bar. No app needed — the answer appears instantly. On iPhone (iOS 18 and later), the built-in Calculator app includes a unit conversion mode. Samsung's Calculator app has had a built-in converter for a while. You can also just ask Siri or Google Assistant out loud.

That said, the real goal is to stop needing to convert at all. Three habits that speed up the process: ① Set your weather app to Fahrenheit only — turn off the Celsius display — and just live with it. ② At the grocery store, try to read pound prices directly instead of mentally converting. ③ Watch only the mph readout on your speedometer. The first couple of weeks feel awkward, but the units you see every day become intuitive faster than you'd expect.

• Common mistake #3: Using a Korean recipe or Korean appliance manual — with Celsius temperatures and gram measurements — directly with a U.S. oven or measuring cups. American ovens are calibrated in Fahrenheit, and American recipes measure by volume (cups, tablespoons). Always convert before you cook.

Units come up most often at the grocery store, behind the wheel, and at the doctor's office. For tips on comparing unit prices and saving money at American supermarkets, see our U.S. Grocery Shopping Guide. For mph speed limits and getting your driver's license, check out the U.S. Driver's License Guide. For navigating the U.S. healthcare system, read ER vs. Urgent Care vs. Clinic — Which One Do You Need?

Frequently Asked Questions

Q: Do Korean grocery stores use Korean units?
No — H Mart, Galleria, and Hanahreum all operate under U.S. law, so official pricing is in pounds. That said, packaged products typically show gram weights alongside ounces, and staff can often explain quantities in Korean if you ask. It's still worth getting comfortable with pound-based pricing since that's what the register rings up.

Q: What if I don't know my height and weight in U.S. units when the doctor asks?
Most clinics measure you again at check-in anyway. If you're caught off guard, just say: "I'm not sure in pounds and feet — could you measure me?" That said, it's handy to have your numbers ready. For weight: kg × 2.2 = lbs. For height: divide your height in cm by 2.54 to get total inches, then divide by 12 for feet (the remainder is inches). Example: 170 cm ÷ 2.54 ≈ 67 inches = 5 feet 7 inches.

Q: Is there a unit converter app you'd recommend?
Honestly, Google search is faster than any dedicated app. If you prefer a standalone app, search "unit converter" in the App Store or Google Play and pick a free one with strong reviews. More importantly, try not to become app-dependent — having five or six key reference points memorized will serve you far better in real-life situations where you need to make a quick call.

Note: All figures in this article reflect standard conversion values and general U.S. averages as of 2026. Actual prices, sizes, and measurements vary by region, brand, and product. For medical or legal decisions, always consult a qualified professional.