🏠 Home & DIY

BTU Calculator (AC Size)

Estimate air-conditioner capacity in BTU/h for a room.

ft²

Results

Recommended capacity
8,000 BTU/h
In tons
0.67
In kW
2.34

📊 BTU Calculator (AC Size) chart

How the recommended capacity changes as the room area varies. The orange dot marks your current value.

What is the BTU Calculator (AC Size)?

Estimate air-conditioner capacity in BTU/h for a room. Order the right amount the first time. These construction and DIY calculators estimate materials for common home projects and include sensible waste allowances.

BTU Calculator (AC Size) – free online home & diy tool illustration
BTU Calculator (AC Size) — free, exact and private.

How to use the BTU Calculator (AC Size)

  1. Enter your room area, your sun exposure, your regular occupants.
  2. Tick the options you need: is a kitchen.
  3. Results update automatically as you type; you can also press Calculate.
  4. Read the output: recommended capacity, in tons, in kw.
  5. Use the 📊 chart to see the result visually, then copy or share it.

Formula and method

BTU ≈ 20 × ft² × sun factor + 600 per extra person + 4,000 for kitchens (ENERGY STAR guideline)

Worked example

With room area = 400 ft², sun exposure = Normal, regular occupants = 2, is a kitchen = no, the BTU Calculator (AC Size) returns recommended capacity: 8,000 BTU/h; in tons: 0.67; in kw: 2.34.

Tips for better results

  • Add 5–15% for waste, cuts and breakage depending on the material.
  • Measure twice and round up when buying — returns are easier than second trips.
  • Coverage figures vary by product, so check the label or spec sheet.

⚠️ Material estimates are approximate. Follow local building codes and manufacturer instructions.

Frequently asked questions

What does the BTU Calculator (AC Size) do?

Estimate air-conditioner capacity in BTU/h for a room.

How is it calculated?

The BTU Calculator (AC Size) uses this method: BTU ≈ 20 × ft² × sun factor + 600 per extra person + 4,000 for kitchens (ENERGY STAR guideline).

Can you show an example?

With room area = 400 ft², sun exposure = Normal, regular occupants = 2, is a kitchen = no, the BTU Calculator (AC Size) returns recommended capacity: 8,000 BTU/h; in tons: 0.67; in kw: 2.34.

Is the BTU Calculator (AC Size) accurate?

It uses standard published formulas and is tested against known values, but results are estimates for guidance. Material estimates are approximate. Follow local building codes and manufacturer instructions.

Is this tool free and private?

Yes — the BTU Calculator (AC Size) is completely free with no sign-up, and it runs entirely in your browser, so the values you enter are never uploaded to our servers.

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