As of today, you can type 1 into the Area tab and see 10,000 m², 107,639 sq ft, and 2.4711 ac light up at the same time. No second tab. No scratchpad math. No Googling "how many square feet in a hectare" for the eleventh time this week.
What actually shipped in v0.3.3
- Hectares (ha) and acres live in the Area tab next to square meters and square feet.
- Sortable rows and a Units menu to hide anything you don't use. Work in metric today, hide sq ft and acres. Your layout is remembered across sessions.
- Smarter number formatting. Fewer decimals on a 40-acre parcel, more precision on a 12 m² powder room. The readout stays human from 5 m² to 50 acres.
Type 120 * 80 into any field and press Enter. Math expressions still work. Useful when you're scoping a plot from dimensions rather than reading a figure off a survey.
A short, slightly unflattering history of the acre
An acre is, historically, the amount of land one ox could plow in one day.
That is not a joke. That is the actual definition. A "furlong" (furrow-long) is the distance the ox could drag a plow before needing a rest, which is 660 feet. The "chain" across is 66 feet. 660 × 66 = 43,560 square feet. One acre.
Why so long and narrow? Because oxen, historically, hate turning around. Every turn was lost productivity. So medieval English farmers optimized for long straight lines and minimal ox-pivots, and here we are, 900 years later, still using a unit defined by the attention span of a tired farm animal.
The US makes this modestly worse. There are technically two acres:
- The international acre: 4046.8564224 m² exactly.
- The US survey acre: 4046.872609874252 m².
They differ by about two parts per million. This matters for nobody except surveyors doing very large parcels and people who write blog posts about unit conversions. Arch Convert uses the international acre. If you're a surveyor doing Public Land Survey work in the US, you already know why you need something else.
The hectare is what happens when you let engineers redesign a farm
A hectare is a square 100 meters on each side. 10,000 m². That's it. No oxen involved.
It was introduced in France in 1795 as part of the metric system, and like most things the metric system did, it is offensively reasonable. 100 hectares to a square kilometer. 1 hectare = 10,000 m². Every conversion is just moving a decimal.
A hectare is roughly:
- The area of an international rugby field (with a bit of shoulder).
- 2.47 acres, which is the only awkward number in the whole system, and it's awkward because of the ox, not the hectare.
- About 1.4 soccer pitches, depending on which soccer pitch you pick, because soccer pitches are also not a fixed size, which is another blog post entirely.
When you'll actually reach for each
You'll use acres when you're:
- Pricing rural land in North America, where listings, farm records, and county maps are all in acres.
- Reading any US parcel map.
- Sizing a lot against residential zoning in imperial jurisdictions.
You'll use hectares when you're:
- Doing site planning or masterplanning pretty much anywhere outside the US.
- Reading agricultural data, forestry data, or environmental reports.
- Scoping land use for any European, Australian, NZ, or Canadian (officially) project.
You'll use both, at the same time, if you're:
- An architect on a Canadian project where the site was surveyed in acres but you're designing in metric. Which is most Canadian projects.
- A land planner comparing a rural parcel (acres) to an urban comp (square meters or square feet).
- Anyone explaining to an international client what "40 acres" means when they've never seen an acre in their life.
A couple of numbers worth memorizing
- 1 hectare = 10,000 m² = 2.4711 acres
- 1 acre = 4046.86 m² = 0.4047 hectares = 43,560 sq ft
- 1 square kilometer = 100 hectares ≈ 247 acres
If you forget everything else, remember that a hectare is about two and a half acres. It'll get you 95% of the way there in conversation, and Arch Convert will handle the last 5% of the decimal places.
Try It
Arch Convert now handles hectares and acres alongside square meters and square feet in the Area tab. Drag the rows to reorder, hide units you don't use, and your layout sticks across sessions.
No signup, no ads, no tracking beyond basic analytics. Built for architects, and hopefully slightly less annoying the next time a site plan lands in a unit you weren't expecting.
FAQ
How many acres is one hectare?
2.4711 acres. A hectare is about two and a half acres. If you need the exact number down to the last decimal, Arch Convert will give it to you live as you type.
Why is an acre such a weird number of square feet?
Because it was originally defined as a strip of land 660 feet long by 66 feet wide, which is how far an ox could plow before it needed a break. 660 × 66 = 43,560 square feet. Blame the ox.
Is the US acre the same as the international acre?
Almost. The US survey acre is about 0.0004% larger than the international acre. For any practical design or real estate work, they're identical. For legal surveys of very large parcels in the US, check which one your jurisdiction uses.
What's a "section" of land?
A section is 640 acres, which is one square mile. You'll see this in the US Public Land Survey System, especially for agricultural and rural parcels. Arch Convert doesn't have a section unit yet, but if you need one, multiply acres by 640 or divide by 640.
Can I type math into the Area tab?
Yes. Type 120 * 80 and press Enter to get 9,600 m² with all four units live. Works in every input field across Length, Area, and Volume.
If you work with land area regularly and there's a unit or workflow Arch Convert is still missing, reach out to discuss.