Bunting is one of those decorations that looks effortless once it's up, which is exactly why so many people order the wrong length. A strand that seems generous in the packet can fall short across a doorway, while a table runner bought "by the metre" can end up with flags bunched so tightly they look like a stack of cards. The difference comes down to three measurements: flag width, the gap between flags, and how deeply you let the strand dip between fixing points.

Get those three numbers right and ordering becomes simple arithmetic. This guide walks through the maths for the situations that come up most often: tables, doorways, and tents or marquees.

Start with flag width, not strand length

Most fabric bunting is sold with flags of a standard size, and the two you'll meet most often are roughly 15 cm (6 in) and 20 cm (8 in) wide at the top edge. The width matters more than the length because it sets the rhythm of the whole strand.

Manufacturers usually describe coverage in terms of flags per metre or per foot. A common arrangement is a flag every 10–12 cm along the tape, which works out at roughly 8–10 flags per metre, or about 2.5–3 flags per foot. Lighter, sparser strands run at 6–7 flags per metre; dense, close-packed strands can hit 12 or more.

Here's the useful rule of thumb: a strand covers roughly the same distance as its own length when hung taut, and noticeably less when you let it dip. That single sentence prevents most ordering mistakes.

Flags per foot at a glance

• 6 cm flags, close spacing: about 5 flags per foot – very dense, best for small spaces and cake tables
• 10 cm flags, standard spacing: about 3 flags per foot – the everyday default
• 15 cm flags, standard spacing: about 2 flags per foot – classic garden party look
• 20 cm flags, wide spacing: about 1.5 flags per foot – bold, breezy, good for large tents

Check the product description before you calculate. If it gives a total flag count and a total length, divide one by the other and you'll know exactly what you're buying.

How swag depth changes your coverage

Bunting almost never hangs in a straight line, and that's the point. A gentle dip – the swag – is what makes it look celebratory rather than like a washing line. But every dip eats length.

Picture a 3 m span. Hung taut, a 3 m strand just covers it. Let it drop 30 cm in the middle and you'll need closer to 3.4 m. A deeper, more dramatic 60 cm dip can push the requirement past 4 m. As a rough working rule for moderate swags, add 15–25% to the span; for deep, swooping swags, add 30–40%.

Working out how many swags you want

Rather than one long dip, most installations look best as a series of even swags between fixing points. Decide the swag width first, then count:

1. Measure the total span you need to cover.
2. Choose a swag width – around 60–90 cm looks tidy indoors, 1–1.5 m suits tents and gardens.
3. Divide the span by the swag width to get the number of dips.
4. Multiply the number of dips by roughly 1.2–1.3 to allow for the extra length each dip consumes.
5. Round up, and add one extra flag's worth as a buffer for ties and knots.

So a 6 m run with 1 m swags gives six dips. Six multiplied by 1.25 is 7.5 m of bunting. Order 8 m and you'll have room to adjust on the day.

Bunting for tables

Table bunting has different priorities from overhead bunting. It sits close to the eye, so it needs to look neat, and it often needs to stay put.

For a runner-style strand laid along the front edge or centre of a table, measure the table length and add about 20–30 cm at each end if you want the bunting to hang past the corners. For a rectangular table 1.8 m long, that means roughly 2.2–2.4 m of bunting.

If you're swagging bunting between the front legs of a table, treat it like a mini installation: measure leg-to-leg, then add 20% for the dip. Two swags across a 1.5 m gap need about 1.8 m.

Table tips

• Smaller flags – 6–10 cm – suit table work far better than large ones.
• Keep swags shallow. A 15–20 cm dip is plenty over a table.
• For a cake or buffet table, a single taut strand along the front edge looks cleaner than a swagged one.
• Remember the back of the table too if guests will walk around it.

Bunting for doorways

Doorways are the most common place people run short, because they measure the width and forget the height.

A single strand straight across the top of a door frame only needs the frame width plus a little for tying – about 20 cm extra in total. That's the simplest option and it works well for standard interior doors of around 75–85 cm.

If you want bunting to drape down one or both sides of the doorway, add the drop length. Two 60 cm drops on a 90 cm door means 90 + 60 + 60 + 20 cm of tying allowance, so roughly 2.3 m. That's before any swag, so add 20% if you want a dip.

For an outdoor doorway or a porch, double-check the fixing points. Brick, uPVC, and painted timber all need different hooks, and the bunting should sit high enough that tall guests don't walk into it. A sensible clearance is at least 2 m from the ground.

Bunting for tents and marquees

Tents are the opposite problem: the spans are long and the fixing points are few. This is where flag size really counts, because small flags vanish against a large canvas ceiling.

Go for flags of 15–20 cm on tent runs, spaced about 20 cm apart, and plan swags of 1–1.5 m. Longer swags mean fewer fixing points and a more relaxed, breezy feel; shorter swags look more formal and structured.

A practical approach is to measure from pole to pole and divide into equal swags. If the ceiling run is 10 m and you want 1.25 m swags, that's eight swags. Eight multiplied by 1.3 gives 10.4 m of bunting – order 11 m to be safe, especially if you'll be working at height where adjustments are awkward.

Two details that matter in tents: use cord or zip ties rather than relying on the bunting tape alone, and check that any fixings won't damage the structure. If you're hiring the marquee, ask the supplier what they permit before you start attaching anything.

A quick ordering checklist

Before you buy, run through this:

• Measure the actual span, not the space you think it is.
• Note the flag width and spacing from the product listing.
• Decide taut, shallow swag, or deep swag – and add 15–40% accordingly.
• Count the fixing points and swag evenly between them.
• Add 10% extra, then round up to the nearest whole metre.
• If two lengths are close in price, buy the longer one. You can always coil the surplus at the ends.

Bunting is forgiving once it's up, but it's not forgiving when it's short. Five minutes with a tape measure and a rough calculation will save you a return postage bill and a last-minute scramble on the morning of the party.

Photo: ThomasWolter / Pixabay