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Shop BySet the old version of this calculator to a 25cm opening and carnations, and it told you to buy 541 stems. Nobody rang about it. I take that as nobody with a bowl that wide ever got to the bottom of the page, which is not the same thing as the tool being right.
The maths was an area sum with nothing stopping it. Opening divided by stem, multiplied out, no ceiling anywhere. It was calibrated at about 10cm and it fell over on both sides of that. Three lilies into a 3cm bud vase, which is two lilies too many. Five hundred and forty one carnations into a bowl. And the Lush figure was Classic multiplied by 1.5, which is not a thing that can physically happen. The hole does not get wider because you want more flowers in it.
So Anna and I pulled it apart at Farm & Co in Cudgen, over two flat whites and a napkin, same as the first one. She did the stem measurements. I did the geometry. This version has a ceiling on it, understands what a vase height means for stem length, and will run the sum backwards if you have already got the flowers and no idea what to put them in.
The tool is below. Everything under it is the working.
The Perfect Fit
Built from measured stem footprints, not guesswork
Quick match · no ruler needed
Not sure how wide yours is? Lay a bank card across the opening. A card is 8.6cm long, so half a card is roughly 4cm.
Vase shape
Flower type
10 cm
25 cm
12 stems
50 cm
Most bought bunches run 45cm to 60cm before you trim them.
What fits, and what it looks like
7
Minimal
airy
10
Classic
what we aim for
13
Lush
at capacity
Cut your stems to 38 to 44 cm. Measured from the cut end to the base of the bloom.
Add two or three stems of foliage on top of any of these counts. It fills without adding flower cost.
Once you know the number: flower bunches, roses, lilies or natives.
The vase you want
10.9 cm
Across the opening. Anything from 9.8cm for a packed look out to 13.4cm for an airy one.
About 31cm tall, which puts roughly two thirds of the flower above the rim.
If the only vase you own is wider than that, put the flowers in and add foliage until the opening is full.
Not arranging it yourself? Try florist's choice and let the florist pick stems that suit the vessel.
5.3
square cm of opening one rose actually takes
10
roses in a standard 10cm florist cylinder
1.6x
vase height to cut stem length
Part One
The Opening Is The Only Measurement That Counts
Height does not constrain you, and neither does volume, or how good it looks sitting empty on a shelf. The opening constrains you. A 45cm cylinder and a 14cm cylinder with the same mouth hold the same number of roses. One just looks more impressive doing it.
The old tool asked for the opening and then punished you twice for the same fact. Measure a 5cm neck, and it gave you the count for a 5cm neck, then knocked another 30 per cent off for being a narrow-neck vase. The narrowness was already in the number you typed. So shape does a different job now. It sets how densely you should fill the opening you measured, and how far above the rim the flowers can sit before the whole thing stops looking deliberate.
Anna, qualified florist
People measure the widest part of the vase. That is the part that does not matter. Water sits in the belly. The stems are held at the throat, and the throat is what decides your number. A necked vase grips the stems where they cross so they hold whatever angle you put them at. Six stems in a good bottle vase look arranged. Six stems in a straight cylinder look like six stems in a straight cylinder, because nothing is holding them apart and they all slump to one side inside an hour.
Flared bowls have the opposite problem. Nothing grips, so every stem leans outward against the rim and you end up with a ring of flowers around a gap in the middle. The calculator asks for more stems in a flared vase for that reason, not because the maths says so.
Part Two
A Hydrangea Is Not A Rose With A Different Head On It
Every stem takes up more room than the stem. There is the woody bit you cut, then the leaf nodes sitting around it, then the gap the next stem needs so it can hold its own angle instead of yours. Florists call the total the footprint. It is the number that actually goes into the sum.
Anna on stem width
Measure a rose at the cut and you get 8 to 10 millimetres. By the time the leaf nodes and the air around it are in, it is occupying about two and a half centimetres of the opening, so call it five and a bit square centimetres each. An oriental lily is 12 to 15 millimetres at the cut and closer to four centimetres in the vase, because the foliage runs the full length of the stem and it will not compress. Four lilies and ten roses fill the same hole. Nobody believes that until they do it on a bench.
Back in the Kingscliff shop a customer ordered a dozen mixed natives for her mum in Tweed Heads, and rang back upset that the arrangement looked small next to the dozen roses she had sent the year before. Same dozen stems. Banksia and protea heads are three times the width of a rose at the neck, so a dozen of them read as a fistful rather than a bunch. We added foliage at our cost, because we had not explained it up front.
Here is what a stem is actually worth in vase real estate. The last column matches what the calculator will tell you for a straight 10cm opening at Classic density, because it is the same sum.
| Flower | Stem at the cut | Footprint in the opening | Classic count, 10cm opening |
|---|---|---|---|
| Carnation | 4 to 5mm | 2.8 sq cm | 19 stems |
| Freesia | 3 to 5mm | 2.8 sq cm | 19 stems |
| Rose | 8 to 10mm | 5.3 sq cm | 10 stems |
| Tulip | 8 to 10mm | 5.3 sq cm | 10 stems |
| Gerbera | 7 to 9mm | 5.3 sq cm | 10 stems |
| Oriental lily | 12 to 15mm | 12.6 sq cm | 4 stems |
| Hydrangea | 12 to 15mm | 12.6 sq cm | 4 stems |
| Banksia or protea | 12 to 18mm | 12.6 sq cm | 4 stems |
A dozen roses in a 10cm cylinder lands just above Classic. Full, not packed. Which is about where a dozen has always looked right, and now there is a number under it.
A vase is a hole with a bucket attached. The hole is the only part that limits you.Anna, Qualified Florist, 15+ Years
Part Three
Height Is Where Most Of It Actually Goes Wrong
A fair share of the "it looks empty" calls we take are not about the count at all. The number of stems is fine. They are sitting too low, or standing up like a hedge, and either way the eye reads it as not enough. Three things fix it and none of them cost anything.
1
Measure the vase, not the flowers
Base to rim, in centimetres. It drives everything that follows, and it is the measurement people skip because it feels like it should not matter. Put it into the calculator above and you get the cut length back.
2
Cut to about 1.6 times the vase height
A 25cm vase wants stems around 38cm to 44cm, cut end to the base of the bloom. Roughly two thirds of the flower then sits above the rim, which is the proportion that reads as arranged rather than dumped. Necked vases carry more, up to double the vase height, because the throat holds the stems steady. Wide bowls carry less, closer to 1.3 times, or the vase tips forward under its own arrangement. Cut long first. You can always take another two centimetres off, and you cannot put them back.
3
Strip anything that will end up under water
This is the one that decides whether you get four days or nine.
Anna
Leaves below the waterline start breaking down inside two days. The water goes cloudy, then it goes sour, and the bacteria colonise the cut ends so the stems stop drinking while they are standing in a full vase. Strip every leaf that will be wet. Every one. Then change the water on the third day whether it looks like it needs it or not, and re-cut a centimetre off the bottom while you are there. I have watched hundred-and-fifty dollar arrangements die on day four for no other reason than three leaves nobody bothered to pull off.
Part Four
Minimal, Classic, Lush, And Why Lush Used To Be A Lie
Capacity is the number of stems that physically pass through the opening with each one holding its own angle. Call that 100 per cent. Nothing sensible happens above about 85, because at that point the stems are propping each other upright and any bloom that wants to open has nowhere to open into. So Lush is 85 per cent of capacity. It is not a bigger number bolted on top of Classic. It is the ceiling.
| Look | Share of capacity | What it reads as | Where it works |
|---|---|---|---|
| Minimal | 45% | Deliberate gaps. Every stem visible on its own. | Bud vases, single-variety stems, hospital bedsides where space is tight. |
| Classic | 68% | Full, with room for every head to open. | Almost everything. This is what our partner florists build to. |
| Lush | 85% | Packed. The blooms touch and hold each other up. | Anniversaries, big birthdays, a dining table people will sit around. |
Those percentages shift with the shape. A necked vase drops Classic to 60 per cent, because the flare above the throat does some of the visual work for you. A flared bowl lifts it to 78, because a wide rim lets every stem drift outward and the extra bulk is what keeps the middle from emptying out.
The old version set Classic at full capacity and then offered Lush at one and a half times capacity. So the most-recommended number was already the physical maximum, and the premium option did not exist. It sat there doing that for a year and I did not check it. That is the bit that annoys me, not the maths.
Part Five
What The Calculator Will Not Do For You
It counts flowers. It has no idea about foliage, and foliage is doing more work in a good arrangement than most people give it credit for.
Anna on greenery
Three stems of eucalyptus will do more for eight roses than four more roses will. Greenery sits between the heads and holds them apart, so each bloom gets its own space instead of squashing into the one beside it. It also fills low, down near the rim, which is exactly where a thin vase reads as thin. Buy the foliage. It is the cheapest thing on the bench and it is the difference between eight roses and eight roses that look like twelve.
The other thing it cannot do is hold your flowers upright in a wide vessel. Past about an 18cm opening the count stops meaning much, because there is nothing for the stems to lean on and they all migrate to the edge.
The tape grid, for anything wider than 18cm
Run strips of clear tape across the mouth of the vase in both directions to make squares about 2cm across. Put the foliage in first, one stem per square around the outside, then the flowers into the middle squares. Everything stays where you put it and the tape disappears under the greenery. Without a grid, a wide bowl gives you a ring of flowers around a hole, no matter how many stems you buy.
And if you are ordering instead of arranging, none of this is your problem. Our partner florists build to the container in front of them, which is a luxury a calculator does not have. Anna's line on that has not changed in fifteen years: the person holding the stems can see the vase, and no sum beats looking at it.
A note from the other half
If Yours Looks Thin, Blame The Vase First
Siobhan Thomson, Co-Founder
I am the wrong person to be writing anything on this page, because I am the one in our house who puts a bunch straight into whatever is closest, usually the jug, and then stands back wondering why it looks like it is lying down. Andrew measures things. I do not, and I am not going to start now.
But the thing people ring us about is almost never the flowers. It is the gap between what they pictured and what turned up on somebody's kitchen bench, and a lot of that gap is the vase doing something nobody expected it to do. So if the bunch that arrived looks thin, try a smaller vessel before you decide we sent a small bunch. Nine times out of ten it is the vase. The tenth time, ring us on 1300 360 469 and we will sort it out, and I would much rather have that call than read about it three weeks later.
Further Reading
Getting the count right is the first half. Keeping them alive once they are in the water is the other, and Anna has written most of that down already.
What To Do Each Morning To Keep Flowers Fresh The five-minute routine that adds days to a vase, from someone who did it professionally for fifteen years. Basic Flower Care 101 Cutting angles, water temperature, which flowers hate each other, and what the sachet actually does.
If you would rather someone else did the sum, that is more or less our whole business. A florist in or near the delivery suburb builds it to the container they have in front of them, then it goes out that day.
See what we send
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Questions? Ring 1300 360 469, 7am to 6pm weekdays and 10am Saturdays. All Australian, no offshore call centre.
About the Authors
The stem measurements are Anna's. The geometry, and the year of wrong numbers before it, are Andrew's. Read our full story.
Andrew, Ivy, Siobhan and Asha. Hobart, June 2024.
