Say your meter reads 300 foot-candles and you want to know whether that counts. The first answer you find says bright indirect light is 500 to 1,000 fc, so you are short. The next says 1,000 to 2,000 fc, so you are nowhere near. A third works in lux and puts the same phrase at roughly 90 to 465 fc, so you are comfortably inside it. All three of those were on the first page of the same Google search on the day this was written.
So here is the full spread, then the conversion, then the part that actually decides whether your plant is happy.
Worth a try
It can work here with a little care.
A little dim, but workable
Comfortable temperature
Humidity suits it
Airflow suits it
What does page one of Google actually say?
These are published bands for the same phrase, read on 2 August 2026 from a signed-out US search. Where a source published lux, the foot-candle column is converted rather than quoted.
| Source | “Bright indirect” in foot-candles |
|---|---|
| Google AI Overview, for this exact question | 500 to 1,000 fc |
| Google AI Overview, for “foot candles chart for plants” | 500 to 1,000 fc, labelled high light |
| How Many Plants | 1,000 to 2,000 fc |
| Thursd (from the results page) | 500 to 1,000 fc |
| Spider Farmer (published as 1,000 to 5,000 lux) | about 90 to 465 fc |
| r/houseplants, top answer (from the results page) | 400 to 800 fc |
| Arkansas Cooperative Extension, high light (from the results page) | 500 to 1,000 fc preferred |
Two things in that table are worth sitting with. The first is that Google’s own AI Overview calls 500 to 1,000 fc bright indirect on one query and high light on another, on the same day. The second is that the two extremes do not overlap at all: everything Spider Farmer calls bright indirect is dimmer than anything How Many Plants calls bright indirect. There is no reading that both would accept.
How do you convert foot-candles to lux?
One foot-candle is one lumen per square foot. One lux is one lumen per square metre. A square metre holds about 10.764 square feet, so the conversion is fixed: 1 fc = 10.764 lux, and multiplying by ten in your head is close enough for a plant.
Which unit you meet depends on where the writing came from. Handheld meters sold in the US and older horticultural tables use foot-candles. Phone apps and most sources outside the US report lux. Neither is more accurate, and a source quoting foot-candles to three digits is not being more precise, it is just using smaller numbers.
We publish in lux across this site, so here is the same room in both.
What do those numbers look like in a real room?
One ordinary living room, one clear day, every reading taken within the same hour at roughly pot height.
| Where in the room | Lux | Foot-candles |
|---|---|---|
| At the window glass | 20,000 | about 1,860 fc |
| One metre in | 15,000 | about 1,390 fc |
| Two to three metres in | 3,500 | about 325 fc |
| Middle of the room | 570 | about 53 fc |
| The darker side | 119 | about 11 fc |
| The corner | 18 | about 2 fc |
Now put that against the table above. The middle of that room reads 53 fc, which sits at or below the bottom of every published low-light band and nowhere near any bright indirect band, and it is the spot most people describe as bright because standing in it genuinely feels bright. The window itself reads about 1,860 fc, which one source on page one would call bright indirect and another would call direct sun. The full six-point measurement is here.
Why do the published numbers disagree?
They are answering different questions. A band built around a plant growing quickly sits higher than one built around a plant staying healthy. Both are legitimate, and neither says which one it is doing.
The phrase describes a quality, not a quantity. “Bright indirect” originally meant plenty of light with no direct beam landing on the leaves. That is a description of the path light takes, not of how much arrives, and a bright north room and a shaded spot beside a south window can both satisfy it at very different intensities.
Where the meter was held changes the answer. Held up at the window facing out, a meter reads the sky. Laid flat where the leaves actually are, it reads what the plant gets, which is often a small fraction of the first number. If you are using a phone, set the phone down at the spot with the screen facing up rather than pointing it anywhere.
Is the same reading the same answer for every plant?
Here is the part the band cannot cover. Take one spot, a metre back from a bright window with no direct sun, the exact thing the phrase is describing. Scored against four common houseplants, with the room held identical for all four at 22 °C, 50% humidity and light airflow, the light dimension alone comes out two different ways.
For a monstera and for a ZZ plant, the light at that spot passes outright. For a croton and for a fiddle leaf fig, it is flagged: workable, but on the dim side of what they want. The overall scores land at 94, 94, 66 and 66, and the two lower ones are lower because of light. Nothing about the spot changed. The reading did not change. The phrase certainly did not change.
That is why a number on its own, in either unit, cannot finish the job. It has to be compared against something, and the something is the plant.
How fast does bright indirect stop being enough?
Same window, same plant, walking backwards. These are estimates for the croton in the card above, at 23 °C and 55% humidity with light airflow, so the only thing changing is distance. In foot-candles the four rows come out at roughly 340, 260, 165 and 105 fc.
| Where the pot sits | Estimated light | Verdict |
|---|---|---|
| Right at the glass (0.3 m) | 3,640 lux | Workable, a little dim (66/100) |
| One metre back (1 m) | 2,800 lux | Workable, a little dim (66/100) |
| Across the room (2 m) | 1,764 lux | Too dim (46/100) |
| Against the far wall (3 m) | 1,111 lux | Too dim (46/100) |
Every row in that table would be called bright indirect light by somebody, because every row is bright ambient daylight with no beam on the leaves. Two of them work for this plant and two do not. The label held all the way down and stopped meaning anything about halfway.
What can a light reading not tell you?
Light is the dimension people measure because it is the one with a gadget attached. It is also only one of four things a spot does to a plant. The same shelf has a temperature, a humidity and an amount of moving air, and a reading of 300 fc says nothing about any of them. A bright kitchen windowsill above a radiator and a bright bedroom windowsill are the same light and different places to live.
So take the reading, by all means. Then check it against the plant you actually own, in the spot you actually meant, rather than against a phrase whose published bands do not even overlap.
About this article
The published bands were read, not recalled. Every row in the first table came from opening that result on 2 August 2026 from a signed-out US search. Where a figure was only on the results page and not confirmed on the source’s own page, it is marked as coming from the results page. The two AI Overview rows are what Google itself returned for those two queries that day, and they may not say the same thing tomorrow.
The six-point room readings were measured, modestly: a phone used as a light meter, laid flat at roughly pot height, same hour for every spot, one clear day, one room, single samples rather than a study. That room’s orientation was never recorded. The foot-candle column is a straight conversion at 10.764 lux per foot-candle, not a second measurement.
The verdicts and the distance table are estimates, produced by the same scoring engine that runs in the GrowSpot app and in the free spot checker on this site. Light was estimated from window direction and distance under typical clear conditions rather than measured in your home. In the four-plant comparison the other three dimensions were held identical for all four rather than tuned per plant, which is why the two higher scores are 94 and not 100: at light airflow those two pick up a minor flag of their own. The gap between 94 and 66 is the light dimension. Care baselines come from our curated care data. Where a figure is an estimate we have said so, and where we do not have a reading we say that rather than filling the gap.
