Scored with our own care data, a peace lily does best between 400 and 4,000 lux. That puts the north sill at 3,640 lux and everything a couple of metres inside an east or north window at 100 out of 100. The spot the advice usually names, a few feet from a sunny window, reads 10,000 lux a metre from south-facing glass and scores 46. The sill itself, at 13,000, scores 43.
The peace lily is the plant that gets two contradictory instructions on the same label: bright indirect light for flowers, tolerates low light for the rest. Both are true. They are true of different spots in the same room, and a number is the only way to tell which spot you are holding.
Not the best fit right now
The plant's fine, this spot just isn't a match.
Too bright here
Comfortable temperature
Humidity suits it
Airflow suits it
Light is a deal-breaker here. The other three cannot make up for it.
How many lux does a peace lily need?
Before our own scoring says anything: we gathered every published figure we could find for a peace lily. 6 of them, from 5 separate sources, in 3 different units. They are reproduced below exactly as each source writes them, and nothing here is converted.
| Who publishes it | What it says a peace lily needs | What the figure is |
|---|---|---|
| theplantrunner.com | 800–2,000+ lux | Standard foliage plants (pothos, Philodendron, Monstera deliciosa …) — a general band, not a single-species figure |
| houseplantjournal.com | 100 foot-candles | Peace Lily — minimum indirect light |
| houseplantjournal.com | 200 foot-candles | Peace Lily — good indirect light |
| growlightmeter.com | 5 – 10 PPFD / DLI | Peace Lily |
| extension.arizona.edu | 75–150 foot-candles | listed under the heading "Medium Light (75–150 fc)" |
| houseplantsnook.com | 50–100 foot-candles | chart fc level |
In our care data a peace lily sits in the low-light category, and in scoring it comes out ideal from roughly 400 lux up to around 4,000 lux, a slightly lower ceiling than the pothos in the same band. Below the band it holds and does not flower. Above it the flag comes from the bright side, and that is the flag most peace lilies in sunny rooms are wearing.
Nine spots, scored
These are all indoor spots at typical clear-day conditions, with temperature, humidity and airflow set to the plant’s own preferences so that the only thing changing between rows is light.
Every row, one plant each (9)
| Spot | Estimated light | What the light is doing | Verdict |
|---|---|---|---|
| South sill, against the glass | 13,000 lux | Too bright here | Not the best fit right now, 43/100 |
| West sill | 7,800 lux | A bit bright, but workable | Worth a try, 64/100 |
| East sill | 6,500 lux | A bit bright, but workable | Worth a try, 66/100 |
| 1 m in from an east window | 5,000 lux | A bit bright, but workable | Worth a try, 68/100 |
| 3 m in from an east window | 1,984 lux | Just the right amount of light | Great fit, 100/100 |
| North sill | 3,640 lux | Just the right amount of light | Great fit, 100/100 |
| 2 m in from a north window | 1,764 lux | Just the right amount of light | Great fit, 100/100 |
| 3 m in from a north window | 1,111 lux | Just the right amount of light | Great fit, 100/100 |
| A corner 4 m from any window | 125 lux | A little dim, but workable | Worth a try, 63/100 |
Four rows are flagged for too much light and they are the four brightest spots in the house: the south sill at 43, the west sill at 64, the east sill at 66, and a metre in from the east window at 68. That last row is the one to notice. On the pothos table a metre from an east window scores 99. For the peace lily the same 5,000 lux is a shade too much, and the plant does not clear the bar until two metres further in, at 1,984 lux.
The perfect rows are the ones the advice calls second best. The north sill at 3,640 lux scores 100, and it keeps scoring 100 all the way to three metres inside that window at 1,111 lux. The corner four metres from any glass, at 125 lux, is worth a try at 63. That is where a peace lily lives without flowering.
Walking it back from a south window
Most of the peace lilies people ask about are in rooms with a sunny window, so here is that window, followed all the way in.
| Distance from the window | Estimated light | Verdict |
|---|---|---|
| 0.3 m, against the glass | 13,000 lux | Not the best fit right now, 43/100 |
| 1 m back | 10,000 lux | Not the best fit right now, 46/100 |
| 2 m back | 6,300 lux | Worth a try, 66/100 |
| 3 m back | 3,969 lux | Great fit, 99/100 |
| 4 m back | 2,500 lux | Great fit, 100/100 |
| 5 m back | 1,575 lux | Great fit, 100/100 |
The line falls between two and three metres, and it falls hard. At the glass and a metre back the plant is refused, at 43 and 46. Two metres back, at 6,300 lux, it is worth a try at 66. Three metres back, at 3,969 lux, it is 99, and four and five metres are 100. The whole back half of a sunny room is a good spot for a peace lily. The front metre is the part that scorches it, and the front metre is where the light-hungry advice puts it.
The south-window page and the west-window page follow one window each with the temperature and humidity of a real room rather than the plant’s own preferences, which is why their numbers are a few points lower at every distance.
The humidity question comes second
A peace lily is a humidity plant, and every care guide says so. What the guides do not say is that humidity only starts to count once the light is right. In our scoring, moving the humidity at a spot the light has already refused changes the score by a few points, because the light has already decided the verdict. Move the same humidity range at a spot three metres in, where the light is right, and the humidity becomes the whole difference between a plant that is worth a try and one that is a great fit. The west-window page prints that humidity table at the three-metre spot.
So the order is fixed. Find the spot where the light lands inside 400 to 4,000 lux first. Then, and only then, worry about the tray of pebbles.
What do 400 and 4,000 lux look like in a real room?
Numbers like 400 and 4,000 mean very little until you have stood somewhere and know what they feel like, which is the problem, because they do not feel like anything. So here are six places in one ordinary living room, read on a clear day:
| Spot | Reading |
|---|---|
| At the bright window | 20,000 lux |
| 1 m from the window | 15,000 lux |
| 2–3 m away, in window shade | 3,500 lux |
| Middle of the room | 570 lux |
| Darker side of the room | 119 lux |
| The dark corner | 18 lux |
Line that up against the tables. The window at 20,000 lux and the spot a metre from it at 15,000 are both past the peace lily band by more than the south sill in the table. The spot two to three metres in, at 3,500 lux in window shade, is inside the band and close to its top: that is the flowering spot in this room. The middle at 570 lux is inside the band too. The darker side at 119 lux is the corner row, holding. The 3,500 and the 119 both come from the same measured room.
Why the published numbers disagree with each other
Search this and you will find the peace lily filed under medium light by one extension service, under low light by a chart, and under a general foliage band starting at 800 lux by a third source. Our own scoring calls 400 lux ideal and 5,000 flagged, which overlaps all three filings and agrees with none of them about where the edges are.
Both ends can be defended, because a floor and a comfortable band are different questions. None of them can tell you whether your shelf clears the bar, and that is the only question that changes what you do next. The same table built for a snake plant shares the band and comes out kinder at the glass, and the one built for a fiddle leaf fig is close to the mirror image: the four spots that flag the peace lily are the only spots that come near passing the fig.
Published advice is written in tiers while a room is written in numbers; the four tiers with a box to type your own reading into is the general version of this page.
Are peace lilies safe for cats?
The peace lily is listed by the ASPCA as toxic to cats and dogs, because of the insoluble calcium oxalates in every part of the plant. A chewed leaf usually means a sore mouth and drooling rather than anything dangerous, and it is still worth knowing before the pot goes on a low table in a house with a chewer. This is the one fact on this page that does not depend on your spot at all.
By GrowSpot · Published September 12, 2026
