1.21 Gigaspheres!

[odigity]

It all started with an innocent trip to the Nightwatcher, and ended with my "flesh and garments glowing with golden light in a 10-foot radius".

Well, how bright is that, exactly? Relative to an infused sphere? A candle? An oil lantern? What are the tools and maths of light in Stormlight?

1) The Rules

p.258 — "Equipment > Candle: While lit, the candle sheds light in a 15-foot radius."

p.259 — "Equipment > Lantern (oil): While lit, this lantern sheds light in a 30-foot radius."

p.259 — "Equipment > Lantern (sphere): This lantern includes a locked cage, usually just under 1 foot in diameter, into which infused spheres can be placed to shed light. Depending on how full the lantern is, it sheds a different radius of light: 60 feet when entirely filled with spheres, 30 feet when half full, 15 feet when quarter-filled, and 5 feet when at least 1 mark or broam^1 is within it."

To sum up:

Range  Examples
─────  ────────────────────────
   5'  mark, broam
  10'  my character
  15'  candle,      1/4-full SL
  30'  oil lantern, 1/2-full SL
  60'                   full SL

2) How Big Are Your Balls?

We need two more values — the size of a monetary sphere, and the size of a sphere lantern (which is also spherical).

Experts have estimated a monetary sphere's size at 15-20mm. I will use 20mm here. (Using 15mm makes things worse, as you'll see.) I will also use 10g as the weight of a 20mm glass sphere, calculated by Grok.

The SHB describes a sphere lantern as "just under 1 foot". If it's literally an empty cage packed tightly with 20mm spheres, a 12" lantern would hold ~2100 spheres — which is absurd in terms of both cost and weight (46lbs). Even a 10" lantern holds ~1200 spheres. You can cut that down if we take up most of the space with a ball of wood, leaving just enough room between the ball and the cage for a single layer of spheres. Even then, a 10" lantern still holds several hundred spheres.

Let's try attacking this problem from brightness instead of volume...

3) Back to Reality

According to Grok...

Brightness

• a typical candle = 1 lumen (convenient!)

• oil lanterns = 5-15 lumens

• a 60w incandescent bulb = 800 lumens (for comparison)

Range

The range of useful light from a typical candle is:

• ~0.3–0.5 meters for detailed tasks like reading (10–50 lux)

• ~1–3 meters for basic visibility or navigation (0.1–1 lux)

• beyond ~5 meters, the light is too dim for most practical purposes, though it remains faintly visible

Nice! So far this tracks with the SHB's definition of candle as providing value out to 15 feet. Now, through the magic of the Inverse Square Law (and with Grok doing the math), we can determine that the follow brightnesses are necessary to achieve the equivalent brightness of a candle at 15 feet at our other distances of interest:

 5'   0.11 candles / lumens
10'   0.44 candles / lumens
15'   1    candles / lumens
30'   4    candles / lumens
60'  16    candles / lumens

...and if a sphere sheds light in a 5' range — the same as 0.11 candles / lumens — then 1 candle / lumen = 9 spheres.

4) In Summation

If we throw out the "just under 1 foot" nonsense, we can make the rest work:

Lumens  DSL   HSL          Sph  Rng  Examples
──────  ────  ───────────  ───  ───  ───────────────────────────────────
  0.11     -            -    1   5'  mark, broam
  0.44     -            -    4  10'  my character
  1     1.9"  2.5" (0.9")    9  15'  candle,      1/4-full SL  (0.2 lbs)
  4     2.5"  4.2" (2.6")   36  30'  oil lantern, 1/2-full SL  (0.8 lbs)
 16     5.8"  7.5" (5.9")  144  60'                   full SL  (3.2 lbs)
──────  ────  ───────────  ───  ───  ───────────────────────────────────

DSL = Dense Sphere Lantern

HSL = Hollow Sphere Lantern (wooden core diameter in parens)

Finally... I advise buying a 7.5" sphere lantern with 5.9" suspended wooden core, then start saving your clearmarks until you have a full set of 144.

---

Looking forward to feedback, including corrections. (I'd like to get this right.)

---

Note^1: My group has houseruled that broams produce twice as much light as marks, just as we've houseruled that broams can store twice as much Stormlight, because we value verisimilitude — but that's outside the scope of this thread.

[First of the Tide He/him]

@Ookla the Dokja's gonna get you

also, you are incorrectly assuming that if you replace 1 candle with 9 spheres, then it will produce the same amount of light at all distances, which is... not how light works

also, you are completely ignoring that sphere's don't pack perfectly

[CoderDrag0n8 He/They]

26 minutes ago, First of the Tide said:

@Ookla the Dokja's gonna get you

also, you are incorrectly assuming that if you replace 1 candle with 9 spheres, then it will produce the same amount of light at all distances, which is... not how light works

also, you are completely ignoring that sphere's don't pack perfectly

wait why am i gonna get him?

[First of the Tide He/him]

13 minutes ago, Ookla the Dokja said:

wait why am i gonna get him?

Trauma  VVV

Spoiler

AI

*hisss*

Isn't this you?

On 11/21/2025 at 5:20 PM, CoderDrag0n8 said:

You... You... YOU USE AI????????

*brings out knife*

Argue why i should let you live.

Edited December 10, 2025 by First of the Tide

[CoderDrag0n8 He/They]

55 minutes ago, First of the Tide said:

Trauma  VVV

  Reveal hidden contents

AI

*hisss*

Isn't this you?

On 11/21/2025 at 5:20 PM, CoderDrag0n8 said:

You... You... YOU USE AI????????

*brings out knife*

Argue why i should let you live.

Yeah, i hate AI, but there is no confirmation it is AI generated. (I mean i though it was likely, but ya never know)

[First of the Tide He/him]

4 hours ago, odigity said:

(and with Grok doing the math),

 

4 hours ago, odigity said:

I will also use 10g as the weight of a 20mm glass sphere, calculated by Grok.

 

4 hours ago, odigity said:

According to Grok...

Brightness

• a typical candle = 1 lumen (convenient!)

• oil lanterns = 5-15 lumens

• a 60w incandescent bulb = 800 lumens (for comparison)

 

[CoderDrag0n8 He/They]

8 minutes ago, First of the Tide said:

 

 

 

Oh i see

Grok is an AI isn't it

yep it is, just checked

welp.