From f35ca56732e49fa72a3e85b2db2ec5b3f1f674c9 Mon Sep 17 00:00:00 2001
From: Codex <codex@example.com>
Date: Sat, 7 Mar 2026 18:46:01 +0000
Subject: [PATCH] Add 40 light calculators

---
 calculators_list.md                     | 40 +++++++++++++++++++++++++
 hdyc-svelte/src/lib/data/calculators.ts | 40 +++++++++++++++++++++++++
 2 files changed, 80 insertions(+)

diff --git a/calculators_list.md b/calculators_list.md
index f50099e..def9c0f 100644
--- a/calculators_list.md
+++ b/calculators_list.md
@@ -638,6 +638,46 @@ The registry currently contains 416 unique calculator slugs.
 | Long Tons to Pounds – Convert long tons to pounds. | long-tons-to-pounds | 2240 |
 | Long Tons to Short Tons – Convert long tons to short tons. | long-tons-to-short-tons | 1.12 |
 | Lux to Foot-candles – Convert illuminance from lux to foot-candles. | lux-to-foot-candles | 0.09290304 |
+| Candela to Foot-candles – At 1 foot away, one candela yields one foot-candle of illuminance. | candela-to-foot-candles | 1 |
+| Foot-candles to Candela – Convert illuminance in foot-candles into a luminous intensity at 1 foot. | foot-candles-to-candela | 1 |
+| Candela to Lux (1 ft) – One candela at a 1-foot distance produces about 10.7639 lux on the target plane. | candela-to-lux-at-foot | 10.7639 |
+| Lux to Candela (1 ft) – Turn lux measured 1 foot away into the equivalent candela luminous intensity. | lux-to-candela-at-foot | 0.09290304 |
+| Candela to Nits – Treat 1 candela distributed over 1 square meter as 1 nit for comparing luminance. | candela-to-nits | 1 |
+| Nits to Candela – Assume a 1-square-meter patch to convert nits into candela. | nits-to-candela | 1 |
+| Candela to Candlepower – Translate candela intensity into the legacy candlepower scale (1 cd ≈ 1.01937 cp). | candela-to-candlepower | 1.019367 |
+| Candlepower to Candela – Flip historical candlepower values back into modern candelas (1 cp ≈ 0.981 cd). | candlepower-to-candela | 0.981 |
+| Candlepower to Lumens – Treat candlepower as a luminous intensity, then multiply by 4π to get flux. | candlepower-to-lumens | 12.3269 |
+| Lumens to Candlepower – Convert luminous flux back into candlepower by reversing the 4π factor. | lumens-to-candlepower | 0.081118 |
+| Candlepower to Foot-candles – At 1 foot, candlepower produces 0.981 foot-candles via its candela equivalent. | candlepower-to-foot-candles | 0.981 |
+| Foot-candles to Candlepower – Convert illuminance into candlepower using the 1-foot reference. | foot-candles-to-candlepower | 1.019367 |
+| Foot-candles to Lamberts – Convert illuminance into lamberts for diffuse-surface brightness (1 fc ≈ 0.0010764 L). | foot-candles-to-lamberts | 0.00107639 |
+| Lamberts to Foot-candles – One lambert gives about 929 foot-candles on a Lambertian surface. | lamberts-to-foot-candles | 929.03 |
+| Lamberts to Lux – A lambert equals 10,000 lux on a perfectly diffusing target. | lamberts-to-lux | 10000 |
+| Lux to Lamberts – Translate lux into lamberts by dividing by 10,000 for diffuse luminance. | lux-to-lamberts | 0.0001 |
+| Lamberts to Nits – One lambert is about 3,183 cd/m² (nits). | lamberts-to-nits | 3183.09886184 |
+| Nits to Lamberts – Convert surface brightness back into lamberts using the 1/π² scaling. | nits-to-lamberts | 0.0003141593 |
+| Foot-lamberts to Lux – A foot-lambert is about 10.764 lux on a Lambertian patch. | foot-lamberts-to-lux | 10.764 |
+| Lux to Foot-lamberts – Convert lux into foot-lamberts (1 lux ≈ 0.092903 ft-L). | lux-to-foot-lamberts | 0.09290304 |
+| Foot-lamberts to Nits – Express foot-lamberts as nits (1 ft-L ≈ 3.426259 cd/m²). | foot-lamberts-to-nits | 3.426259108 |
+| Nits to Foot-lamberts – Translate luminance measured in nits into foot-lamberts. | nits-to-foot-lamberts | 0.292 |
+| Phot to Lux – One phot equals 10,000 lux for film-lighting references. | phot-to-lux | 10000 |
+| Lux to Phot – Convert lux into phots to match old photographic light charts. | lux-to-phot | 0.0001 |
+| Phot to Lamberts – Phot and lambert coincide (1 phot = 1 lambert). | phot-to-lamberts | 1 |
+| Lamberts to Phot – Flip lamberts back into phots. | lamberts-to-phot | 1 |
+| Phot to Foot-lamberts – One phot (10,000 lux) equals about 929 foot-lamberts. | phot-to-foot-lamberts | 929.03 |
+| Foot-lamberts to Phot – Express foot-lamberts as phots (1 ft-L ≈ 0.0010764 phot). | foot-lamberts-to-phot | 0.00107639 |
+| Lumens to Lux per square meter – Spread lumens over 1 m² to get lux. | lumens-to-lux-per-square-meter | 1 |
+| Lux to Lumens per square meter – Treat lux as lumens on each square meter. | lux-to-lumens-per-square-meter | 1 |
+| Foot-candles to Phot – Convert foot-candles into phots via the 10,000 lux anchor. | foot-candles-to-phot | 0.00107639 |
+| Phot to Foot-candles – Express phots as foot-candles for practical light meter use. | phot-to-foot-candles | 929.03 |
+| Lumens to Nits per square meter – A lumen/m² (lux) equals about 0.31831 nits under Lambertian lighting. | lumens-to-nits-per-square-meter | 0.318309886 |
+| Nits to Lumens per square meter – Back-convert nits into lumens/m² using π. | nits-to-lumens-per-square-meter | 3.141592654 |
+| Lumens to Foot-lamberts per square meter – One lux equals 0.092903 foot-lamberts. | lumens-to-foot-lamberts-per-square-meter | 0.09290304 |
+| Foot-lamberts to Lumens per square meter – Translate foot-lamberts into lux for metric flux (multiply by 10.7639). | foot-lamberts-to-lumens-per-square-meter | 10.7639 |
+| Stilbs to Nits – A stilb equals 10,000 nits for high-luminance scopes. | stilbs-to-nits | 10000 |
+| Nits to Stilbs – Convert nits into the CGS stilb scale (1 nit = 0.0001 stilb). | nits-to-stilbs | 0.0001 |
+| Stilbs to Lux – Multiply stilbs by π to get the matching lux value (≈ 31,415.93 lux). | stilbs-to-lux | 31415.92654 |
+| Lux to Stilbs – Express lux as stilbs by dividing by π × 10,000. | lux-to-stilbs | 0.00003183 |
 | Mach to Feet per Second – Convert Mach number to feet per second (approximate sea-level speed of sound). | mach-to-feet-per-second | 1116.447 |
 | Mach to Kilometers per Hour – Convert Mach number to km/h. | mach-to-kilometers-per-hour | 1225.044 |
 | Mach to Knots – Convert Mach number to knots. | mach-to-knots | 661.47 |
diff --git a/hdyc-svelte/src/lib/data/calculators.ts b/hdyc-svelte/src/lib/data/calculators.ts
index 7917180..4e03794 100644
--- a/hdyc-svelte/src/lib/data/calculators.ts
+++ b/hdyc-svelte/src/lib/data/calculators.ts
@@ -670,6 +670,46 @@ export const calculators: CalculatorDef[] = [
   {"slug": "long-tons-to-pounds", "name": "Long Tons to Pounds", "category": "weight", "type": "standard", "teaser": "Convert long tons to pounds.", "labels": {"in1": "Long Tons", "in2": "Pounds"}, "factor": 2240.0},
   {"slug": "long-tons-to-short-tons", "name": "Long Tons to Short Tons", "category": "weight", "type": "standard", "teaser": "Convert long tons to short tons.", "labels": {"in1": "Long Tons", "in2": "Short Tons"}, "factor": 1.12},
   {"slug": "lux-to-foot-candles", "name": "Lux to Foot-candles", "category": "light", "type": "standard", "teaser": "Convert illuminance from lux to foot-candles.", "labels": {"in1": "Lux", "in2": "Foot-candles"}, "factor": 0.09290304, "hidden": true},
+  {"slug": "candela-to-foot-candles", "name": "Candela to Foot-candles", "category": "light", "type": "standard", "teaser": "At 1 foot away, one candela yields one foot-candle of illuminance.", "labels": {"in1": "Candela", "in2": "Foot-candles"}},
+  {"slug": "foot-candles-to-candela", "name": "Foot-candles to Candela", "category": "light", "type": "standard", "teaser": "Convert illuminance in foot-candles into a luminous intensity at 1 foot.", "labels": {"in1": "Foot-candles", "in2": "Candela"}, "hidden": true},
+  {"slug": "candela-to-lux-at-foot", "name": "Candela to Lux (1 ft)", "category": "light", "type": "standard", "teaser": "One candela at a 1-foot distance produces about 10.7639 lux on the target plane.", "labels": {"in1": "Candela", "in2": "Lux (1 ft)"}, "factor": 10.7639},
+  {"slug": "lux-to-candela-at-foot", "name": "Lux to Candela (1 ft)", "category": "light", "type": "standard", "teaser": "Turn lux measured 1 foot away into the equivalent candela luminous intensity.", "labels": {"in1": "Lux", "in2": "Candela (1 ft)"}, "factor": 0.09290304},
+  {"slug": "candela-to-nits", "name": "Candela to Nits", "category": "light", "type": "standard", "teaser": "Treat 1 candela distributed over 1 square meter as 1 nit for comparing luminance.", "labels": {"in1": "Candela", "in2": "Nits"}},
+  {"slug": "nits-to-candela", "name": "Nits to Candela", "category": "light", "type": "standard", "teaser": "Assume a 1-square-meter patch to convert nits into candela.", "labels": {"in1": "Nits", "in2": "Candela"}, "hidden": true},
+  {"slug": "candela-to-candlepower", "name": "Candela to Candlepower", "category": "light", "type": "standard", "teaser": "Translate candela intensity into the legacy candlepower scale (1 cd \u2248 1.01937 cp).", "labels": {"in1": "Candela", "in2": "Candlepower"}, "factor": 1.019367},
+  {"slug": "candlepower-to-candela", "name": "Candlepower to Candela", "category": "light", "type": "standard", "teaser": "Flip historical candlepower values back into modern candelas (1 cp \u2248 0.981 cd).", "labels": {"in1": "Candlepower", "in2": "Candela"}, "factor": 0.981, "hidden": true},
+  {"slug": "candlepower-to-lumens", "name": "Candlepower to Lumens", "category": "light", "type": "standard", "teaser": "Treat candlepower as a luminous intensity, then multiply by 4\u03c0 to get flux.", "labels": {"in1": "Candlepower", "in2": "Lumens"}, "factor": 12.3269},
+  {"slug": "lumens-to-candlepower", "name": "Lumens to Candlepower", "category": "light", "type": "standard", "teaser": "Convert luminous flux back into candlepower by reversing the 4\u03c0 factor.", "labels": {"in1": "Lumens", "in2": "Candlepower"}, "factor": 0.081118, "hidden": true},
+  {"slug": "candlepower-to-foot-candles", "name": "Candlepower to Foot-candles", "category": "other", "type": "standard", "teaser": "At 1 foot, candlepower produces 0.981 foot-candles via its candela equivalent.", "labels": {"in1": "Candlepower", "in2": "Foot-candles"}, "factor": 0.981, "hidden": true},
+  {"slug": "foot-candles-to-candlepower", "name": "Foot-candles to Candlepower", "category": "other", "type": "standard", "teaser": "Convert illuminance into candlepower using the 1-foot reference.", "labels": {"in1": "Foot-candles", "in2": "Candlepower"}, "factor": 1.019367},
+  {"slug": "foot-candles-to-lamberts", "name": "Foot-candles to Lamberts", "category": "other", "type": "standard", "teaser": "Convert illuminance into lamberts for diffuse-surface brightness (1 fc \u2248 0.0010764 L).", "labels": {"in1": "Foot-candles", "in2": "Lamberts"}, "factor": 0.00107639, "hidden": true},
+  {"slug": "lamberts-to-foot-candles", "name": "Lamberts to Foot-candles", "category": "other", "type": "standard", "teaser": "One lambert gives about 929 foot-candles on a Lambertian surface.", "labels": {"in1": "Lamberts", "in2": "Foot-candles"}, "factor": 929.03},
+  {"slug": "lamberts-to-lux", "name": "Lamberts to Lux", "category": "light", "type": "standard", "teaser": "A lambert equals 10,000 lux on a perfectly diffusing target.", "labels": {"in1": "Lamberts", "in2": "Lux"}, "factor": 10000.0},
+  {"slug": "lux-to-lamberts", "name": "Lux to Lamberts", "category": "light", "type": "standard", "teaser": "Translate lux into lamberts by dividing by 10,000 for diffuse luminance.", "labels": {"in1": "Lux", "in2": "Lamberts"}, "factor": 0.0001, "hidden": true},
+  {"slug": "lamberts-to-nits", "name": "Lamberts to Nits", "category": "other", "type": "standard", "teaser": "One lambert is about 3,183 cd/m\u00b2 (nits).", "labels": {"in1": "Lamberts", "in2": "Nits"}, "factor": 3183.09886184},
+  {"slug": "nits-to-lamberts", "name": "Nits to Lamberts", "category": "other", "type": "standard", "teaser": "Convert surface brightness back into lamberts using the 1/\u03c0\u00b2 scaling.", "labels": {"in1": "Nits", "in2": "Lamberts"}, "factor": 0.0003141593, "hidden": true},
+  {"slug": "foot-lamberts-to-lux", "name": "Foot-lamberts to Lux", "category": "light", "type": "standard", "teaser": "A foot-lambert is about 10.764 lux on a Lambertian patch.", "labels": {"in1": "Foot-lamberts", "in2": "Lux"}, "factor": 10.764},
+  {"slug": "lux-to-foot-lamberts", "name": "Lux to Foot-lamberts", "category": "light", "type": "standard", "teaser": "Convert lux into foot-lamberts (1 lux \u2248 0.092903 ft-L).", "labels": {"in1": "Lux", "in2": "Foot-lamberts"}, "factor": 0.09290304, "hidden": true},
+  {"slug": "foot-lamberts-to-nits", "name": "Foot-lamberts to Nits", "category": "other", "type": "standard", "teaser": "Express foot-lamberts as nits (1 ft-L \u2248 3.426259 cd/m\u00b2).", "labels": {"in1": "Foot-lamberts", "in2": "Nits"}, "factor": 3.426259108},
+  {"slug": "nits-to-foot-lamberts", "name": "Nits to Foot-lamberts", "category": "other", "type": "standard", "teaser": "Translate luminance measured in nits into foot-lamberts.", "labels": {"in1": "Nits", "in2": "Foot-lamberts"}, "factor": 0.292, "hidden": true},
+  {"slug": "phot-to-lux", "name": "Phot to Lux", "category": "light", "type": "standard", "teaser": "One phot equals 10,000 lux for film-lighting references.", "labels": {"in1": "Phot", "in2": "Lux"}, "factor": 10000.0},
+  {"slug": "lux-to-phot", "name": "Lux to Phot", "category": "light", "type": "standard", "teaser": "Convert lux into phots to match old photographic light charts.", "labels": {"in1": "Lux", "in2": "Phot"}, "factor": 0.0001, "hidden": true},
+  {"slug": "phot-to-lamberts", "name": "Phot to Lamberts", "category": "other", "type": "standard", "teaser": "Phot and lambert coincide (1 phot = 1 lambert).", "labels": {"in1": "Phot", "in2": "Lamberts"}, "hidden": true},
+  {"slug": "lamberts-to-phot", "name": "Lamberts to Phot", "category": "other", "type": "standard", "teaser": "Flip lamberts back into phots.", "labels": {"in1": "Lamberts", "in2": "Phot"}},
+  {"slug": "phot-to-foot-lamberts", "name": "Phot to Foot-lamberts", "category": "other", "type": "standard", "teaser": "One phot (10,000 lux) equals about 929 foot-lamberts.", "labels": {"in1": "Phot", "in2": "Foot-lamberts"}, "factor": 929.03},
+  {"slug": "foot-lamberts-to-phot", "name": "Foot-lamberts to Phot", "category": "other", "type": "standard", "teaser": "Express foot-lamberts as phots (1 ft-L \u2248 0.0010764 phot).", "labels": {"in1": "Foot-lamberts", "in2": "Phot"}, "factor": 0.00107639, "hidden": true},
+  {"slug": "lumens-to-lux-per-square-meter", "name": "Lumens to Lux per square meter", "category": "length", "type": "standard", "teaser": "Spread lumens over 1 m\u00b2 to get lux.", "labels": {"in1": "Lumens", "in2": "Lux per square meter"}},
+  {"slug": "lux-to-lumens-per-square-meter", "name": "Lux to Lumens per square meter", "category": "length", "type": "standard", "teaser": "Treat lux as lumens on each square meter.", "labels": {"in1": "Lux", "in2": "Lumens per square meter"}},
+  {"slug": "foot-candles-to-phot", "name": "Foot-candles to Phot", "category": "other", "type": "standard", "teaser": "Convert foot-candles into phots via the 10,000 lux anchor.", "labels": {"in1": "Foot-candles", "in2": "Phot"}, "factor": 0.00107639, "hidden": true},
+  {"slug": "phot-to-foot-candles", "name": "Phot to Foot-candles", "category": "other", "type": "standard", "teaser": "Express phots as foot-candles for practical light meter use.", "labels": {"in1": "Phot", "in2": "Foot-candles"}, "factor": 929.03},
+  {"slug": "lumens-to-nits-per-square-meter", "name": "Lumens to Nits per square meter", "category": "length", "type": "standard", "teaser": "A lumen/m\u00b2 (lux) equals about 0.31831 nits under Lambertian lighting.", "labels": {"in1": "Lumens", "in2": "Nits per square meter"}, "factor": 0.318309886},
+  {"slug": "nits-to-lumens-per-square-meter", "name": "Nits to Lumens per square meter", "category": "length", "type": "standard", "teaser": "Back-convert nits into lumens/m\u00b2 using \u03c0.", "labels": {"in1": "Nits", "in2": "Lumens per square meter"}, "factor": 3.141592654},
+  {"slug": "lumens-to-foot-lamberts-per-square-meter", "name": "Lumens to Foot-lamberts per square meter", "category": "length", "type": "standard", "teaser": "One lux equals 0.092903 foot-lamberts.", "labels": {"in1": "Lumens", "in2": "Foot-lamberts per square meter"}, "factor": 0.09290304},
+  {"slug": "foot-lamberts-to-lumens-per-square-meter", "name": "Foot-lamberts to Lumens per square meter", "category": "length", "type": "standard", "teaser": "Translate foot-lamberts into lux for metric flux (multiply by 10.7639).", "labels": {"in1": "Foot-lamberts", "in2": "Lumens per square meter"}, "factor": 10.7639},
+  {"slug": "stilbs-to-nits", "name": "Stilbs to Nits", "category": "other", "type": "standard", "teaser": "A stilb equals 10,000 nits for high-luminance scopes.", "labels": {"in1": "Stilbs", "in2": "Nits"}, "factor": 10000.0},
+  {"slug": "nits-to-stilbs", "name": "Nits to Stilbs", "category": "other", "type": "standard", "teaser": "Convert nits into the CGS stilb scale (1 nit = 0.0001 stilb).", "labels": {"in1": "Nits", "in2": "Stilbs"}, "factor": 0.0001, "hidden": true},
+  {"slug": "stilbs-to-lux", "name": "Stilbs to Lux", "category": "light", "type": "standard", "teaser": "Multiply stilbs by \u03c0 to get the matching lux value (\u2248 31,415.93 lux).", "labels": {"in1": "Stilbs", "in2": "Lux"}, "factor": 31415.92654},
+  {"slug": "lux-to-stilbs", "name": "Lux to Stilbs", "category": "light", "type": "standard", "teaser": "Express lux as stilbs by dividing by \u03c0 \u00d7 10,000.", "labels": {"in1": "Lux", "in2": "Stilbs"}, "factor": 3.183e-05, "hidden": true},
   {"slug": "mach-to-feet-per-second", "name": "Mach to Feet per Second", "category": "length", "type": "standard", "teaser": "Convert Mach number to feet per second (approximate sea-level speed of sound).", "labels": {"in1": "Mach", "in2": "Feet per Second"}, "factor": 1116.447},
   {"slug": "mach-to-kilometers-per-hour", "name": "Mach to Kilometers per Hour", "category": "length", "type": "standard", "teaser": "Convert Mach number to km/h.", "labels": {"in1": "Mach", "in2": "Kilometers per Hour"}, "factor": 1225.044},
   {"slug": "mach-to-knots", "name": "Mach to Knots", "category": "speed", "type": "standard", "teaser": "Convert Mach number to knots.", "labels": {"in1": "Mach", "in2": "Knots"}, "factor": 661.47},