Skip to main content
∑
Conversion

Lumens ⇄ Lux Converter (lm ⇄ lx)

Lumens (lm) measure the total light a source emits; lux (lx) measure how many lumens land on each square metre of surface — the real "is the room bright enough" metric. The relation is the area conversion lx = lm ÷ m². Enter the lumens of your bulb or fixture and the lit area; the tool returns the illuminance in lux and compares it against the EN 12464-1 / IESNA RP-1 task lighting bands (general office 300–500 lx, desk-task 500–750 lx, etc.). Switch to "Target → lumens" mode to enter a target lux level and room area, and the tool tells you how many total lumens you need — handy when shopping for LED bulbs or sizing a new lighting layout.

Illuminance (lx)

40 lx

Common targets (EN 12464-1)

  • 50 lx · Corridor / storage
  • 150 lx · Living / dining ambient
  • 300 lx · General office
  • 500 lx · Office task work
  • 1,000 lx · Drafting / detailed work
  • 10,000 lx · Overcast daylight

Assumes flux is spread evenly over the lit area. Real-room illuminance depends on fixture beam, mounting height and wall reflectance.

Formula

lx = lm ÷ A(m²) ; lm = lx × A(m²) ; 1 ft² = 0.09290304 m²

Frequently asked

Why does my "60W equivalent = 800 lm" LED bulb feel dim in my room?

Lumens is what the bulb emits in total; what you feel is the illuminance (lux) on your desk or floor. An 800-lm LED bulb spread evenly across a 20 m² living room gives only 40 lx — well below the 300–500 lx EN 12464-1 / IESNA recommends for reading. To hit a comfortable 300 lx in that room you need 300 × 20 = 6,000 lm of total flux: roughly seven or eight 800-lm bulbs, or one to two high-output (3,000+ lm) ceiling panels. And that is the theoretical even-spread value; real rooms lose 20–30 % to beam angle, furniture obstruction and wall reflectance, so add a safety margin. Practical workflow: use the tool's "target → lumens" mode, decide your total lumen budget first, then split it across several fixtures.

How do lumens relate to watts? Why do old bulbs use "60 W"?

Watts measure power consumption, not light output. Old incandescent bulbs were ~10–17 lm/W, so a 60 W bulb delivered about 800 lm — and for decades "60 W" became shorthand for "about that bright". LEDs are 5–10× more efficient (80–150 lm/W), so a 9 W LED already pushes 800 lm. So: (1) shop by the lumens number on the box, not the watts; (2) at the same 800 lm an LED saves ~85 % electricity vs incandescent; (3) higher lm/W means efficient, not necessarily good light — also check CRI (colour rendering, aim ≥ 80) and CCT (colour temperature, 2700–3000 K for bedrooms, 4000–5000 K for offices). EU regulation 1369/2017 requires both lumens and watts on the label, and most quality LED packaging worldwide now follows suit.

For indoor grow lights or photography, should I use lux or PAR / PPFD?

It depends on the use case. Lux measures visible light weighted by human eye sensitivity, but plants photosynthesise using 400–700 nm photosynthetically active radiation (PAR), so horticulture quotes photosynthetic photon flux density (PPFD) in μmol/m²/s, not lux. A rough conversion for white-light LEDs is 1 lx ≈ 0.015 μmol/m²/s (sunlight is ~0.018), but red- or blue-only LEDs have very different conversion factors because their spectra do not match human-eye weighting. For photography, the human-weighted lx / EV is the right unit, though pro cinema crews still use footcandles or stops (logs of lux). Practical rule: (1) general indoor lighting (home, office) → lx; (2) commercial horticulture → PPFD; (3) photography / film → lx or EV / stops. This tool is a lux tool; it does not output PPFD.

Related tools

Length Unit Converter

Cm, m, km, in, ft, yd, mi — common length units, converted instantly.

Temperature Converter

Convert between Celsius (°C), Fahrenheit (°F) and Kelvin (K) instantly.

Shoe Size Converter (US / UK / EU / CM)

Enter your foot length or a size in any system to see the equivalent US / UK / EU and centimetre sizes.

Paper Size Reference

Pick a paper size (A0–A10, B / C series, Letter, Legal, card sizes) to see its mm / cm / inch / pixel dimensions.

Number Base Converter (Binary / Octal / Decimal / Hex)

Convert a number simultaneously between binary, octal, decimal and hexadecimal — useful for programmers, students and electronics work.

Aspect Ratio & Screen Size Calculator

From an aspect ratio and one side, find the other; or from a diagonal and ratio, get real width and height (4:3, 16:9, 21:9 …).

Data Storage Unit Converter (B/KB/MB/GB/TB)

Convert between bytes, KB, MB, GB, TB and PB — distinguishing decimal (1000-base, drive labels) from binary (1024-base, OS-reported).

RGB ↔ HEX ↔ HSL Color Converter

Convert between HEX (#RRGGBB), RGB(0–255) and HSL(0–360, 0–100, 0–100) instantly — with a live colour preview swatch.

Tire Size Calculator (Spec / Diameter / Speedometer Error)

Convert a P-metric tire spec (e.g. 225/65R17) into sidewall height, overall diameter, circumference and revolutions per km — and compare against a reference size to see speedometer error.

Energy Unit Converter (J / kJ / cal / kcal / kWh / BTU / Wh)

Convert between joules, kilojoules, calories, kilocalories, kilowatt-hours, BTU and watt-hours in a single view — for nutrition labels, electricity bills, heating and fuel comparisons.

Pressure Unit Converter

Convert between Pa, kPa, bar, mbar, atm, psi, mmHg, Torr and inHg in a single view — all the everyday pressure units.

Torque Unit Converter

Convert between N·m, kgf·m, kgf·cm, lbf·ft, lbf·in and ozf·in — all the torque units used on torque wrenches, bicycle bolts and car service specs.

Angle Unit Converter

Convert between degrees, radians, gradians, turns, arcminutes, arcseconds, milliradians and NATO mil — with live sin/cos/tan values for reference.

Fuel Economy Converter (MPG ⇄ L/100km)

Convert between L/100km, km/L, US MPG and UK (imperial) MPG — compare car efficiency figures across regions without arithmetic.

Power Unit Converter

Convert between W, kW, MW, mechanical horsepower (hp), metric horsepower (PS), BTU/hr, ft·lbf/s, cal/s, kcal/h and refrigeration tons in one view.

px ↔ rem ↔ em Converter

Pick a root font-size (defaults to 16 px) and convert any CSS pixel, rem, em, percentage or point value into the others, with a reference table for common sizes.

Alcohol ABV ↔ Proof Converter & Standard Drinks Calculator

Convert alcohol by volume (ABV %) to US proof and UK proof, plus compute grams of pure alcohol and "standard drinks" per pour for US / UK / AU / HK.

Bandwidth & Throughput Converter (Mbps ↔ MB/s)

Convert network bandwidth (kbps, Mbps, Gbps) to file-transfer rate (KB/s, MB/s, MiB/s) and estimate how long a given file size takes.

Weight / Mass Unit Converter

Kilograms, grams, milligrams, pounds, ounces, stones, tonnes, jin and tael — common mass units, converted instantly.

Battery mAh ↔ Wh Converter (Power Bank Airline Rules)

Enter battery capacity (mAh) and voltage (V) to get watt-hours (Wh) instantly — with a live IATA airline check (100 Wh / 160 Wh cut-offs).

International Bra Size Converter

Enter underbust and bust (or pick a local size) to convert bra sizes across US, UK, EU, AU and JP standards.

International Ring Size Converter

Enter inner circumference (mm) or diameter to cross-reference US, UK, EU, JP and HK ring sizes.

Area Unit Converter

Square metres, hectares, acres, square feet, square miles and more — common area units, converted instantly.

Volume / Capacity Unit Converter

Litres, millilitres, cubic metres, US and imperial gallons, quarts, pints, fluid ounces, cups, tablespoons and teaspoons — converted instantly.

Speed Unit Converter

Convert freely between km/h, mph, m/s, ft/s, knots and Mach number.

Color Contrast Ratio (WCAG) Calculator

Enter foreground and background hex colors to compute the WCAG 2.x contrast ratio (1:1 to 21:1) and see whether the pair passes AA / AAA accessibility levels for normal and large text.

AWG Wire Size Calculator

Look up the diameter (mm), cross-sectional area (mm²), resistance per kilometre and safe ampacity for any American Wire Gauge (AWG) size — handy for low-voltage wiring design.

Frequency Unit Converter (Hz / kHz / MHz / GHz)

Convert between Hz, kHz, MHz, GHz, THz, RPM and BPM — one input fills every other unit instantly.

Force Unit Converter (N / kN / lbf / kgf / dyne)

Convert between newtons (N), kilonewtons (kN), pound-force (lbf), kilogram-force (kgf), dyne and ounce-force (ozf) — bridging SI, imperial and CGS force units used in physics and engineering.

Magnetic Flux Density Converter (T / mT / µT / Gauss)

Convert magnetic flux density between tesla (T), millitesla (mT), microtesla (µT), gauss (G) and milligauss (mG) — handy for comparing MRI fields, Earth field, speakers and lab magnets across very different scales.

Volumetric (Dimensional) Weight Calculator (Air / Courier)

Enter parcel length × width × height and DIM divisor (IATA air 6000 cm³/kg, express 5000, UPS/FedEx US 139 in³/lb) to compute volumetric weight and compare it with actual weight to find the chargeable weight.

Polar ↔ Cartesian Coordinate Converter

Convert Cartesian (x, y) ↔ polar (r, θ) coordinates in either direction with a degree/radian toggle — useful for math, physics, engineering and game-development work.

Astronomical Distance Converter (ly / pc / AU / km)

Enter any distance and the tool converts it across metres, kilometres, miles, Earth–Moon distance, astronomical units (AU), light-years, parsecs and light-travel time — useful for astronomy, science fiction and classroom prep.

Map Scale Distance Converter

Enter a scale ratio (e.g. 1:25 000) and a measured map distance; the tool returns the real-world distance, or works in reverse from real distance to map distance — useful for hiking, map reading and town planning.

DMS ↔ Decimal Degrees Converter

Two-way conversion between degrees–minutes–seconds (D° M′ S″) and decimal degrees — the standard need when juggling GPS coordinates, astronomy, surveying and marine navigation. Supports signed values for south latitude and west longitude.

Hat Size Converter (Head Circumference → US/UK/EU/JP)

Enter your head circumference (cm or inches); the tool maps it to US (fitted and fractional), UK, EU (cm) and Japanese hat sizes plus the S/M/L/XL range — useful for buying New Era caps, fedoras, baseball caps and helmet liners online.

kW ⇄ Horsepower Converter (kW / HP / PS)

Convert between kilowatt (kW), mechanical horsepower (HP), metric horsepower (PS / cheval-vapeur), brake horsepower (BHP), and foot-pound-force per second — the standard unit set for cars, engines, generators and power tools across UK / US / EU / JP markings.