LED Savings Calculator

LED Savings is evaluated from Old Bulb Wattage, Replacement LED Wattage and Number of Bulbs. The calculation reports Annual Energy Saved, Annual Dollar Savings and Payback Period.

Results

Thanks — we’ve logged this for review.

About the LED Savings Calculator

LED Savings is treated here as a quantitative relation between Old Bulb Wattage, Replacement LED Wattage, Number of Bulbs and Hours Used per Day and Annual Energy Saved, Annual Dollar Savings, Payback Period and Annual CO₂ Reduction.

The calculator uses a multi formula configuration. Each reported value is read as a direct evaluation of the stored rules with the declared field formats and units.

Formula basis:
Savings (watts) = (old watts - LED watts) x number of bulbs
Annual kWh saved = watts saved x hours per day x 365 / 1,000
Annual $ saved = kWh x electricity rate
Payback (months) = upfront cost / monthly savings

Interpret the outputs in the order shown by the result fields. Optional inputs affect only the outputs that depend on those variables.

Formula & How It Works

The calculation applies the following relations exactly as recorded in the metadata:

Savings (watts) = (old watts - LED watts) x number of bulbs
Annual kWh saved = watts saved x hours per day x 365 / 1,000
Annual $ saved = kWh x electricity rate
Payback (months) = upfront cost / monthly savings

Each output field is produced by substituting the supplied inputs into the relevant relation and then applying the declared rounding or text format.

Worked Examples

Example 1: 20 bulbs: replace 60W incandescent with 10W LED, 4 hrs/day, $0.16/kWh, $4/bulb

Inputs

old_watts: 60 led_watts: 10 num_bulbs: 20 hours_day: 4 elec_rate: 0.16 led_cost: 4
Annual Energy Saved: 1,460 kWh/year. Annual Dollar Savings: $233.6/year. Payback Period: 4.1 months. Annual CO₂ Reduction: 1,245 lbs CO₂/year

With Old Bulb Wattage = 60, Replacement LED Wattage = 10, Number of Bulbs = 20 and Hours Used per Day = 4 as the stated inputs, the result is Annual Energy Saved = 1,460 kWh/year, Annual Dollar Savings = $233.6/year and Payback Period = 4.1 months. Each value corresponds to the declared output fields.

Example 2: Replace 30 bulbs: 100W incandescent with 15W LED, 5 hrs/day, $0.20/kWh, $5/bulb

Inputs

old_watts: 100 led_watts: 15 num_bulbs: 30 hours_day: 5 elec_rate: 0.2 led_cost: 5
Annual Energy Saved: 4,654 kWh/year. Annual Dollar Savings: $930.75/year. Payback Period: 1.9 months. Annual CO₂ Reduction: 3,970 lbs CO₂/year

With Old Bulb Wattage = 100, Replacement LED Wattage = 15, Number of Bulbs = 30 and Hours Used per Day = 5 as the stated inputs, the result is Annual Energy Saved = 4,654 kWh/year, Annual Dollar Savings = $930.75/year and Payback Period = 1.9 months. Each value corresponds to the declared output fields.

Example 3: Upgrade 10 CFL bulbs (23W) to LED (10W), 3 hrs/day, $0.14/kWh, $3/bulb

Inputs

old_watts: 23 led_watts: 10 num_bulbs: 10 hours_day: 3 elec_rate: 0.14 led_cost: 3
Annual Energy Saved: 142 kWh/year. Annual Dollar Savings: $19.93/year. Payback Period: 18.1 months. Annual CO₂ Reduction: 121 lbs CO₂/year

With Old Bulb Wattage = 23, Replacement LED Wattage = 10, Number of Bulbs = 10 and Hours Used per Day = 3 as the stated inputs, the result is Annual Energy Saved = 142 kWh/year, Annual Dollar Savings = $19.93/year and Payback Period = 18.1 months. Each value corresponds to the declared output fields.

Example 4: All lighting in large commercial-style home: 50 bulbs mix, 75W avg to 12W LED, 6 hrs/day, $0.18/kWh, $6/bulb

Inputs

old_watts: 75 led_watts: 12 num_bulbs: 50 hours_day: 6 elec_rate: 0.18 led_cost: 6
Annual Energy Saved: 6,899 kWh/year. Annual Dollar Savings: $1,241.73/year. Payback Period: 2.9 months. Annual CO₂ Reduction: 5,884 lbs CO₂/year

With Old Bulb Wattage = 75, Replacement LED Wattage = 12, Number of Bulbs = 50 and Hours Used per Day = 6 as the stated inputs, the result is Annual Energy Saved = 6,899 kWh/year, Annual Dollar Savings = $1,241.73/year and Payback Period = 2.9 months. Each value corresponds to the declared output fields.

Common Use Cases

  • Calculate savings from switching to LED bulbs
  • Compare incandescent vs CFL vs LED energy costs
  • Determine payback period for LED bulb upgrades