Time-of-use tariffs reward moving flexible loads out of expensive peak hours. This guide walks through the time of use electricity savings calculator: shiftable kWh per month, peak $/kWh, off-peak $/kWh, and the spread that becomes real bill savings.
Benefits
- Simple formula: monthly savings = shiftable kWh × (peak rate − off-peak rate).
- Annual savings line scales monthly results for budget and ROI decisions.
- Energy-rate only—no demand charges—so results match residential TOU shifting.
How it works
- Estimate how many kWh per month you can move from peak to off-peak windows.
- Enter your utility peak and off-peak $/kWh from the rate schedule.
- Read monthly and annual savings plus the $/kWh spread driving the result.
FAQ
How do I calculate time-of-use electricity savings?
Monthly savings ≈ shiftable kWh × (peak $/kWh − off-peak $/kWh). Example: 350 kWh/mo moved from $0.42 peak to $0.11 off-peak → spread $0.31/kWh → 350 × 0.31 ≈ $108.50/mo (~$1,302/yr). Only count kWh you can realistically reschedule.
What loads are good candidates for TOU shifting?
EV charging, dishwashers, clothes dryers, pool pumps, and water-heater timers are common shift targets. Fixed loads—refrigerators, always-on networking—stay wherever they run. Sum flexible kWh from smart plugs or interval data when you have it.
Does this include demand charges or flat-rate comparison?
No—this tool isolates energy-rate savings from moving kWh between TOU periods. Commercial demand charges and flat vs. TOU plan choice are separate calculators. Use this when you are already on TOU and want dollars from behavior change.
Technical specifications
- Savings per kWh = peak_rate − off_peak_rate (≥ 0).
- Monthly savings = shiftable_kWh × savings_per_kWh.
- Annual savings ≈ monthly_savings × 12.
- Related: tou-shifting-savings, peak-shaving-potential, electricity-rate-plan.
The spread is the whole story
TOU savings are not mystical—they are kWh moved across a price gap. A wide peak-to-off-peak spread with many shiftable kWh prints large monthly dollars. A narrow spread or mostly fixed load prints small savings even on the same tariff. Enter real rates from your bill rider, not a national average.
Shiftable kWh is a habit number
Do not count every monthly kWh as movable. Refrigerators and baseline HVAC stay put. EV charging from 11 p.m. to 6 a.m., delayed dishwasher starts, and laundry after 9 p.m. are the numerator. Underestimate first, then add kWh as automations prove out—optimistic shifting math disappoints on the first real bill.
Annual line funds automation
A $90/month TOU win is $1,080/year—enough to justify a smart EV charger schedule, timer plugs, or a few hours wiring a load controller. The calculator’s annual savings line turns behavior into a budget line item so peak shaving competes fairly with bulb swaps and insulation on payback.