SpecCalc Hub · Medium
UPS Runtime Calculator
Estimate UPS runtime from battery configuration, load, efficiency, and usable capacity.
PDF export during launch
Launch offer: free for early adopters.
No payment is required during the launch period.
No account required. Calculation history is not stored.
Formula
battery_wh = voltage * Ah * count usable_wh = battery_wh * usable_capacity * efficiency runtime_hours = usable_wh / load_w load_percent = load_w / (VA * PF) * 100
Assumptions
- Inputs are user-provided.
- Results are preliminary estimates.
- Battery is healthy and load is constant.
Limitations
- Manufacturer runtime curves may differ significantly.
Sources / methodology
Uses battery Wh adjusted by usable capacity and efficiency.
- Formula version
- 1.0.6
- Formula review date
- 2026-05-25
Source links
Quick answer: UPS Runtime Calculator estimates battery energy from transparent input parameters and a visible formula. Results are informational estimates only and should be checked against the stated assumptions and limitations.
Input parameters
- Load (W): 300 W
- Battery voltage (V): 12 V
- Battery capacity (Ah): 9 Ah
- Battery count (pcs): 2 pcs
- UPS efficiency (%): 85 %
- Usable capacity (%): 80 %
- UPS rating (VA): 1,000 VA
- UPS power factor (PF): 0.6 PF
Output values
- Battery energy (Wh)
- Usable energy (Wh)
- Runtime (minutes)
- UPS load (%)
Step-by-step example
- Enter values into the calculator fields.
- Run the calculation and review the result values.
- Compare the result with the assumptions, limitations and sources below.
Worked examples
Small load example
Use UPS Runtime Calculator with realistic household or workshop inputs first, then compare the estimate with a bill, label, nameplate, or manufacturer data.
Input sensitivity example
Change one major input at a time to see which variable drives the estimate most before you compare options or make a purchase decision.
Caution example
If inputs are approximate, treat the result as a planning number and rerun the calculator with better data before making a purchase decision.
Common mistakes
- Keep all units consistent with the field labels.
- Check whether the input values are measured, nameplate values or planning assumptions.
- Review the stated assumptions and limitations before using the estimate.
What to check next
Check the inputs, limitations, sources and related calculators before using the estimate in a real decision.
FAQ
What does UPS Runtime Calculator calculate?
UPS Runtime Calculator estimates battery energy from transparent input parameters and a visible formula. Results are informational estimates only and should be checked against the stated assumptions and limitations.
What formula does this calculator use?
The visible formula starts with: battery_wh = voltage * Ah * count. The full formula, assumptions and limitations are shown on the page.
Are the results stored?
No account is required and SpecCalc Hub does not save personal calculation history.
Related calculators
This calculator provides an estimate for informational purposes only. It is not a certified engineering design, electrical safety approval, or professional installation recommendation. Always verify final decisions with a qualified professional and applicable local codes.