Estimate the electrical capacity a satellite mission must provide from its continuous bus load, peak payload load, mission duration, design margin, and usable battery depth. The result separates energy capacity from instantaneous power so early spacecraft concepts do not confuse watt-hours with watts.
Base energy = base load × autonomy. Peak energy = peak load × peak time. Required energy = (base energy + peak energy) × (1 + margin). Battery capacity = required energy ÷ usable depth.
Treat the main result as an engineering estimate based on the stated inputs. Compare it with the applicable mission requirement and retain enough traceability to update the result when assumptions change.
This calculator supports early trade studies and does not replace mission-specific simulation, environmental analysis, or professional engineering review.
At 180 W for 12 hours plus a 320 W payload for 2.5 hours, a 25% margin produces 3,700 Wh of required energy and a 5,286 Wh nominal battery at 70% usable depth.
It uses the values shown in the input panel and the formula stated on this page. It does not add hidden operational or environmental allowances.
Yes. Decimal values are accepted within each field’s displayed range, and calculations retain precision until the result is formatted.
Use a value justified by your project’s maturity, uncertainty policy, and verification plan rather than treating the default as a universal recommendation.
No. It is a first-pass estimate for trade studies. Verify the design with subsystem models, test data, and mission-specific constraints.
Zero is accepted where it represents a physically meaningful absence of load, loss, background, duty, or maneuver demand. Inputs used as divisors must remain above zero.
| Item | Use |
|---|---|
| Primary inputs | Enter values in the units printed beside each field. |
| Margin or reserve | Applied only where stated in the formula. |
| Displayed result | Rounded for readability; internal math keeps full precision. |