Net ownership cost = purchase + required setup + expected repairs − end-of-period resale. Annual cost = net ownership cost ÷ years. Both options use the same years so the comparison shares a time horizon.

With the sample amounts, A costs 85,000 in total (28,333.33/year); B costs 90,000 (30,000/year). A is lower by 5,000 over three years. These are illustrative inputs, not current product prices.

Resale is uncertain; test the result with resale set to zero. Costs are not discounted for inflation or financing. Add subscriptions, insurance and energy to setup/repairs if they differ materially. Both devices must satisfy your work, repair-access and security-support needs over the chosen period. A low cost cannot establish suitability.

Read the cost-per-supported-year guide →

Repair cost = repair quote + other future costs − repaired device resale at period end. Replacement cost = replacement price + setup + future maintenance − sale of current device now − replacement resale at period end. Divide each by the same months.

Sample: repair = 12,000 + 3,000 − 10,000 = 5,000. Replace = 80,000 + 5,000 + 5,000 − 5,000 − 35,000 = 50,000. Difference = 45,000 over 24 months. A negative net cost can occur when assumed resale exceeds future spending; it is not a profit calculation and ignores the price already paid for the current device.

The tool does not diagnose faults or predict repair success. Downtime, warranty quality, repeat-failure risk and software support require separate checks. Use zero resale and a higher maintenance allowance as a stress test.

Read the repair-cost checklist →

Reported capacity ratio (%) = full-charge capacity ÷ design capacity × 100. Example: 40,000 mWh ÷ 50,000 mWh = 80%. This describes estimated stored energy relative to the design value, not the current charge level or a measured runtime.

Read the full Windows battery-report interpretation guide →

On Windows 11, generate the built-in report using powercfg /batteryreport and open the file at the path it reports. Some devices omit or estimate these values. Verify surprising readings against the device maker’s diagnostic tool; a replacement battery or reporting variation can affect the ratio.

No universal replacement threshold is applied. Capacity, shutdowns, your required runtime and physical condition matter together. Stop using a device with a swollen battery and arrange qualified service; do not press or puncture it.

Source: Microsoft battery-care and report instructions · Understand cycle count

Daily kWh = (active watts × active hours + idle watts × idle hours) ÷ 1,000. Period cost = daily kWh × days × rate. Annual estimate uses the same daily pattern for 365 days.

Sample: (65 × 5 + 8 × 3) ÷ 1,000 = 0.349 kWh/day. Over 30 days this is 10.47 kWh, or 628.20 at a rate of 60 per kWh. Annual use would be 127.385 kWh if the same pattern continued every day.

Read the complete desk-power measurement guide →

The remaining daily hours are assumed off with zero consumption. Include real standby hours if the device remains plugged in. Active and idle hours must total no more than 24. This is a marginal energy estimate, excluding fixed charges, time-of-use differences, taxes and tariff slabs unless you include them in the rate. It is not a prediction of your whole utility bill.