500 Wh vs 1,000 Wh
Four planning cases for a round 500 Wh label and a round 1,000 Wh label. Watt-hours say how long the load can run. Inverter watts say whether it runs at all. Sheets on this page were read 2026-10-23.
What the round labels deliver
Same order as js/calculator.js. Round the full quotient once, half-up, the way Math.round does. Do not round the middle steps and then keep going. DoD=0.90 is a planning fraction of the label. It is not a BMS guarantee. The 15% buffer is headroom, not a measured loss. The runtime check does not apply the buffer again on the way down.
| Label | 12 V / USB delivered | AC delivered |
|---|---|---|
| 500 Wh | 500 × 0.90 = 450 Wh | 500 × 0.81 = 405 Wh |
| 1,000 Wh | 1,000 × 0.90 = 900 Wh | 1,000 × 0.81 = 810 Wh |
Those four products are exact. A 1,000 Wh label is not 1,000 usable Wh. Class spans on this site, from the sizing walkthrough: results up to 512 Wh, then 513–1,152 Wh, then 1,153 Wh and up. Shop the buffered nameplate against the printed label, not the round class name. A two-day miss that still sits under 1,152 Wh is the ~1,000 Wh class, not an automatic step to 1,000 vs 2,000 Wh.
Weekend camp: 12 V fridge, phones, lights
One day and two days, solar = 0. The fridge figure is the CFX3 35 test point, the same 282 Wh/day used on camping fridge. The sheet lists 0.98 Ah/h at 12 V DC, ambient 90°F, internal 39°F, volume 36 L. 0.98 × 12 × 24 = 282.24, published as 282 Wh/day. Dometic’s runtime method is usable battery Ah ÷ that Ah/h. Their lead-acid note is a different battery. It is not this site’s 0.90 DoD.
The same electrical table prints rated DC current 7.5 A, rated AC power 50 W, and rated AC current 0.78 A at 120 V. 7.5 × 12 = 90 W. 0.78 × 120 = 93.6 W. Those two watt figures do not match the 50 W line. This page does not average them and does not use any of them as the day. Average power at the test point is 282 / 24 = 11.75 W. 50 W × 24 h = 1,200 Wh is the rated AC input held all day, not this test point.
| Load | Basis | Wh/day | Path |
|---|---|---|---|
| CFX3 35 | 0.98 Ah/h × 12 V × 24 h, published as 282 | 282 | 12 V, η=1.00 |
| Two phones | Apple 20 W USB-C adapter × 1 h × 2. Count and hours are this day. A phone often draws less, so 40 Wh is a ceiling. | 40 | USB, η=1.00 |
| Four Stanpro 67168 pucks | 2.2 W × 4 × 5 h. The sheet rates the puck at 2.2 W, 12 V. Four pucks and 5 h are this day. The hub is not sized here. | 44 | 12 V, η=1.00 |
| Camp day | 282 + 40 + 44 | 366 | One DC pass |
All on 12 V and USB, solar = 0. Steps are load ÷ 1.00, × 1.15, ÷ 0.90.
| Days | Steps | Exact | Nameplate |
|---|---|---|---|
| 1 | 366.000 → 420.900 → nameplate | 467.667 | 468 Wh |
| 2 | 732.000 → 841.800 → nameplate | 935.333 | 935 Wh |
366 × 1 × 1.15 / (0.90 × 1.00) = 467.667 → 468 Wh
366 × 2 × 1.15 / 0.90 = 935.333 → 935 Wh
Do not double the rounded day. 468 × 2 = 936. The two-day quotient is 935.333, which rounds to 935 Wh.
A 500 Wh label delivers 450 Wh on 12 V. 450 / 366 = 1.230 days, which is (450 / 366) × 24 = 29.508 hours at that day’s average. A 1,000 Wh label delivers 900 Wh: 900 / 366 = 2.459 days, 59.016 hours. The buffered plan is the shopping number. 468 Wh is under a 500 Wh label. 935 Wh is over it and under a 1,000 Wh label. One camp day on 12 V fits 500 Wh. Two days with no recharge are where 1,000 Wh is the floor.
Plugging the fridge into the inverter changes the path. Phones and pucks stay on USB and 12 V (84 Wh, η=1.00). The 282 Wh test point moves to η=0.90. Add the full quotients, then round once. The rounded passes are 400 + 107 = 507. The full sum is 507.703703…, shown below as 507.704, which rounds to 508 Wh. The three-decimal displays add to 400.370 + 107.333 = 507.703, one thousandth under that 507.704. Two days: the rounded passes add to 801 + 215 = 1,016. The full sum is 1,015.407407…, which rounds to 1,015 Wh. The displays add to 800.741 + 214.667 = 1,015.408.
| Days | Fridge on AC, to 3 decimals | 84 Wh on 12 V / USB, to 3 decimals | Full sum, to 3 decimals | Nameplate |
|---|---|---|---|---|
| 1 | 400.370 | 107.333 | 507.704 | 508 Wh |
| 2 | 800.741 | 214.667 | 1,015.407 | 1,015 Wh |
1 day: 282 × 1.15 / 0.81 + 84 × 1.15 / 0.90 = 507.703703… → 508 Wh
400.370 + 107.333 = 507.704 Wh (from unrounded quotients). 800.741 + 214.667 = 1,015.407 Wh (from unrounded quotients).
Battery draw for that mixed day, before buffer and DoD: 84 + 282 / 0.90 = 397.333 Wh. Days = (label × 0.90) / 397.333. A 500 Wh label covers 1.133 days. A 1,000 Wh label covers 2.265 days. Those runtime days do not include the buffer. The buffered 508 Wh plan is 8 Wh over a 500 Wh label. This site’s small-class ceiling is 512 Wh, so 508 Wh is inside the class and above a 500 Wh label. 1,015 Wh is 15 Wh over a 1,000 Wh label and inside the ~1,000 Wh class (ceiling 1,152 Wh). The loaded camping day with a laptop is a different stack on weekend camping.
Overnight outage, no CPAP, no fridge
One night and two nights on extension cords from the station. No house fridge. That sticker day is home outage, and it does not fit either label here. No CPAP. Lamps are on AC outlets. The router and the phones stay on USB.
| Load | Basis | Wh | Path |
|---|---|---|---|
| Two GE Basic A19 lamps | The GE page prints wattage 8.5 W at 120 V, and “60 Watt replacement” as the old-bulb line. 8.5 W × 2 × 6 h. Six hours is this night, not GE’s 3 h/day cost example. The dollar line on that page is not used. | 102 | AC, η=0.90 |
| GL.iNet GL-MT3000 | Power consumption is printed as <8 W. Power input is Type-C, 5 V / 3 A. 5 × 3 = 15 W is the port rating, not the day. Ceiling: 8 W × 12 h. Twelve hours is this window. | 96 | USB, η=1.00 |
| Two phones | Same 20 W × 1 h × 2 ceiling as the camp day. | 40 | USB, η=1.00 |
| Night | USB 96 + 40 = 136. AC lamps 102. | 238 | Two passes |
USB pass: 136 × 1.15 / 0.90 = 173.778, which rounds to 174 Wh alone. AC pass: 102 × 1.15 / 0.81 = 144.815, which rounds to 145 Wh alone. Add the exact passes. 173.778 + 144.815 = 318.593 → 319 Wh. Two nights: 637.185 → 637 Wh. Do not double the rounded night. 319 × 2 = 638.
1 night: 136 × 1.15 / 0.90 + 102 × 1.15 / 0.81 = 173.778 + 144.815 = 318.593 → 319 Wh
2 nights: 637.185 → 637 Wh
Battery draw per night: 136 + 102 / 0.90 = 249.333 Wh. A 500 Wh label covers (500 × 0.90) / 249.333 = 1.805 nights (43.316 hours at that average). A 1,000 Wh label covers 3.610 nights (86.631 hours). The buffered 319 Wh plan fits a 500 Wh label. The buffered 637 Wh plan does not. Two nights of this stack are where 1,000 Wh is the floor.
If the router and the phones move onto AC bricks, the whole 238 Wh uses η=0.90. One night is 337.901 → 338 Wh. Two nights are 675.802 → 676 Wh. Same decision: 500 covers one night, 1,000 covers two. Runtime on that all-AC path is 405 / 238 = 1.702 nights and 810 / 238 = 3.403 nights. Do not use the mixed 1.805 for the all-AC path.
Van day: laptop and one fan
Engine off. Solar = 0. No fridge. The fridge day is van daily Wh. This row is the laptop and one fan, which is the case a 500 Wh label still covers.
| Load | Basis | Wh | Path |
|---|---|---|---|
| MacBook Air 13-inch (M3), one recharge | 52.6 Wh battery. One recharge is this day. 52.6 Wh is energy stored in the pack. Charger loss is not on that page, so this row is a floor. The included 30 W USB-C adapter (8-core GPU model) is a watts rating, not 30 W × hours. | 52.6 | USB-C, η=1.00 |
| One Caframo Sirocco II, high | 0.35 A is the 12 V high column, not the 24 V column. 0.35 × 12 = 4.2 W. Timer steps on the sheet are 3, 6, 9, and 12 h. This day uses 6 h (25.2 Wh) and the long step, 12 h (50.4 Wh). | 25.2 or 50.4 | 12 V, η=1.00 |
| Day | Wh at the loads | Steps (÷ 1.00, × 1.15, ÷ 0.90) | Exact | Nameplate |
|---|---|---|---|---|
| Fan on the 6 h timer | 52.6 + 25.2 = 77.8 | 77.800 → 89.470 → nameplate | 99.411 | 99 Wh |
| Fan on the 12 h timer | 52.6 + 50.4 = 103 | 103.000 → 118.450 → nameplate | 131.611 | 132 Wh |
77.8 × 1.15 / 0.90 = 99.411 → 99 Wh
103 × 1.15 / 0.90 = 131.611 → 132 Wh
A 500 Wh label delivers 450 Wh on 12 V. 450 / 77.8 = 5.784 days (138.817 hours). 450 / 103 = 4.369 days (104.854 hours). A 1,000 Wh label is 11.568 days at 77.8 Wh and 8.738 days at 103 Wh. Both buffered plans, 99 Wh and 132 Wh, sit under a 500 Wh label. This van day is not the reason to step from 500 Wh to 1,000 Wh.
The 30 W adapter plugged into an AC outlet puts the recharge on η=0.90, and 52.6 Wh is still a floor. That floor is 52.6 × 1.15 / 0.81 = 74.679 → 75 Wh. The 6 h fan stays on 12 V: 25.2 × 1.15 / 0.90 = 32.200 → 32 Wh. Exact sum 106.879 → 107 Wh. Still under a 500 Wh label. Math.round of the exact 32.2 is 32. In JavaScript the same multiply lands on 32.199999999999996, and Math.round of that is also 32.
A small microwave and a coffee maker
Stored energy can pass while the inverter’s continuous line fails. Surge is a brief start. A magnetron cook and a heater brew last minutes. The peak line is not those minutes. No surge multiple is invented here. No scope trace.
The Comfee manual for AM720C2RA-R, AM720C2RA-A, and AM720C2RA-G prints 120 V, 60 Hz, rated microwave input 1,050 W, rated microwave output 700 W, capacity 0.7 cu ft. 700 W is cooking output. The wall draw on that sheet is 1,050 W. The sheet does not print a power factor, so this page does not invent one. Six minutes is this page’s reheat window, not a cook on the sheet. The manual’s own maximum time is longer.
1,050 W × (6/60) h = 105 Wh
105 × 1.15 / 0.81 = 149.074 → 149 Wh
A 500 Wh label delivers 405 Wh on AC, which is 405 / 105 = 3.857 of those windows. A 1,000 Wh label delivers 810 Wh, 7.714 windows. Both labels store one cook. Neither number turns the oven on.
The Hamilton Beach use-and-care PDF for models 48350 and 48351 prints 120 V ~ 60 Hz 900 W on the electrical-characteristics line. Ten minutes is this page’s brew window. The PDF does not print a brew time.
900 W × (10/60) h = 150 Wh
150 × 1.15 / 0.81 = 212.963 → 213 Wh
405 / 150 = 2.700 windows on a 500 Wh label. 810 / 150 = 5.400 windows on a 1,000 Wh label. The energy fits. 900 W is a continuous heater for those ten minutes, not a start surge.
Use cords rated for the load. Don't daisy-chain extension cords or power strips. Do not backfeed a breaker panel. The oven plugs into the station, not into a house circuit through the panel.
Inverter watts and charge input are not the Wh label
Two manuals, read 2026-10-23, show why a ~500 Wh class and a ~1,000 Wh class are not “twice the everything.” The round 500 and 1,000 labels above are the energy comparison. These sheets are the watts and the input ceilings. They are not a ranking.
| Line | RIVER 2 Max manual | DELTA 2 manual |
|---|---|---|
| Printed capacity | 512 Wh (20 Ah, 25.6 V). Not a 500 Wh label. | 1,024 Wh, 51.2 V. Not a 1,000 Wh label. |
| Cell chemistry / cycle life | LFP, 3,000 cycles to 80%+ capacity. | LFP, 3,000 cycles to 80%+ capacity. |
| AC output | Pure sine, 500 W total (1,000 W peak), 120 V. The peak cell prints no seconds. | Pure sine, 1,800 W total (surge 2,700 W), 120 V. The surge cell prints no seconds. |
| X-Boost | Devices rated up to 1,000 W. Not for appliances with voltage protection. Suitable for heating and motor-driven devices; the manual says to test. The FAQ still says keep the sum under the rated power. X-Boost works by lowering output voltage below 120 V. Our sizing rule: voltage-reduction lift modes are for resistive heating loads only. Reduced voltage can stall or overheat motor and compressor loads. Not a surge rating. Do not size on it. | 2,200 W on the spec line. The manual enables it when output exceeds rated power, says it is more suitable for heating devices, and says it is not for every appliance. X-Boost works by lowering output voltage below 120 V. Our sizing rule: voltage-reduction lift modes are for resistive heating loads only. Reduced voltage can stall or overheat motor and compressor loads. Not a surge rating. Do not size on it. |
| AC charge | X-Stream 660 W max, and “fully charged in 1 hour.” 512 Wh / 1 h = 512 W, which sits under 660 W. Do not turn 660 W × 1 h into a 660 Wh battery. | X-Stream 1,200 W max, 10 A, 100–120 V. The manual does not print a one-hour full-charge claim on that line. |
| Solar input | 11–50 V, 13 A, 220 W max. Keep panel voltage under 50 V. 220 W is a ceiling, not a day’s harvest. | 11–60 V, 15 A max, 500 W max. A ceiling, not a harvest. See solar vs battery. |
| Car charge input | 12 V / 24 V, 8 A, 100 W max. | 12 V / 24 V battery, default 8 A. The spec line does not print a watt. This page does not invent one. |
| 12 V output | 12.6 V, 10 A / 3 A / 3 A, 126 W max. 126 W is the printed total, not 126 W from each of those currents. That ceiling is not the fridge’s 11.75 W average. | 12.6 V, 10 A, 126 W max, shared with the DC5521 ports. |
| Weight, as printed | Approximately 6.1 kg (13.4 lb). | Approximately 12 kg (27 lb). |
On those printed lines, the 1,050 W microwave is over the RIVER 2 Max rated 500 W, over the 1,000 W peak, and over the X-Boost ceiling of 1,000 W. It is under the DELTA 2 continuous 1,800 W, so that sheet’s continuous line covers this oven alone. The 2,700 W surge is not what covers a six-minute cook. The 900 W coffee maker is over the 500 W rated line. It is under the 1,000 W peak number and under the X-Boost ceiling, and the brew is still minutes. The manual’s “test a heating device” sentence and its “stay under rated power” sentence are both on the sheet. This page does not call 900 W a pass on the RIVER 2 Max. DELTA 2’s 1,800 W continuous line covers 900 W without X-Boost.
Delivered energy on the printed labels, same factors, rounded once: 512 × 0.90 = 460.8 → 461 Wh on 12 V, and 512 × 0.81 = 414.72 → 415 Wh on AC. 1,024 × 0.90 = 921.6 → 922 Wh on 12 V, and 1,024 × 0.81 = 829.44 → 829 Wh on AC. The 829 Wh AC figure is the same product already on EcoFlow vs Jackery vs Bluetti. Do not shop 415 Wh as if it were the round label’s 405 Wh.
A 512 Wh sheet covers the one-day camp plan (468 Wh) and the AC-fridge split (508 Wh), because 512 ≥ 508. It does not cover two camp days (935 Wh) or two outage nights (637 Wh). A 1,024 Wh sheet covers the two-day AC-fridge split (1,015 Wh). A round 1,000 Wh label does not.
Weight, and price only as a listing
The RIVER 2 Max manual prints about 6.1 kg. The DELTA 2 manual prints about 12 kg. On these two sheets, about twice the watt-hours comes with about twice the mass. Both weights say “approximately,” so this page does not divide Wh by kilograms. Neither manual prints a price. Price per watt-hour is whatever the current listing says. A lighter station is not automatically the better buy, and a heavier one is not automatically the right inverter.
Where 500 Wh is enough
“Covers” means the round label is at least the buffered nameplate. The heating rows store the energy and still have to pass the watts check above.
| Buffered plan | Nameplate | 500 Wh label | 1,000 Wh label |
|---|---|---|---|
| Camp, 366 Wh, 1 day, 12 V | 468 Wh | Covers | Covers |
| Camp, 366 Wh, 2 days, 12 V, solar = 0 | 935 Wh | Short. 1,000 Wh is the floor. | Covers |
| Camp, fridge on AC, 1 day | 508 Wh | Short by 8 Wh. Class ceiling is 512. | Covers |
| Camp, fridge on AC, 2 days | 1,015 Wh | Short | Short by 15 Wh. Class ceiling is 1,152. A 1,024 Wh sheet covers it. |
| Outage night, USB plus AC lamps, 1 night | 319 Wh | Covers | Covers |
| Outage, 2 nights, solar = 0 | 637 Wh | Short. 1,000 Wh is the floor. | Covers |
| Outage, all on AC, 1 night | 338 Wh | Covers | Covers |
| Outage, all on AC, 2 nights | 676 Wh | Short | Covers |
| Van, laptop + fan 6 h | 99 Wh | Covers | Covers |
| Van, laptop + fan 12 h | 132 Wh | Covers | Covers |
| One 6 min microwave window | 149 Wh | Energy covers. 1,050 W does not run on a 500 W rated line. | Energy covers. Watts depend on that station’s continuous line, not on the 1,000 Wh label. |
| One 10 min coffee window | 213 Wh | Energy covers. 900 W is over a 500 W rated line. | Energy covers. A 1,800 W continuous line covers 900 W. The label alone does not. |
500 Wh is enough for one 12 V camp day of this fridge stack, for one CPAP-free night of this lamp-and-router stack, and for the laptop-and-fan van day. 1,000 Wh is the floor for two of those camp days and for two of those nights, with solar at zero. A microwave or a drip coffee maker is a watts problem. Buying the next watt-hour class does not fix a 500 W inverter.
Related: surge traps · 1,000 vs 2,000 Wh · weekend camping · home outage · van daily Wh · under ~500 Wh · ~1,000 Wh class
Wh calculator — one η per pass. 12 V and USB: set inverter efficiency to 1.00. AC outlets: leave η at 0.90. nameplate = (Wh/day × days × 1.15) / (0.90 × η).
Where to check pricing
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