Conversion chart

1000W to 900W microwave time chart.

Use this page when food instructions are written for a 1000 watt microwave but your microwave is rated at 900 watts. The chart uses exact-second conversion so the math stays transparent.

1000W to 900W formula

Multiply the original cooking time by 1000 and divide by 900. If the converted time looks unusual, use the live calculator below to check your exact minutes and seconds.

Adjusted Time = Original Time × 1000 ÷ 900

Quick reference table

1000W instructions converted for a 900W microwave, using exact-second conversion.
Original time Converted time Difference
0:30 0:33 0:03 longer
0:45 0:50 0:05 longer
1:00 1:07 0:07 longer
1:15 1:23 0:08 longer
1:30 1:40 0:10 longer
2:00 2:13 0:13 longer
2:30 2:47 0:17 longer
3:00 3:20 0:20 longer
3:30 3:53 0:23 longer
4:00 4:27 0:27 longer
5:00 5:33 0:33 longer
6:00 6:40 0:40 longer
7:00 7:47 0:47 longer
8:00 8:53 0:53 longer
10:00 11:07 1:07 longer
12:00 13:20 1:20 longer
15:00 16:40 1:40 longer
20:00 22:13 2:13 longer

Calculator for custom times

Enter the exact package time if it is not shown in the chart.

Original cooking time

Adjusted cooking time

0:00

Enter a wattage pair and cooking time to calculate the estimate.

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