To all our international friends living in or visiting Japan: Welcome!
I hope you are enjoying the amazing food culture here. Convenience store (Konbini) bentos and high-quality frozen foods are lifesavers, aren’t they?
However, as you pick up a delicious frozen pasta or gratin, you might have noticed something frustrating on the back of the package.
“Cooking Time: 500W – 5 min 00 sec / 600W – 4 min 10 sec”
You might be thinking: “Wait, my microwave at home has a 1000W or 800W mode! Do I really have to wait 5 whole minutes? Can’t I just blast it at full power?”
As a local Japanese resident, I totally agree with you. It is too slow.
Why is it always “500W”?
In Japan, the standard display for heating instructions has traditionally been 500W or 600W to accommodate older appliance models. Even though many modern Japanese microwaves (like the ones from Panasonic or Toshiba) have “800W” or “1000W” buttons, the food manufacturers still prioritize the lower settings for safety and uniformity.
But for busy people, those extra minutes of waiting are painful.
Why I Built a Tool to Solve This
Let me introduce myself. My name is Yuki, and I am a Japanese IT Strategist. Currently, I am taking a sabbatical leave to attend a vocational school for AI and programming.
But more importantly, I am a father of three children (3-year-old twins and a newborn baby!).
Life with three kids is chaos. When my twins are crying for lunch, or when I finally have a 10-minute break between baby care and coding studies, I cannot afford to wait 5 minutes for a frozen meal to heat up.
I wanted to use my microwave’s “1000W” mode to cut the cooking time in half. But calculating the conversion in my head (e.g., “If 500W is 5 minutes, then 1000W is…”) is risky. If I guess wrong, the food explodes inside the oven.
So, as part of my programming studies, I decided to build a solution.

“Microwave Time Saver” (Renchin Jitan Keisan)
I developed a simple app called “Microwave Time Saver”. It instantly converts the package instructions (500W/600W) into the optimal time for your microwave’s wattage (e.g., 700W, 800W, 1000W, 1200W, etc.).
How it works:
- Select the wattage written on the food package (e.g., 500W).
- Enter the time written on the package (e.g., 3:00).
- Select YOUR microwave’s wattage (e.g., 1000W).
- Result: The app instantly tells you the perfect heating time (e.g., “1:30”)!
It is designed to be simple, cute, and super fast.
Try it for Free!
I released this tool as a Web App (PWA) and an Android App. It supports English, so please give it a try.
Web Version (No install required, works on iPhone/PC):
Android App (Google Play Store):
For all the busy expats, parents, and hungry students out there—let’s stop wasting time in front of the microwave and enjoy Japan’s food faster!
If you have any feedback, feel free to contact me. Enjoy your “Time Saved” life!


コメント