This free compost temperature tracker helps you log daily pile temperatures in the browser and chart the heat-up, hot and cooling phases. Temperature is the simplest honest signal a pile gives you: a rising line means microbes are working, and a flat cold line means the pile needs air, water, or more greens. It runs fully in your browser, so nothing you type is sent to a server. You need no account and no sign-up to use it.
Without a thermometer, gardeners guess at the pile and often guess wrong. A chart shows the heat peak, the length of the hot phase, and the cooling curve, so you know when weed seeds have likely died and when the compost is safe to use.
To use the tool, fill in the boxes on screen and press the calculate button. You can change any number and calculate again as often as you like. The result updates at once, so you can test different plans side by side and see which one fits your garden best.
For example, log 20 degrees on day one, 45 degrees on day three, and 62 degrees on day five. The chart climbs through the heating phase into the hot phase, and the tool labels the latest reading as hot. When the line later falls below 40 degrees for several days, the pile is cooling and nearing the maturing stage.
Check temperature at the same time each day, ideally in the morning before the sun warms the bin walls. A reading taken at noon in summer can look hotter than the pile really is, and a steady morning routine keeps the chart honest across seasons.
Tip: Push the thermometer into the centre of the pile, not near the wall. The centre is the hottest part and the truest reading.
Tip: Log every day for the first two weeks. The early climb tells you more than a single reading taken a month later.
Tip: Keep the chart after the pile finishes. Next year you can compare piles and see which mix heated fastest.
The most common mistake is measuring only the surface. The top few centimetres cool overnight and can read 20 degrees colder than the centre, which makes a healthy hot pile look dead and tempts you to rebuild it for no reason.
Common question: What temperature kills weed seeds? Sustained heat above 55 degrees for several days greatly reduces most weed seeds, which is why the hot phase matters.
Common question: My pile never passes 30 degrees. What now? Add more greens, add water until it feels like a wrung sponge, and turn it. A cold pile usually lacks nitrogen, air, or moisture.
Common question: Is the chart saved? Readings live in this page session, so keep the tab open or copy the numbers into a notebook for a long pile.
Serious home composters, allotment holders, and school garden teachers use temperature logs to teach how microbes work. It also helps beginners who want proof that their first pile is really heating up.
Keep a note of your pile dates and results through the season. After a few months you will see which mixes heated fastest and which plans finished on time. That record is worth more than any guess, because it comes from your own garden and your own waste.
Before you build the pile, read your plan once as if you were doing it tomorrow. Do you have the browns, the space, and the dates clear? If anything looks unclear, fix that line before you start. A plan that needs no guesswork works far better than a bigger plan that confuses you.
This tool is free to use as often as you like. Bookmark it and come back whenever you start a new pile or plan a harvest. A clear plan helps you compost with less smell, fewer flies, and more finished compost for your beds.
Remember that every result here is an estimate for home composting, not professional advice. Your local climate, your waste mix, and your bin type all shape the real result, so use the tool as a starting point and adjust it to your own garden.