Kiln Firing Schedule Time Calculator

A kiln schedule calculator adds up how long your firing will take: each segment’s time is the temperature change divided by the ramp rate, plus its hold. Enter your own segments in °F or °C below to get firing time, a per-segment breakdown, the date and time the firing ends and an optional cooling-end estimate.

How to use the kiln schedule calculator

1. Choose °F or °C. Enter every temperature and every ramp rate in that same unit.
2. Type the starting temperature — usually the temperature of the kiln when you press start.
3. For each segment of your controller program, enter the target temperature, the ramp rate in degrees per hour and the hold in minutes (leave hold blank for none). Use + Add segment for more rows, up to 12. Removing a row renumbers the rest automatically.
4. Optionally add the hours of natural (unpowered) cooling your kiln needs before you can open it.
5. Check the start date and time. It defaults to right now in your local time; change it if you plan to start the kiln later. If you pick a time that your clock skips at the spring daylight-saving change, the tool asks you to choose another time.
6. Press Calculate firing time. The result shows the total, the firing end and, if you entered cooling hours, a cooling-end estimate. The segment table lists each segment’s rate, ramp duration, hold, segment duration and running elapsed time, plus the clock time each segment ends when a start time is set.
7. Press Copy summary to copy the totals, the segment breakdown and the finish estimates as plain text, ready to paste into a firing log.

The tool does not suggest rates, holds or cone temperatures. Copy the schedule you already use, or the one your kiln manufacturer or clay and glaze supplier recommends, and let the calculator handle the arithmetic.

How kiln firing time is calculated

A programmable kiln controller runs a schedule as a list of segments. Each segment ramps from the previous temperature to a target at a set rate, then optionally holds (soaks) there. The time for one segment is:

Segment hours = |target − previous temperature| ÷ rate + hold minutes ÷ 60

The absolute value means a controlled cooling segment (a target lower than the previous one) is timed the same way, and a segment whose target equals the previous temperature is a pure hold. Firing time is the sum of all segments, and the running total after each segment is its elapsed time. Each segment’s end clock time is the start plus that exact elapsed time, rounded to the minute only for display. Any segment shorter than one minute is shown as “<1 min” but is still counted exactly.

Here is a worked example with an arbitrary three-segment program in °F, starting at 70 °F at 06:00. These numbers only illustrate the math and are not a recommended schedule.

Working in Celsius, converting rates and planning the finish time

The calculation is identical in either unit as long as you do not mix them. Temperatures convert with °C = (°F − 32) × 5/9 and °F = °C × 9/5 + 32. Ramp rates are temperature differences, so the 32-degree offset drops out: 1 °C per hour equals 1.8 °F per hour. A 100 °C/h rate is 180 °F/h, and a 300 °F/h rate is about 166.7 °C/h.

Long firings often run past midnight or over several days, so each finish shows the full date and a “+1 day” or “+2 days” marker. Because the tool adds real elapsed hours, a firing that runs through a daylight-saving clock change still lasts the same number of hours; only the clock reading shifts. For example, a 4-hour firing started at midnight on a spring-forward night ends at 05:00 on the new clock. A start time inside the skipped hour does not exist, so the calculator rejects it instead of silently moving it.

The firing end tells you when the controller program finishes; the per-segment end times tell you when to be around for a particular stage. The result assumes your kiln actually keeps up with every programmed rate; near the top of a firing, a heavily loaded kiln or older elements may heat more slowly than programmed, so the real firing can run longer. Natural cooling time varies with kiln size, insulation and load, so the tool does not estimate it — enter your own figure from your firing log.

Methodology & sources

Every rate, hold, temperature and cooling time is supplied by you; the calculator contains no reference schedules, default rates or cooling presets. It applies the segment formula above, sums the segments, and adds the exact cumulative elapsed time to your local start date and time for each segment end and the firing end. Peak temperature is converted between units with the standard Fahrenheit–Celsius formulas, checked November 2026.

• Wikipedia — Fahrenheit: conversion formulas °C = (°F − 32) × 5/9 and °F = °C × 9/5 + 32, from which the 1.8 rate factor follows.

Last updated: November 2026

FAQ

How do you calculate how long a kiln firing segment takes?

Divide the temperature change by the ramp rate, then add the hold time. For example, going from 70 °F to 1000 °F at 300 °F per hour takes 930 ÷ 300 = 3.1 hours, plus any hold.

Does the calculator work in Celsius?

Yes. Choose °F or °C and enter every temperature and rate in that unit. The peak temperature is also shown converted to the other unit using °C = (°F − 32) × 5/9.

Can I add a controlled cooling segment?

Yes. A segment whose target is lower than the previous temperature is treated as a controlled cool, and its time is the temperature drop divided by the rate. Unpowered natural cooling can be added separately as cooling hours.

Why does the calculator not suggest a firing schedule?

Safe rates and holds depend on your clay, glaze, kiln and the manufacturer’s instructions, so this tool only does the arithmetic on the schedule you enter. Use your kiln or clay supplier’s recommended schedule.

How do I convert a ramp rate between °F and °C per hour?

Multiply a °C/h rate by 1.8 to get °F/h, or divide a °F/h rate by 1.8 to get °C/h. A rate is a temperature difference, so the +32 offset does not apply.

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