Age by Serial

Equipment Remaining Life Calculator

Choose the equipment and enter its build year to see its age and the years left in a typical lifespan range.

Last updated:

Four digits, 1950 or later. A decoder on this site can give you the year from the serial number.

Optional. Leave blank for the current year (UTC).

Age
years
Distance from range ends
toyears

Planning figures only. The ranges come from one source, InterNACHI's Standard Estimated Life Expectancy Chart. They are not failure dates, and not a repair or replace verdict.

How this is calculated

  1. Age = as-of year minus build year, a difference in calendar years. Only the year is known, so the age can be off by one.
  2. Distance from range ends, low end = the range's minimum minus the age, never below 0. High end = the range's maximum minus the age, never below 0.
  3. Status: Below range if the age is under the minimum, Within range from the minimum to the maximum inclusive, Beyond range if over the maximum.

Worked example: a furnace built in 2005, checked in 2026, is 21 years old. With a range of 15 to 25 years the age is already past the low end (shown as 0) and 4 years short of the high end, and the status is within range. This describes where the age sits against a published range; it is not a prediction of service life.

Typical lifespan ranges used by this calculator (InterNACHI)
EquipmentLow (years)High (years)
Furnace1525
Heat pump1015
Central air conditioner715
Conventional tank water heater612

Where the figures come from

  1. Standard Estimated Life Expectancy Chart, InterNACHI (International Association of Certified Home Inspectors). Accessed 9 November 2026.

All four ranges come from this one source. We left out tankless water heaters and boilers because we do not have an agreed source for them. Real lifespans depend on water quality, maintenance, climate and use.

Related decoders and guides

  • How long does a furnace lastInterNACHI's chart gives furnaces 15 to 25 years. Here is what that range does and does not tell you, how to find your furnace's age, and the signs it is wearing out.
  • How long water heaters lastSources give 6 to 12, 8 to 12 and 10 to 15 years for a tank water heater. Here is how to find your unit's age, the signs it is failing, and what to do about a leak.
  • How long does an air conditioner lastInterNACHI's chart gives a central air conditioner 7 to 15 years and a heat pump 10 to 15 years. Here is how to read those ranges, check your unit's age and spot signs of wear.
  • Appliance Age Finder: Water Heater, Furnace and AC Age by Serial NumberPick the brand, type the serial number from the label, and get the build date and age. Brands we cannot check are never guessed.
  • Bradford White decoderType the serial number from the rating plate to get the build month, build year and age, with the rule shown below.