Generation Calculator

Enter a birth year to find out which generation you belong to — Boomer, Gen X, Millennial, Gen Z, or Alpha. Free, instant, no signup.

Birth year

How to use the Generation Calculator

Enter your values. Fill in the fields with your numbers.
Calculate. Press Calculate to run the generation calculator.
Use the result. Copy the result or try a related tool next.

Why use our Generation Calculator

Instant results. Enter your figures and the generation calculator returns an answer in seconds.

Free & private. Runs in your browser — no signup, and nothing is sent to a server.

Accurate. Uses standard formulas so you can rely on the numbers.

Free to use — premium coming soon

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About the Generation Calculator

The Generation Calculator estimates how many generations separate two people in a family line using the gap between their birth years. You enter an ancestor's birth year and a descendant's birth year (or simply a span of years), and the tool divides that span by an average generation length to return an approximate number of generations. It is built for genealogists, family historians, and anyone reconstructing a family tree who has a birth year but not a clear list of the parent-child links connecting two relatives.

Reach for this calculator when you know two dates but not the lineage between them, such as a great-great-grandparent born in 1850 and yourself born in 1990. A 140-year gap divided by a 30-year generation length suggests roughly four to five generations, which tells you how many parent-child steps to look for in records. It is equally handy in reverse: pick a number of generations and a starting year to estimate the era an ancestor likely lived in, giving you a date range to focus census and parish searches on.

Mechanically the tool applies generations = year gap / average generation length. Genealogical convention long used 25 years per generation, but modern pedigree and DNA research points higher. The ISOGG and studies summarized by genetic genealogists suggest about 30 years overall, with roughly 33 years for male lines and 29 years for female lines. Many calculators let you switch between 25, 30, or a custom value so you can match your own family's pattern, since age at parenthood varies widely by era, region, and circumstance.

Treat every result as an estimate, not a fact. Because real families have parents of every age, the count can be off by a generation either way, especially across long spans or lines with very young or very late parents. The honest use is as a planning aid that narrows where to search, after which you confirm each link with actual records. This calculator runs entirely in your browser: the birth years you type are never uploaded or stored, so your family details stay private on your device.

Frequently asked questions

How does the Generation Calculator estimate the number of generations?

It subtracts the older birth year from the younger one and divides that gap by an average generation length. For example, a 120-year gap at 30 years per generation works out to about four generations.

How many years is one generation?

There is no fixed number, but modern research suggests around 30 years on average, often broken down as roughly 33 years for father-to-child lines and 29 years for mother-to-child lines. The old genealogical rule of thumb was 25 years, which most researchers now consider too short.

Should I use 25 or 30 years per generation?

Use about 30 years for general estimates, or 33 for a male line and 29 for a female line. Choose 25 only if you have evidence your family had children unusually young, and use a custom value when you can calculate the actual average from known births.

How accurate is the result?

It is a rough estimate that can be off by a generation in either direction, since parents are not all the same age. Use it to narrow your search to a likely range of generations, then confirm each parent-child link with real records.

Can it tell me how many ancestors I have in a generation?

The number of direct ancestors doubles each generation back: 2 parents, 4 grandparents, 8 great-grandparents, following 2 to the power of n. Ten generations back gives 2,046 ancestors in total across all those generations, though shared ancestors mean the real count is lower.

From our blog

Ohm's Law in Practice: Solving Real Circuits With Two Known Values

By the Super Simple Digital Tools Team · Updated June 2026

Ohm's Law is the single most useful equation in basic electronics because it ties together the three quantities you can actually measure on a workbench: voltage across a component, current through it, and the resistance that opposes that current. The relationship V = I x R means that for a fixed resistance, doubling the voltage doubles the current, and for a fixed voltage, raising the resistance lowers the current. Once you internalise that proportionality, a lot of circuit behaviour stops being mysterious and becomes predictable arithmetic.

Power is the fourth piece of the puzzle, and it comes from Watt's Law, P = V x I. Combine the two laws and you get a wheel of twelve formulas, three for each quantity, that lets you start from whichever pair of values you happen to know. Know voltage and current? You can get resistance and power. Know power and resistance? You can recover voltage and current with P = V squared / R and I = the square root of P / R. The calculator simply selects the right member of that wheel for the inputs you give it.

A classic worked example is an LED. Suppose you have a 9 V supply and an LED that should run at 20 mA with about 2 V across it. The resistor must drop the remaining 7 V at 0.02 A, so R = V / I = 7 / 0.02 = 350 ohms, and you would round up to a standard 360 or 390 ohm part. Checking the power, P = V x I = 7 x 0.02 = 0.14 W, which tells you a common quarter-watt resistor is fine. That two-step check, resistance then wattage, prevents both a burned-out LED and a scorched resistor.

It pays to respect the limits of the law. Ohm's Law describes ohmic materials, where the current-voltage line is straight. Real diodes, LEDs, transistors, lamps with hot filaments and many sensors are non-ohmic, so you can't pin them to one resistance value across their whole operating range. For alternating current you also need impedance instead of plain resistance, because capacitance and inductance shift current and voltage out of step. The calculator is built for the common DC, resistive case, which still covers the vast majority of everyday hobby and learning circuits.

Used well, the tool is more than a homework helper, it is a debugging instrument. If you measure a circuit and the readings don't match what Ohm's Law predicts, something is wrong: a wrong resistor value, a bad connection, a sagging supply, or a component operating outside its linear range. Plug in the two values you trust most, compare the predicted third against your meter, and the discrepancy points you straight at the fault. That habit of cross-checking measured against calculated is what separates guessing from genuine troubleshooting.

Always convert to base units first: amps not milliamps, ohms not kilo-ohms, watts not milliwatts, or your answer will be off by powers of ten.
After finding resistance, immediately check the power result and pick a component rated at least double that wattage for a safety margin.
When solving for current from power and resistance, remember the result uses a square root (I = root of P / R), so it isn't a simple division.
Use the calculator as a sanity check on meter readings: enter the two values you measured most reliably and compare the predicted third to spot wiring or component faults.

Read the full guide →

Tool by the Super Simple Digital Tools Team. Reviewed by our editorial team. Free to use, no signup required.