This converter turns light-years into inches instantly, using the exact factor 1 light-year = 3.724697036e+17 inches. Type any number and the result updates as you go — nothing is sent to a server, so the arithmetic happens entirely in your browser.
The distance light covers in one Julian year — about 9.46 trillion kilometres. Exactly 25.4 millimetres since the 1959 international yard agreement.
Because the relationship is a simple proportion, one multiplication does the whole job. The table further down gives pre-computed values for the amounts people look up most often, and the result panel also reports the reverse conversion so you can check the figure both ways.
The formula
light-years- The amount you are converting, measured in light-years
3.724697036e+17- The exact number of inches in one light-year
inches- The converted result
How it works, step by step
- Enter the number of light-years you want to convert.
- The value is multiplied by 3.724697036e+17, the exact conversion factor.
- The result is displayed in inches, rounded for readability.
- The unrounded value and the reverse conversion appear underneath so you can verify it.
Worked examples
Converting 5 light-years
Multiply 5 by 3.724697e+17. That gives 1.8623e+18 inches. A quick sanity check: one light-year is larger than one inch, so the number should get bigger — and it does.
Converting 72 light-years
72 × 3.724697e+17 = 2.6818e+19 inches. Working backwards, 2.6818e+19 ÷ 3.724697e+17 returns 72 light-years, which confirms the factor is applied the right way round.
How to read your score
Frequently asked questions
How many inches are in one light-year?
Exactly 3.724697036e+17. Every conversion on this page is that single number multiplied by your input, so the result carries no rounding error beyond what is shown.
What is the formula to convert light-years to inches?
Inches = light-years × 3.724697036e+17. To reverse it, divide instead: light-years = inches ÷ 3.724697036e+17, which is the same as multiplying by 2.684782118e-18.
Is the light-year bigger than the inch?
Yes. One light-year equals 3.7247e+17 inches, so it is the larger unit.
Why does my answer differ slightly from other light-years to inches converters?
Most differences come from rounding the factor too early. This tool keeps full double precision through the calculation and only rounds at the final display step, and it also shows the unrounded value so you can see exactly where any difference appears.
What is a light-year?
The distance light covers in one Julian year — about 9.46 trillion kilometres.
What is a inch?
Exactly 25.4 millimetres since the 1959 international yard agreement.
Light-Years to inches reference table
| Light-Years | Inches |
|---|---|
| 0.5 ly | 1.8623e+17 in |
| 1 ly | 3.7247e+17 in |
| 2 ly | 7.4494e+17 in |
| 3 ly | 1.1174e+18 in |
| 5 ly | 1.8623e+18 in |
| 10 ly | 3.7247e+18 in |
| 15 ly | 5.5870e+18 in |
| 20 ly | 7.4494e+18 in |
| 25 ly | 9.3117e+18 in |
| 50 ly | 1.8623e+19 in |
| 75 ly | 2.7935e+19 in |
| 100 ly | 3.7247e+19 in |
| 250 ly | 9.3117e+19 in |
| 500 ly | 1.8623e+20 in |
| 1000 ly | 3.7247e+20 in |
Exact factor: 1 light-year = 3.724697036e+17 inches. Values rounded for display.