What is a ballistic coefficient (BC)?

The G1 ballistic coefficient is a dimensionless number that describes how efficiently a bullet retains velocity against air drag. Higher BC (e.g. 0.50) means less drop and wind drift at long range. You will find it on the bullet or ammo packaging, or in the manufacturer's load data.

Why does the bullet start below the line of sight close up?

The scope sits 1–2 inches above the bore. At the muzzle the bullet is physically below the scope's optical line of sight. The bore is angled slightly upward so the bullet crosses the line of sight at a close distance (typically 25–50 yd), rises above it, then drops back through it at the zero range and continues to fall.

What is the difference between a 100-yard zero and a 200-yard zero?

With a 100-yard zero your bullet hits exactly at point of aim at 100 yd but drops more by 200–300 yd. A 200-yard zero keeps the bullet within about ±3 in from 0–250 yd (useful for deer-sized vital zones), reducing holdover needed at typical hunting distances.

How accurate is this calculator?

This tool uses a Pejsa-style numerical integration of the G1 drag model with a standard atmosphere (59 °F, sea level, 29.92 inHg). Results are accurate within 1–2 inches at 300 yd under standard conditions. Altitude, temperature, and wind are not modeled; for precision long-range work use a dedicated solver with an atmosphere input.

What is a typical ballistic coefficient for common rifle cartridges?

55-grain .223 Rem FMJ: ~0.24. 150-grain .308 Win FMJBT: ~0.41. 180-grain .30-06 SPBT: ~0.44. 140-grain 6.5 Creedmoor ELD-M: ~0.61. Heavier, longer, boat-tail bullets have higher BCs.

Rifle Zero Calculator

Name: Rifle Zero Calculator
Availability: InStock
Author: Nham Vu

Enter your zero distance, sight height, muzzle velocity, and ballistic coefficient to see where your bullet hits at any range.

Rifle & Load Parameters

Unit System

Zero Range (yards)

Sight Height Above Bore (inches)

Muzzle Velocity (fps)

G1 Ballistic Coefficient (e.g. 0.41)

Max Range in Table (yards)

Point of Impact vs. Point of Aim

Range	Velocity	POI	Energy

Set your parameters and click Calculate to see the trajectory table.

Summary

Enter your zero distance, sight height, muzzle velocity, and ballistic coefficient to see where your bullet hits at any range.

How it works

Enter your zero range — the distance at which your rifle is currently sighted in.
Enter the sight height above bore in inches (typically 1.5 in for standard scope mounts).
Enter muzzle velocity in feet per second (fps) from your ammo box.
Enter the G1 ballistic coefficient (BC) of your bullet, found on the ammo or bullet box.
Click Calculate to see a table of point of impact at each distance from 0 to 500 yards.
Positive values mean the bullet is above the line of sight; negative values mean it is below.

Use cases

Choosing between a 100-yard and 200-yard zero for deer hunting.
Estimating holdover or dial-up needed at 300, 400, or 500 yards.
Comparing trajectories of different loads with different BCs.
Verifying that your rifle scope adjustments match expected POI shift.
Teaching new shooters about bullet drop and ballistic coefficient.
Planning shots at extended range without a phone ballistic app.

Frequently Asked Questions

Last updated: 2026-07-01 · Reviewed by Nham Vu