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.

Is a 25 yard zero the same as a 100 yard zero?

No. The bullet crosses the line of sight twice, once on the way up and again on the way down. A 25 yd zero for a typical .308 load is on again near 225 yd and about 2.7 in high at 100 yd, so it is not a 100 yd zero. To be zeroed at 100 yd, sight in at 25 yd so the group hits about 0.6–0.8 in low (this tool gives the exact offset for your load), then confirm at 100 yd.

How many clicks do I need to move my group?

One MOA is 1.047 in at 100 yd, so clicks = offset in inches ÷ (1.047 × distance ÷ 100) ÷ click value. A group 2 in low at 100 yd needs 1.91 MOA, which is 8 clicks UP on a ¼ MOA scope. One MIL is 3.6 in at 100 yd (10 cm at 100 m). At 25 yd every click moves impact a quarter as much, so you need four times as many clicks.

What are near zero and far zero?

The bore points slightly up, so the bullet first rises through the line of sight (near zero), peaks, then falls back through it (far zero). Every zero distance has a partner: with a common 5.56 load and a 2.6 in sight height, a 36 yd zero is also about a 300 yd zero, and a 50 yd zero is about a 250 yd zero. The exact partner depends on velocity, BC and sight height.

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

Enter your zero distance, sight height, muzzle velocity and G1 BC to get near and far zero, where to hit when sighting in at 25 yd, drop at each range, and MOA/MIL clicks.

A 25 yd zero is not a 100 yd zero.

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)

Sight-in At (yards)

Scope Click

Point of Impact vs. Point of Aim

Range	Velocity	POI	MOA	MIL	Clicks

MOA, MIL and clicks are the come-up to dial (U = up, D = down) to hit point of aim at that range. Approximate: G1 drag, standard sea-level atmosphere, no wind or spin drift.

Zero Equivalence for This Load

Zero at	Other crossing	POI at 100	Max rise

Scope Click Calculator — Move Your Group

Target distance (yd)

Group high (+) / low (−) (in)

Group right (+) / left (−) (in)

—

Uses the scope click value selected above. Dial the turret in the direction shown to move impact onto the point of aim.

What One Click Moves the Impact (inches)

Distance	1 MOA	¼ MOA click	1 MIL	0.1 MIL click
25 yd	0.262	0.065	0.90	0.090
50 yd	0.524	0.131	1.80	0.180
100 yd	1.047	0.262	3.60	0.360
200 yd	2.094	0.524	7.20	0.720
300 yd	3.142	0.785	10.80	1.080
500 yd	5.236	1.309	18.00	1.800

Metric: 1 MOA = 2.91 cm and 1 MIL = 10 cm at 100 m. The same 1 in correction needs four times as many clicks at 25 yd as at 100 yd.

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

Quick answer

A 25 yd zero is not a 100 yd zero. With a typical .308 load (2,700 fps, G1 BC 0.41, scope 1.5 in above bore), a 25 yd zero hits about 2.7 in high at 100 yd and is on again near 226 yd. To be zeroed at 100 yd, sight in so the group lands about 0.7 in low at 25 yd, then confirm at 100. 1 MOA is 1.047 in at 100 yd, so a ¼ MOA click moves impact 0.26 in at 100 yd but only 0.065 in at 25 yd. Values are approximate.

Examples

.308, 2,700 fps, BC 0.41, 1.5 in sight	Other zero (≈)	POI at 100 yd
25 yd zero	226 yd	+2.7 in
50 yd zero	118 yd	+0.2 in
100 yd zero	59 yd (near)	0
200 yd zero	29 yd (near)	+2.0 in

Enter your zero, sight height, velocity and BC to get near/far zero, the 25 yd sight-in point, drop, come-ups and clicks.

Summary

This rifle zero calculator estimates the point of impact (POI) relative to point of aim from 0 to 500 yards or meters. It uses sight height above bore, muzzle velocity and the G1 ballistic coefficient to model bullet drop from gravity and drag. It also shows the near and far zero (where the bullet crosses the line of sight), how high or low to hit when you sight in at 25 or 50 yd, a zero-equivalence table, the MOA and MIL come-up and scope clicks for every range, and a click calculator to move a group onto the bull. All values are approximate (standard atmosphere, no wind), so confirm on paper.

How it works

Enter your zero range — the distance you want the rifle sighted in for (for example 100 yd).
Enter the sight height above bore (about 1.5 in for most scopes, 2.6 in for an AR with a carry-handle-height optic), muzzle velocity and G1 BC.
Set the sight-in distance (25 yd by default) and your scope click value (¼ MOA or 0.1 MIL are most common).
Click Calculate to see near and far zero, where to hit at the sight-in distance, and a table of POI, MOA, MIL and clicks to 500 yd.
Use the zero-equivalence table to see what each common zero distance means for your load.
If your group is off, enter its distance and offset in the click calculator to get the direction and number of clicks to dial.

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: 2026-10-10 · Reviewed by Nham Vu