Chronograph ES / SD Statistics
Mean, extreme spread, and standard deviation from a string of chronograph readings.
How this works
These are the same basic statistics any chronograph's software computes, applied here to whatever string of velocities you enter by hand: the average velocity, the spread between your fastest and slowest shots, the standard deviation (a measure of how tightly the shots cluster around the mean), and coefficient of variation (standard deviation as a percentage of the mean, useful for comparing consistency across very different velocity levels).
How many shots make a meaningful string
A 3-shot string can look great by luck and still hide real inconsistency; most serious load development uses at least 5, and often 10 or more, shots per string before drawing conclusions about a load's true consistency. A single unusually low or high shot can swing extreme spread dramatically while barely moving the standard deviation, which is part of why SD is often considered the more trustworthy number.
Frequently asked questions
How many shots should be in my chronograph string?
At least 5, and often 10 or more, for meaningful conclusions about a load's true consistency — a 3-shot string can look great by luck and still hide real inconsistency.
Should I care more about extreme spread or standard deviation?
Many precision reloaders weight standard deviation more heavily, since a single unusually high or low shot can swing extreme spread dramatically while barely moving the standard deviation.
What's a "good" SD for a hunting load?
It varies by cartridge and use case, but many reloaders consider single-digit to low-double-digit SD (in fps) a sign of a well-tuned load — compare your result against other strings of the same load rather than a universal target.
Explore the whole Calcs family here.
Not happy with our calculations or how it works? Let us know.
Have a suggestion for a calculator you don't see here? Let us know.
All HuntersCalcs tools
Rifle & Scope
Ballistic Coefficient Estimator Bullet Drop / Trajectory Calculator Barrel-Length Velocity Loss (Estimate) BC Truing from Chronograph Cost per Shot / Cost per Hunt Density Altitude Calculator Scope / Binocular Exit Pupil, FOV & Twilight Factor Maximum Point-Blank Range Mil-Dot / MOA Range Estimator MOA / Mil Calculator Muzzle / Downrange Energy & Momentum Free Recoil Energy & Velocity Sectional Density Calculator Sight-In / Zero Correction Spin Drift & Coriolis (Long-Range) Time of Flight & Moving-Game Lead Twist Rate & Bullet Stability Uphill / Downhill Shot Correction Wind Drift CalculatorMuzzleloader
Muzzleloader Ballistics Muzzleloader Powder: Volume, Shots per Pound & Cost Patched Round Ball: Weight, BC & TwistShotgun
Pellet Energy by Shot Size & Range Crossing-Bird Lead Pellet Count & Pattern Density Slug DropArchery & Crossbow
Arrow Drop, Sight Pin Gaps & Yardage Tape Arrow FOC (Front of Center) Arrow Kinetic Energy & Momentum Arrow Speed Estimator Arrow Spine — General Starting Point Total Arrow Weight & GPP Holding Weight from Let-Off Broadhead Penetration Reference: Energy vs. Momentum Crossbow Bolt Drop with Multi-Reticle Scope Draw Length Calculator Treestand / Angle-Shot Horizontal DistanceReloading
Case Capacity from Water Weight Seating Depth off the Lands (CBTO) Chronograph ES / SD Statistics Load Density / Case Fill % Powder Burn-Rate Reference Reloading Cost per Round & Break-Even Load Data Finder Rounds per Pound of PowderDraw Odds
Tag Draw Odds Estimator (Pilot)Land & Herd
Food Plot Seed, Lime & Fertilizer Mix Hunting Lease Cost per Acre / per Hunter Trail Camera Population Estimate (Jacobson Method)Meat Processing
Cost per Pound of Venison Cure & Salt Calculator Freezer Space Needed per Deer Jerky / Sausage Seasoning Scaler Taxidermy Cost Estimator Venison / Fat Blend Ratio (Pearson Square) Venison Cut Yield CalculatorNo calculators match your search.