Calculate Group Size & MOA With Your iPhone

Understanding the numbers behind MOA is essential before you trust any Shortcut output. One MOA equals 1.047 inches at 100 yards, which is approximately 29.1 mm at 100 metres. At 50 yards — a common zeroing distance for UK airgun shooters — 1 MOA is roughly 0.52 inches or about 13.3 mm. When your Shortcut returns a group size, remember it is measuring the extreme spread (centre-to-centre of the two widest shots). A five-shot group under 1 MOA from a sub-12 ft-lb air rifle at 35 yards is excellent; from a centrefire bolt-action at 100 metres, it is a reasonable baseline. Context matters: always record the number of shots, conditions, and whether you are measuring from a rest or unsupported.

Budget tiers for scopes directly affect your ability to measure and repeat tight groups. Entry-level optics in the £80–£200 bracket — brands like Bushnell or lower-tier Athlon models — will get you shooting but may suffer from inconsistent turret tracking, meaning your MOA adjustments do not reliably move the point of impact by the expected amount. Mid-range glass from £250–£600, including popular Vortex Diamondback and Leupold VX-Freedom lines, tends to offer dependable tracking and clearer glass. Above £600 you enter the territory of Zeiss Conquest, Nightforce SHV, and higher Athlon Ares or Vortex Viper models, where repeatability and optical clarity support sub-MOA work at genuine long range.

A common mistake UK buyers make is conflating group size with zero accuracy. Your group might measure a beautifully tight 0.6 MOA, but if the centre of that group is 3 MOA left and 2 MOA high, you still have a problem. Use your Shortcut to measure group size as a separate exercise from zeroing. Another frequent error is measuring too few shots: a three-shot group is a minimum for a rough check, but five shots give a much more honest picture. Ten-shot groups are better still for serious load development. Also beware of measuring from the outer edge of bullet holes rather than centre-to-centre — this inflates your figure by one bullet diameter.

UK-specific context matters enormously when interpreting your MOA figures. A sub-12 ft-lb air rifle — which in England and Wales requires no licence, though Scotland mandates an Air Weapon Certificate for any air weapon — is realistically limited to humane-kill shots on rabbits, grey squirrels, corvids, and pigeons out to roughly 35–45 yards. At those distances, even a 2 MOA group may be perfectly adequate for ethical pest control. FAC-rated air rifles and centrefire rifles extend effective range considerably, but the principle remains: your group size in MOA tells you the maximum distance at which you can reliably keep shots within a kill zone. For deer stalking — roe, muntjac, or fallow — always check close seasons and ensure your group size at your intended range keeps all shots within the vital area. Consult BASC or your local police firearms licensing department for any queries on legal requirements.

Matching your measurement routine to your discipline is key. If you shoot field target or HFT with an air rifle, you need a scope with close parallax adjustment down to around 10 yards, and your groups will be measured at varying distances — the Shortcut's ability to accept different range inputs is invaluable here. If you are a range shooter punching paper at 100–300 metres, consistency of measurement method matters more than speed. For those using thermal scopes from Pulsar or Hikmicro, or night-vision clip-ons for foxing, group verification is best done in daylight with your day scope first, then confirmed at night; the Shortcut works the same way regardless. Long-range shooters working in MRAD rather than MOA can adapt the formula easily — 0.1 mil equals 1 cm at 100 metres — or simply build a second Shortcut for mil-based calculation.

The brand landscape shapes what turret language your Shortcut needs to speak. Vortex, Leupold, and Bushnell scopes are widely available in MOA turret increments (typically ¼ MOA per click) across their hunting and tactical lines, making them a natural fit for a MOA-based Shortcut. Nightforce, Athlon, and Zeiss increasingly default to MRAD in their tactical and long-range models, reflecting the metric-friendly preference of European and PRS competition shooters. Before building your Shortcut, confirm whether your scope adjusts in MOA or MRAD — mixing the two is a recipe for wasted ammunition and frustration. If you own scopes in both systems, build two Shortcuts and label them clearly. The beauty of iPhone Shortcuts is that they cost nothing and take minutes to duplicate and adapt.