Email Open Rate Calculator
Enter emails sent, bounces and unique opens to get the rate on delivered mail: opens ÷ (sent − bounces) × 100. Above 30% rates as excellent.
Open rate (%)
—
Email open rate
Open rate tells you what share of recipients opened your email. The math is open rate = unique opens / delivered × 100%, where delivered = sent − bounces. Say you sent 10,000, 300 bounced, and 2,200 were opened. That works out to 2,200 / 9,700 ≈ 22.7%. Benchmarks from Mailchimp and RD Station put average campaigns somewhere in the 20–30% band, and B2B usually trails B2C. What moves the needle most is the subject line, followed by the preview text and the sender name. One caveat: ever since Apple Mail Privacy Protection landed (iOS 15, 2021), Apple pre-fetches pixel-based opens, which inflates the number artificially. These days you get a clearer read on engagement from click rate, reply rate and conversion.
Applications
Running email marketing in tools like Mailchimp, RD Station, ActiveCampaign and HubSpot. Tracking how newsletters perform. Drip and onboarding campaigns, lead nurturing, slicing a list by engagement, A/B testing subject lines, and win-back flows aimed at subscribers who have gone quiet.
FAQ
Sent or delivered as the denominator? Use delivered, which is sent minus bounces. If you divide by sent, your open rate comes out too low, since an email that never arrived had no chance of being opened.
Is open rate still meaningful after Apple MPP? Less than it used to be, because Apple devices report opens that did not really happen. Compare cohorts measured under the same conditions, and lean on click and conversion rates instead.
What is a good open rate? It varies a lot by niche. Ecommerce tends to land around 15–25%, B2B SaaS around 20–30%, and transactional emails frequently clear 50%.
Related Tools
Net Assimilation Rate (Gregory Formula)
Computes the net assimilation rate of a plant by the classic Gregory formula, the core of plant growth analysis. The rate is the dry matter gain per day multiplied by the ratio between the difference of the natural logarithms of the two leaf areas and the difference of the areas themselves: NAR = [(W2 − W1) ÷ interval] × [ln(A2) − ln(A1)] ÷ (A2 − A1). The result measures net photosynthetic efficiency per unit of leaf area, with respiration already discounted — typical values for annual crops in full growth lie between 5 and 15 grams per square metre of leaf per day, and a decline along the cycle indicates canopy self-shading. Gregory's (1926) logarithmic form was adopted rather than the approximation NAR = mass gain ÷ (mean leaf area × interval), because the former is exact when leaf area grows linearly with dry mass over the interval, which is the standard assumption of classic growth analysis. Enter the initial and final dry masses, the initial and final leaf areas and the interval between the two samplings.
Crop Growth Rate (CGR)
Computes the crop growth rate, CGR = (W₂ − W₁) ÷ (Δt × A), the canopy's dry-matter gain per unit of ground area per day between two destructive samplings. Unlike relative growth rate, which measures efficiency per gram of existing plant, CGR measures the productivity of the LAND — it is what you compare across row spacings, seeding densities and fertiliser levels, because it answers how much biomass each square metre of field produces per day. Peak values in well-managed C4 crops fall around 20 to 30 g/(m²·day), and the integral of the CGR curve over the season is total biological yield. Enter the initial and final dry masses, the interval between samplings and the ground area sampled.
Constant-Rate Drying Period Time
Computes how long the constant-rate period of a tray drying run lasts, t = m_s × (X₁ − X_c) ÷ (A × N_c), that is, the mass of water to be evaporated divided by the surface evaporation rate. Moisture contents are on a dry basis, in kilograms of water per kilogram of dry solid, and N_c is the evaporation flux measured while the surface is still fully wet, in kg per square metre per hour. While this period lasts the surface behaves like an open pool and the rate does not depend on the material, only on the air; it ends at the critical moisture X_c, when internal water can no longer reach the surface as fast as it evaporates. Enter the dry solid mass, the initial and critical moisture contents, the exposed area and the constant evaporation rate.
Falling-Rate Drying Period Time
Computes the duration of the falling-rate drying period under the model where the rate drops linearly with free moisture starting at the critical moisture: t = m_s × X_c ÷ (A × N_c) × ln(X_c ÷ X₂). Moisture contents go in as free moisture on a dry basis, that is, with the equilibrium moisture already subtracted, which is why X₂ can never be zero — drying down to equilibrium would take infinite time, exactly what the logarithm says. Compared with the constant-rate period this is the expensive stretch: every kilogram of water removed costs far more time than in the previous stretch, because internal transport now sets the pace. Enter the dry solid mass, the critical moisture, the final free moisture, the exposed area and the constant rate at the critical moisture.
Email Bounce Rate Calculator
Bounces divided by messages sent times 100, with a rating: under 1 percent is excellent, past 2 percent your sender reputation starts to suffer.
Shear Rate (Injection)
Compute the shear rate of the molten plastic in a rectangular channel, γ = 6Q/(W·H²), from the flow rate (Q), the channel width (W) and height (H). It is a critical parameter of polymer processing: thermoplastic viscosity drops with shear rate (pseudoplastic behavior), and excessive rates degrade the material. It guides the design of runners and gates. Enter the flow rate, the width and the height of the channel.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.