Repointing Mortar Calculator – Volume, Bags & Cost
THE HANDYMAN HUB · FREE CALCULATOR
Repointing Mortar Calculator
Estimate refill volume, optional bags or bulk purchases, patch work and separate preparation and pointing costs.
YOUR ESTIMATE
Your repointing mortar estimate
Treated joint volume, whole purchases and optional job price.
Enter joint dimensions and sections, then calculate.
Inputs changed. Calculate again to update your estimate.
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Estimate joint repair without ordering a new wall
Use repointing depth and the measured repair area or joint lengths to estimate refill mortar. Patch repairs and full-face work require different measured extents; do not assume every visible joint needs the same treatment.
The brick and block calculator is the route for new masonry units and new-build mortar. Keep replacement units as a separate item when a repair includes both replacement bricks and repointing.
For associated rainwater work, the guttering and downpipe calculator provides a separate material schedule. The rendering calculator estimates a different surface finish. A quantity result does not select a compatible repair mortar or diagnose the cause of deterioration.
MEASURE · REPAIR · ESTIMATE
Repointing mortar calculator for joint volume, bags and costs
This free repointing mortar calculator estimates the volume needed to refill masonry joints. Choose regular brick or block face measurements, or enter measured joint lengths for work that does not suit a repeating masonry pattern. Optional purchases and separate preparation and pointing labour turn the quantity into a printable job estimate.
Repointing renews a portion of the joint near the face. It is different from estimating all the mortar used to build a new wall. The actual joint width, refill depth, extent of repairs and product yield matter more than a generic allowance per wall.
How to use the calculator
- Choose metres and millimetres or feet and inches.
- Select regular masonry face area or directly measured joints.
- Enter actual face and joint dimensions, or the average measured joint width.
- Set the default refill depth and add sections with any depth overrides.
- Use the repointed percentage for patch work and add a deliberate loss reserve.
- Leave purchases at volume only, or enter a bag/tub yield or bulk order increment.
- Add optional costs, calculate and review the printable result.
Regular brick and block face estimates
Face mode uses the exposed masonry unit’s length and height, excluding the joints. It then adds the entered horizontal bed-joint width and vertical joint width to form a repeating module. The difference between the unit face and the module represents the joint area.
This method counts the intersection between a bed joint and a vertical joint once. Simply adding two full overlapping strips would overstate the volume. The calculator also estimates the treated joint length from the same repeating module, which can help when a labour rate is expressed per length of joint.
The result is still an approximation. Boundary joints, returns, unusual bonds, mixed brick sizes and irregular stonework can differ from a repeating rectangular module. For those situations, directly measured joint lengths or a representative trial area may provide a more useful basis.
Measured joint lengths for irregular work
Measured mode multiplies the treated joint length by average joint width and refill depth. For example, 100 m of joints at 10 mm wide and 20 mm deep represents 20 litres of finished mortar before losses. A 10% reserve makes that 22 litres.
The measured lengths must represent non-overlapping volumes. Avoid counting the same intersection twice, and do not assume a single average width represents very different parts of an irregular wall. Separate estimates can handle materially different joint widths or products more clearly.
Face width, face height and opening area are retained but ignored in measured-joint mode. Conversely, the measured joint-length field is ignored in face mode. Switching method does not erase your notes, but the active method determines which measurements are used.
Depth, patch percentages and repeated sections
Enter the actual average depth to refill, not wall thickness or an assumed full mortar-bed depth. Each section can override the default depth. This is useful when one area has shallow repairs and another contains deeper eroded joints.
The calculator does not prescribe how deeply to rake out a joint. Appropriate preparation depends on the masonry, existing mortar and repair specification. Depth should describe the work that has been assessed, rather than becoming an instruction to remove sound material.
Use the repointed percentage for selected patch work. A 50% entry applies half of that section’s regular joints or measured length, including copies. In face mode it also reduces the treated face area used for area-based labour. This assumes the selected joints are representative; if the damaged patches are unusually deep or wide, use separate measurements.
Openings deduct from each face before copies and patch percentage are applied. Enter a deduction per copy. Two matching walls with the same opening use the opening area once in the row and two copies, avoiding a double deduction.
Allowing for losses and uncertain cavities
The reserve percentage adds to the calculated refill volume. Use it deliberately for handling losses, mortar left on tools, irregular cavities or other assessed uncertainty. It starts at zero so the amount is visible rather than hidden inside a preset rule.
A reserve cannot correct fundamentally wrong dimensions. If the joint contains substantial voids, or the wall has mixed widths and depths, a trial section and supplier advice may be more reliable than increasing a general percentage. The calculator reports the basic volume and the volume with reserve separately.
Converting finished volume to bags or tubs
Use the manufacturer’s finished mixed yield per bag or tub. Dry bag mass is not a volume, and a 25 kg bag does not imply 25 litres of usable mortar. Different products, aggregates and water requirements can produce different yields.
The bag method divides required finished mortar by the entered yield, rounds up to whole units and subtracts usable matching whole bags or tubs already available. For a 22 litre requirement and 10 litre finished yield, three whole units are needed before stock is deducted.
The optional mass per bag reports the total new purchased product mass. It does not estimate fresh mortar density or convert wall volume directly to dry ingredients. Leave it blank if the information is not useful.
Volume-only mode is appropriate when the mortar has been specified but its purchase yield has not yet been confirmed. It does not include a material purchase cost. The calculator deliberately does not choose a cement, lime or aggregate ratio.
Bulk mortar quantities
Bulk mode deducts usable matching mortar volume and rounds the remaining requirement up to the supplier’s order increment. The price is entered per displayed volume unit: litres in metric mode or cubic feet in imperial mode. Check that the rate and order increment describe the same product and supply basis.
Only count stock that remains suitable for use under the product’s storage and handling instructions. A quantity of old or incompatible material should not reduce the new order merely because its nominal volume is known.
Raking-out and pointing labour
Preparation and pointing have separate optional labour sections. Each can use treated face area, treated joint length, hours or days. This helps when the preparation is more demanding than filling and finishing, or when access and protection dominate the job.
Area labour requires face measurement mode because measured joint lengths do not establish a wall area. In measured mode, choose joint length or time instead. Treated quantities include the patch percentage and copies, while time quantities are the whole-job hours or days you enter.
A combined contractor rate may already include both preparation and pointing. In that case, use one line or divide the rate intentionally; do not add a second labour charge for work already covered. Access, protection, delivery and other costs are separate optional entries.
Compatible mortar and a careful repair
This tool calculates quantities rather than selecting a repair specification. Mortar compatibility, masonry condition, exposure and historic fabric need consideration before choosing a product. A higher-strength mortar is not automatically a better repair.
The SPAB guidance on inappropriate cement pointing explains why unsuitable pointing can affect older masonry. Its guide to repairing old brick walls discusses assessing defects and repairs. Use appropriate advice for the building and follow the chosen mortar supplier’s instructions.
Frequently asked questions
Is this the same as mortar for building a new wall?
No. It estimates the near-face joint volume being refilled. New-wall mortar calculations involve a different volume and should use the Brick & Block Calculator.
Can I use it for irregular stonework?
Use measured, non-overlapping joint lengths with representative widths and depths. A repeating brick-face module is unlikely to describe irregular stonework reliably.
Does it tell me how deep to rake out?
No. Enter the depth from the assessed repair specification. The calculator does not instruct you to remove sound mortar or select a joint finish.
How do I allow for patch repairs?
Set the repointed percentage for each section, or measure the actual repaired joint lengths. Use separate sections when patch depths differ.
Why do I need the product’s bag yield?
Finished mortar volume cannot be inferred reliably from dry bag mass alone. The supplier’s finished yield connects the required volume to whole purchases.
Will switching a section closed remove its costs?
No. Closing labour or cost details retains active values. Choose None for a labour line, or volume-only purchasing, to exclude those costs while retaining entries.
Can I print the estimate for free?
Yes. Calculate and use Print / Save PDF. No account, email address or purchase is required. The separate quote and invoice product is optional.
Yield and application reference
Tŷ-Mawr’s quantity calculators provide supplier-specific planning resources. Check finished yield and application guidance for the exact selected mortar; the calculator’s geometry does not make different products interchangeable.
Related calculators
Need a worked example? Read our Repointing Mortar Quantities: Joint Width, Depth and Yield before ordering.